US20110165013A1

US20110165013A1 - Antitarnish, antimicrobial copper alloys and surfaces made from such alloys

Info

Publication number: US20110165013A1
Application number: US12/943,196
Authority: US
Inventors: Carole Lynne Trybus; Richard P. Vierod; Peter William Robinson
Original assignee: GBC Metals LLC
Current assignee: GBC Metals LLC
Priority date: 2009-11-10
Filing date: 2010-11-10
Publication date: 2011-07-07
Also published as: CN102725430A; WO2011060034A1; KR20120099254A; EP2499269A1

Abstract

An antimicrobial, tarnish resistant copper alloy with a golden visual appearance comprising between about 1% and about 4% Ni, up to 3% Al, and optionally Zn and/or Mn up to a total of about 15%.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/259,837, filed on Nov. 10, 2009. The entire disclosure of the above application is incorporated herein by reference.

BACKGROUND

This invention relates to antimicrobial copper alloys, and to surfaces made from such alloys, and in particular to tarnish resistant antimicrobial copper alloys and surfaces made from such alloys.
Copper and copper alloys are known to have useful antimicrobial properties. These metals can kill human pathogens, including bacteria such as E. coli 0157, Listeria monocytogenes, Salmonella, and Methicillin-resistant Staphylococcus aureus (MRSA). The Environmental Protection Agency has declared that alloys containing 65% or more copper have inherent antimicrobial properties. See, Antimicrobial Copper Alloys Group I (EPA Reg. No. 82012-1), Antimicrobial Copper Alloys Group II (EPA Reg. No. 82012-2), Antimicrobial Copper Alloys Group III (EPA Reg. No. 82012-3), Antimicrobial Copper Alloys Group IV (EPA Reg. No. 82012-4), and Antimicrobial Copper Alloys Group V (EPA Reg. No. 82012-5), incorporated herein by reference.
Because of this antimicrobial property, copper and copper alloys would at first blush appear to be good candidates for fabricating surfaces in health care and food service facilities, and even in home and industrial settings. However copper's tendency to tarnish, which can be accelerated by the application of certain cleaners used in such environments, makes many copper alloys unsuitable for such uses. Tarnishing is psychologically and aesthetically undesirable for such surfaces, particularly in health care and food service institutions, where tarnished surfaces would appear unattractive and unclean. Furthermore, the distinctive copper color of many copper alloys limits their acceptability for some applications.
While some silver-toned tarnish-resistant antimicrobial copper alloys are known (e.g., C710), for at least some applications it is desirable to avoid silver-toned colors because these may be confused with more familiar silver-toned surfaces such as stainless steel, which while they can be sterilized, are not regarded as antimicrobial. C706 is another tarnish resistant antimicrobial copper alloy, but has a rose color, which may not be desirable for some applications.

SUMMARY

A preferred embodiment provides alloys with a combination of antimicrobial properties, attractive appearance, and tarnish resistance. Generally, the alloys of this preferred embodiment comprise at least 1% Ni, and up to 3% Al. (Percentages are weight percentages unless otherwise indicated.) In a more preferred embodiment, the alloys have a golden visual appearance, and contain Zn and/or Mn up to about 15%. Other elements that do not negatively impact tarnish resistance or antimicrobial activity of the alloy can be present.

DETAILED DESCRIPTION

Embodiments of this invention provide alloys, and surfaces made with such alloys, with a combination of antimicrobial properties, attractive appearance, and tarnish resistance. In a preferred embodiment, the alloy has an attractive golden visual appearance.
Generally the alloys of this preferred embodiment comprise between about 1 and about 4% Ni, and up to 3% Al. (Percentages are weight percentages unless otherwise indicated.) In a more preferred embodiment the alloys contain Zn and/or Mn up to about 15%. Other elements that do not negatively impact tarnish resistance or antimicrobial activity of the alloy can be present.
As detailed below, the inventors have observed that Cu—Zn alloys performed poorly both in touch and cleaning testing compared with other alloys; but that Cu—Ni alloys performed very well in both touch and cleaning testing. Resistance to tamishment by touching appears to be a more significant differentiator than other properties, such as resistance to cleaning agents and humidity.
Of the alloys that the EPA recognizes as antimicrobial, the inventors have found that alloys of Cu—Ni—Al provide a desirable combination of tarnish resistance and color, and that in particular alloys of Cu—Zn—Mn—Ni—Al, such as those identified herein as K475, K476, K589, K592, and K593 provide a desirable combination of antimicrobial activity, tarnish resistance, and a desirable golden visual appearance.

Nickel

In general, nickel is present in sufficient amounts to improve tarnish resistance. Generally, nickel in excess of about 1% improves tarnish resistance, and the nickel content is preferably at least 1.5%. In Cu—Ni—Al alloys the Ni content may be as high as 6.9% or higher. There is not necessarily an upper limit on nickel content, but nickel content is generally limited by its cost compared to the other alloying elements, and its effect, together with the other alloying elements, on the color of the alloy.

Aluminum

Aluminum improves resistance to tarnishnient from touching. Aluminum is preferably present in amounts up to about 3%. It is generally preferred that aluminum be present at a level of at least 0.6%. Additional aluminum above 3% does not appear to be necessary, and in amounts above about 8% to 11%, can negatively affect antimicrobial activity of the alloy. See, Use of Copper Cast Alloys to Control Escherichia coli 0157 Cross-Contamination During Food Processing, Applied and Environmental Microbiology, June 2006, pp. 4239-4244, incorporated herein by reference.

Zinc

Zinc, alone or in combination with manganese, improves the tarnish resistance of Ni—Cu and Ni—Al—Cu alloys, and affects their color. If zinc is present without manganese, then the zinc content is preferably at least about 6.8%, and preferably less than about 15%. If zinc and manganese are both present, zinc can be present in any amount, but it is preferable that the total content of zinc and manganese does not exceed a level which increases susceptibility to stress corrosion cracking, generally believed to be about 15%. Where both zinc and manganese are present, the zinc content is preferably between about 6.8% and about 10.8%. Considerations in setting the upper limit of the zinc content include resisting stress corrosion cracking, and maintaining desired color.

Manganese

Manganese, alone or in combination with zinc, improves the tarnish resistance of Ni—Cu and Ni—Al—Cu alloys, and affects their color. If manganese is present without zinc, then the manganese content is preferably at least about 4.8%, and preferably less than about 15%. If manganese and zinc are both present, manganese can be present in any amount, but it is preferable that the total content of zinc and manganese does not exceed a level which increases susceptibility to stress corrosion cracking, generally believed to be about 15%. Where both zinc and manganese are present, the manganese content is preferably between about 4.8% and about 6.9%. Considerations in setting the upper limit of the manganese content include resisting stress corrosion cracking, and maintaining desired color.

Total Zinc and Manganese Content

It is believed preferable to maintain the total content of Zn and Mn below a level which increases susceptibility to stress corrosion cracking, generally believed to be about 15%.
Experimental alloys (identified with prefix K) for Examples 1-5 were prepared by casting into 10 pound laboratory ingots. Alloys for Example 6 were prepared by direct chill casting into 7 inch×30 inch×25 foot bars. The production bars and laboratory ingots were both processed to mill plate by soaking at about 850° C. and hot rolling to between 0.5-0.6 inch thick. In each case, the hot rolled plate or coil was milled to remove surface oxides developed during hot rolling. The alloys were then processed to the condition in which they were tested by sequential cold rolling and annealing steps to produce the desired metallurgical condition.

Example 1

Eight commercial and four developmental alloys were subjected to cleaning, touch testing, and humidity testing.
The tested alloys (Table 1) were either as-rolled (AR) or roughened with Scotch-Brite® (SB).

TABLE 1

Alloys Used in Example 1

	Alloy ID	Composition

	C110	Cu
	C230	Cu—15Zn
	C260	Cu—25Zn
	C5248	Cu—10Sn + Fe, Ni
	C638	Cu—2.8Al—1.8Si + Co, Ni, Fe, Mn, Zn
	C706	Cu—10Ni—1.5Fe—1.0Mn—1.0Zn
	C710	Cu—10Ni—0.6Fe—0.5Mn—0.5Zn
	K444	Cu—18Mn—14Zn—1.5Al
	K445	Cu—17Mn—12Zn
	K451	Cu—10Mn—14Zn—3.75Ni
	K453	Cu—16Mn—12Zn—3Ni
	C713	Cu—25Ni—0.4Mn
	304LSS	Fe—19Cr—10Ni—0.03C (nominal composition)

	Compositions are analyzed compositions for K-alloys, and nominal compositions for all other alloys

Cleaning Testing

All the alloys were degreased with isopropyl alcohol before testing. The cleaners used, along with their respective measured pH, are given in Table 2.

TABLE 2

Cleaners used in Example 1 (with their measured pH)

		Measured
ID	Commercial Name, Ingredients if Provided	pH

PA	Pro Bowl: phosphoric acid (8%)	0
WA	Wex-All	1
HP	Proxi ®: Hydrogen Peroxide (<8%)	2
F	Fantastik (anti-microbial): measured pH 11	11
	dimethyl benzyl ammonium chlorides .11%
	dimethyl ethylbenzyl ammonium chlorides .11%
D	Dawn ® Dish Soap:diluted with water (1:10)	8
WA-d	Wex-All, diluted 1:128 water	4
P	Purell © hand Cleaner, 62% ethyl alcohol	5

All samples were wiped with a cloth saturated with the cleaner (PA, WA, HP, and D) or sprayed (in the case of F), and wiped off twice daily with a minimum of 4 hours between cleanings for ten days. (Wex-All, which is a general disinfectant, was used at full strength and not according to the manufacturer's recommendation. At this strength Wex-All appeared to leave a film on the surface which could be readily removed with a 50:50 Wex-All solution. This film darkened over a period of several hours to overnight.) All tested alloys were judged by at least three independent judges according to the following criteria:
1 No Discoloration
2 Less than 60% light discoloration
3 More than 60% light discoloration—no dark areas
4 Complete discoloration-some very dark areas
5 Majority is dark discoloration.
with lower scores being better than higher scores. The results are reported in Table 3A.
In general, the more acidic cleaners had a much stronger effect on the alloys (particularly K444, K445, K451, and K453 and C110 and C230). These alloys contain either high Mn, and/or low Zn. It appears when comparing the C230 to the C260 that more Zn may be beneficial, while higher Mn may cause the alloy to be affected more strongly by acids. Alloy 0638, with Al+Si was also significantly affected by the acid-containing cleaners.
Because C110 and C230 performed poorly in the first round of testing, they were eliminated from further testing, and the remaining eight alloys, together with standard 304LSS were tested. The tested alloys (Table 1) were either as-rolled (AR) or roughened with Scotch-Brite® (SB). All were degreased with isopropyl alcohol before testing. Diluted Wex-All (WA-d) and Purell hand cleaner (P) (see Table 2) were used. Both cleaners were wiped on 2 times daily at least 4 hours apart. The cleaners were not wiped off. All tested alloys were judged by at least three independent judges according to using a 3 point, rather than the 5 point scale identified above:
1 Unchanged
2 Light discoloration—non uniform
3 Light discoloration—uniform
with lower scores being better than higher scores. The results are given in Table 3B.
New composite cleaning scores for the alloys were determined combining the scores for some of the cleaners used in part 1 and the two additional cleaners used in part 2. These are shown in Table 3C.

Touch Testing

Touch testing consisted of having a plurality of different people touch the samples of each of the alloys (except 304LSS) for 5 minutes twice daily for 21 days. Alloys were rotated among people each week for 3 weeks. All tested alloys were judged by at least three independent judges according to the following criteria:
1 Little if any discoloration
2 Light discoloring incomplete
3 Discolored more than 75% but not deep
4 Deep discolored spots
5 Complete and deep discoloration
with lower scores being better than higher scores. The results are reported in Table 4.

Humidity Testing

Resistance to humidity was tested by placing samples of each of the alloys (except 304LSS) in a humidity chamber at 28° C. and 95% humidity for 3 weeks. All tested alloys were judged by at least three independent judges according to the following criteria:
1 Slight water marking
2 Some water marks
3 Water marks no pits
4 Some pits with water marks
5 Many pits with water marks
with lower scores being better than higher scores. The results are reported in Table 5.
The results of the three tests were compiled, and are reported in Table 6A. Of the development alloys, K451 was the best performing, with a total score of 18. K451 had the lowest Mn of the development alloys, and contained 3.75% Ni. The results using the new cleaning scores of Table 3C and the touch scores of Table 4 and humidity scores of Table 5 are reported in Table 6B.

TABLE 3A

Cleaning Test Results from Example 1, Part 1

Alloy

C110

C230

C260

C5248

C638

C706

C710

K444

K445

K451

K453

C713

Condition

Cleaners

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

PA	5	5	4	5	3	4	2	2	5	5	2	3	2	2.5	5	5	4	4	2
WA	3	4	3	3	3	2	2	2	3	3	3	3	2	2	4	4	4	4	3
HP	3	3	3.5	3	1	1	1	2	2	3	1	2	1	1	1+	1°	1	1	1
F	5	3	4	3	1	2	1	1	3	3	1	1	1	1	2	2	1	2	1
D	5	4	5	4	1	2	3	3	3	4	1	1	1	1	2	2	2	1.5	1
Cleaning	21	19	19.5	18	9	11	9	10	16	18	8	10	7	7.5	14	14	12	12.5	8
Composite
Score

*specimens darkened over a period of a few hours to overnight.
°Darkened overnight

TABLE 3B

Cleaning Test Results from Example 1, Part 2

Alloy

C260

C5248

C638

C706

C710

K444

K445

K451

K453

C713

304SS

Condition

Cleaners

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

WA-d	3	2	3	3	3	3	2	1.5	1	1	1	1	2	1.5	3	2	2	2	2	1	1	1
P	2	2	2	2	2	2	2	2	1.5	2	2	2	2	2	2	2	2	2	2	2	2	2
Total	5	4	5	5	5	5	4	3.5	2.5	3	3	3	4	3.5	5	4	4	4	4	3	3	3

AR As-rolled
SB Scotch-Brite ®

	TABLE 3C

	Alloy

260

5248

638

706

710

K444

K445

K451

K453

713

Condition

Cleaners

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

Wex-All	3	2	3	3	3	3	2	1.5	1	1	1	2	3	2	2
Dillute
Hand	2	2	2	2	2	2	2	2	1.5	2	2	2	2	2	2
cleaner
Proxi	1	1	1	2	2	3	1	2	1	1	1+	1°	1	1	1
Fantastic	1	2	1	1	3	3	1	1	1	1	2	2	1	2	1
Dawn	1	2	3	3	3	4	1	1	1	1	2	2	2	1.5	1
Cleaning	8	9	10	11	13	15	7	7.5	5.5	6	7	8	9	8.5	7
total

TABLE 4

Touch Test Results for Example 1

Alloy

110

230

260

5248

638

706

710

K444

K445

K451

K453

C713

Condition

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

Rating	3	4	4	3	3	3	3	2	4	5	2	1	1	1	3.5	3	3	3	1

TABLE 5

Humidity Test Results for Example 1

Alloy

110

230

260

5248

638

706

710

K444

K445

K451

K453

C713

Condition

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

Rating	3	3	3	3	2	3	3	3	3	3	3	3	2	1	3	3.5	3	3	1

TABLE 6A

Composite Score for Example 1

Alloy

110

230

260

5248

638

706

710

K444

K445

K451

K453

C713

Condition

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

Touch +	6	7	7	6	5	6	6	5	7	8	5	4	3	2	6.5	6.5	6	6	2
Humidity
Grand	27	26	26.5	24	14	17	15	15	23	26	13	14	10	9.5	20.5	20.5	18	18.5	10
Total

TABLE 6B

using the cleaning scores from Table 3C and
The Humidity and Touch scores from Tables 4 and 5

Alloy

C260

C5248

C638

C706

C710

K444

K445

K451

K453

C713

Condition

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

touch +	5	6	6	5	7	8	5	4	3	2	6.5	6.5	6	6	2
humidity
Total	13	15	16	16	20	23	12	11.5	8.5	8	13.5	14.5	15	14.5	9

Example 2

Two commercial and seven developmental alloys and stainless steel were subjected to cleaning, touch testing, and humidity testing. The tested alloys (Table 1) were either as-rolled (AR) or roughened with Scotch-Brite® (SB).

TABLE 7

Alloys Used in Example 2

Alloy ID	Composition

C425	Cu—9.5Zn—2Sn
C7025	Cu—3.0Ni—0.7Si—0.1Mg
K513	Cu—3.0Sn—0.025P—0.02Fe
K519	Cu—3.0Sn—10.0Zn—0.02Fe—0.01P
K515	Cu—2.0Ni—1.5Sn—0.05Fe—0.05Mn—0.4Si
K516	Cu—2.0Ni—1.5Sn—10Zn—0.05Fe—0.05Mn—0.4Si
K475	Cu—7.8Zn—5.8Mn—2.1Ni—1.3Al
K476	Cu—10.8Zn—5.8Mn—2.1Ni—0.6Al
K477	Cu—8.8Zn—6.2Mn—2.1Ni
304L	Fe—19Cr—9Ni—2Mn + C, N, etc.

Compositions are analyzed compositions for K-alloys, nominal compositions for all other alloys

Cleaning Testing

All the alloys were degreased with isopropyl alcohol before testing. The cleaners used were Wex-All, diluted 1:128 with water (WA-d), Proxi® (HP), Fantastik® (anti-microbial) (F), and Dawn® Dish Soap diluted with water (1:10) (D).
All samples were wiped with a saturated cloth and wiped off (except the diluted Wex-All and Purell®, which were not wiped off) in the morning and at the end of the day for 2 weeks. Images were recorded every day in-between cleanings. All tested alloys were judged by at least three independent judges according to the following criteria:
1 No discoloration
2 Less than 60% light discoloration
3 More than 60% light discoloration—no dark areas
4 Complete discoloration-some very dark areas
5 Majority is dark discoloration.
with lower scores being better than higher scores. The results are reported in Table 8. With the exception of C425, all copper alloys tested were adversely affected by Wex-All. Alloys C425, K516, K475, K476, and K477 all performed at or very close to stainless steel (304L) in these cleaning tests.

Touch Testing

Touch testing consisted of having a variety of people touch the samples of each of the alloys for 5 minutes twice daily for 21 days. Alloys were rotated among people each week for 3 weeks. All tested alloys were judged by at least three independent judges according to the following criteria:
1 Little if any discoloration
2 Light discoloring incomplete
3 Discolored more than 75% but not deep
4 Deep discolored spots
5 Complete and deep discoloration
with lower scores being better than higher scores. The results are reported in Table 9.

Humidity Testing

Resistance to humidity was tested by placing samples of each of the alloys in a humidity chamber at 28° C. and 95% humidity for 3 weeks. All tested alloys were judged by at least three independent judges according to the following criteria:
1 Slight water marking
2 Some water marks
3 Water marks no pits
4 Some pits with water marks
5 Many pits with water marks
with lower scores being better than higher scores. The results are reported in Table 9.
K475 performed equal to stainless steel in both the touching and humidity tests. The other two developmental alloys, K476 and K477 both are very close in performance to the stainless. These alloys appear to be relatively unaffected by humidity or human touch in this testing. The combination of Ni+Al appears to be beneficial to resistance from tarnishing from touching and humidity, at least under these testing conditions.

TABLE 8

Cleaning Test Results for Example 2

Alloy

C425

C7025

K513

K519

K515

K516

K475

K476

K477

304L

Condition

Cleaners

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

Wex All	3	2	3	2	3	3	3	3	3	3	3	3	2	3	3	3	3	3	1.5	1
Dilute
Proxi ®	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1	1
Fantastik ®	1.5	1	1.5	1	1.5	1	1	1	1	1.5	1	1	1	1	1	1	1	1	1	1
Dawn ®	2	1	2	1.5	1.5	2	1.5	1.5	2	2	1.5	1	1	1.5	1	1	1	1.5	1	1
total	7.5	5	7.5	5.5	7	7	6.5	6.5	7	7.5	6.5	6	5	6.5	6	6	6	6.5	4.5	4
composite
w/o WAD	4.5	3	4.5	3.5	4	4	3.5	3.5	4	4.5	3.5	3	3	3.5	3	3	3	3.5	3	3

TABLE 9

Humidity and Touch Testing Results for Example 2

Alloy

C425

C7025

K513

K519

K515

K516

K475

K476

K477

304L

Condition

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

AR

SB

Humidity	1	2	3	2.5	3	3	3	2	3	3	3	3	1	1	2	2	1	2	1	1
Touch	5	5	5	5	1.5	1.5	3	3	4	3	3	3	1	1	1	1	2	2	1	1
Total	6	7	8	7.5	4.5	4.5	6	5	7	6	6	6	2	2	3	3	3	4	2	2

Example 3

Several alloys were prepared (see Table 10), and their mechanical properties compared (see Table 11).

TABLE 10

Method of Preparing Alloys in Example 3

K538	Cast, Roll 90%	Anneal 520° C./1.5 h	Roll 20.5% Stress Relief at 300° C./3 h
K539	Cast, Roll 90%	Anneal 520° C./1.5 h	Roll 20.5% Stress Relief at 300° C./3 h
K540	Cast, Roll 90%	Anneal 550° C./2 h	Roll 20.5% Stress Relief at 300° C./3 h
K541	Cast, Roll 90%	Anneal 650° C./3 h	Roll 20.5% Stress Relief at 300° C./3 h
K542	Cast, Roll 90%	Anneal 520° C./1.5 h	Roll 20.5% Stress Relief at 300° C./3 h
K543	Cast, Roll 90%	Anneal 520° C./1.5 h	Roll 20.5% Stress Relief at 300° C./3 h
K475A	Cast, Roll 90%	Anneal 650° C./3 h	Roll 20.5% Stress Relief at 300° C./3 h
K476	Cast, Roll 90%	Anneal 550° C./2 h	Roll 20.5% Stress Relief at 300° C./3 h

TABLE 11

Mechanical Properties for Selected Antimicrobial Alloys

Bends

	Zn	Mn	V	Al	Ni/Al	YS (KSI)	TS (KSI)	EL (%)	GW	BW

K538	9.9	6	0	0	na	60.1	66.8	15.8	0.63	0.57
K539	9.5	7.5	0.95	1.2	0.8	71.1	78.3	14.9	0.96	0.57
K540	10.3	6.5	2.1	1.25	1.7	82.6	87.8	15.2	0.68	1.78
K541	9.8	6.3	3.1	1.2	2.6	58.4	69.6	13.6	1.34	0.89
K542	0	0	2.2	2.2	1	65.4	68.8	16.1	0.63	1.34
K543	0	0	3.2	1.15	2.8	58.4	61.4	13.3	0.86	0.89
K475A	7.5	6.2	3.1	1.7	1.8	59.4	68.9	15.6	1.78	0.91
K476	10.8	5.8	2.1	0.6	3.5	69.7	76.3	15.0	0.89	1.03

Table 12 collects the results of the testing from Examples 1 through 3. In particular, data for alloys K538-K543 and alloys K589-K602 comes from testing, in accordance with the procedures set forth in Example 2. In Table 12, alloys with clean test scores of less than 4.5 and touch test scores of 2 or less are indicated as having “good” tarnish resistance.
Color information for selected alloys is also indicated in Table 12, based upon the following comparative scale:


W++ (C713)	0	Super White
W+	0.5	Very White
W	1	White
W− or WG	1.5	White-Gold
YG	2	Yellow-Gold
G	2.5	Gold
Cu	3	Copper
Cu−	3.5	Light Copper
RG	4	Red-Gold

As disclosed in co-assigned U.S. Pat. No. 6,432,556 (incorporated herein by reference), color determination may be by spectroscopy or other objective means. Instruments, such as provided by Hunter Associates Laboratory, Inc. of Reston, Va., quantify color according to a lightness attribute commonly referred to as “value” and two chromatic attributes commonly referred to as “hue” and “chroma”. Hue is color perception, the recognition of an object as green, blue, red, yellow, etc. Chroma is color concentration and ranges from grey to pure hue. Value is the lightness of the color and ranges from white to black. One method of specifying color is by a CIELAB scale. CIE stands for Commission Internationale de l'Eclairage (International Commission on Illumination) and. LAB stands for the Hunter L,a,b scale. The CIELAB color chart expresses hue as a combination of an a* value and a b* value extending arcuately about the color chart, with +a* being red, −a* being green, +b* being yellow and −b* being blue. Chroma is expressed as a value from the center of the circle with the center (0) being grey and +/−60 being full richness of the specified color. Value is expressed as an L* number ranging from white to black, such that the combination of hue, chroma and lightness represents a specific point on a three-dimensional sphere and a specific color.

Thus, alloys K513, K475, K475A, K476, K477, K589, K592, K593, and K599 provide antimicrobial materials with good tarnish resistance. Further, alloys K475, K475A and K476 provides antimicrobial materials with good tarnish resistance and a whitish golden color, and alloy K477 provides an antimicrobial material with good tarnish resistance and a yellowish golden color.
Tables 13-15 show mechanical properties for some of the alloys in Table 12.
Table 16 is a table of other possible antimicrobial, tarnish-resistant alloys, with desirable appearance and color traits.

TABLE 12

									Cleaning
						Ni/Al			Score:	Touch	Tarnish
Alloy	Condition	Zn	Mn	Ni	Al	ratio	Sn	other	P, F, D	Score	Resistance	Color

C110	AR	0	0	0	0	0	0	0	13	3
C110	SB	0	0	0	0	0	0	0	10	4
C230	AR	15	0	0	0	0	0	0	12.5	4
C230	SB	15	0	0	0	0	0	0	10	3
C260	AR	30	0	0	0	0	0	0	3	3
C260	SB	30	0	0	0	0	0	0	5	3
C5248	AR	0	0	0	0	0	10	Fe, Ni	5	3
C5248	SB	0	0	0	0	0	10	Fe, Ni	6	2
C638	AR	0	0	0	2.8	0	0	1.8Si, Mn, Co, Ni, Fe,	8	4
								Zn
C638	SB	0	0	0	2.8	0	0	1.8Si, Mn, Co, Ni, Fe,	10	5
								Zn
C706	AR	1	1	10	0	0	0	1.5Fe	3	2	Good
C706	SB	1	1	10	0	0	0	1.5Fe	4	1	Good
C710	AR	0.5	0.5	10	0	0	0	0.6Fe	3	1	Good
C710	SB	0.5	0.5	10	0	0	0	0.6Fe	3	1	Good
K444	AR	14	18	0	1.5	0	0	0	5	3.5		W++
K445	AR	12	17	0	0	0	0	0	5	3		W++
K451	AR	14	10	3.75	0	0	0	0	4	3		W−
K453	AR	12	16	3	0	0	0	0	4.5	3		W++
C713	AR	0	0.4	25	0	0	0	0	3	1	Good	W++
C425	AR	9.5	0	0	0	0	2	Fe and P	4.5	5
C425	SB	9.5	0	0	0	0	2	Fe and P	3	5
C7025	AR	0	0.1	3	0	0	0	Mg, 0.7Si, Fe	4.5	5
C7025	SB	0	0.1	3	0	0	0	Mg, 0.7Si, Fe	3.5	5
K513	AR	0	0	0	0	0	3	P and Fe	4	1.5	Good
K513	SB	0	0	0	0	0	3	P and Fe	4	1.5	Good
K519	AR	10	0	0	0	0	3	P and Fe	3.5	3
K519	SB	10	0	0	0	0	3	P and Fe	3.5	3
K515	AR	0	0	2	0	0	1.5	Mg, 0.4Si, Fe	4	4
K515	SB	0	0	2	0	0	1.5	Mg, 0.4Si, Fe	4.5	3
K516	AR	10	0	2	0	0	1.5	Mg, 0.4Si, Fe	3.5	3
K516	SB	10	0	2	0	0	1.5	Mg, 0.4Si, Fe	3	3
K475	AR	7.8	5.8	2.1	1.3	1.62	0	0	3	1	Good	WG
K475	SB	7.8	5.8	2.1	1.3	1.62	0	0	3.5	1	Good	WG
K476	AR	10.8	5.8	2.1	0.6	3.50	0	0	3	1	Good	WG
K476	SB	10.8	5.8	2.1	0.6	3.50	0	0	3	1	Good	WG
K477	AR	8.8	6.2	2.1	0	0	0	0	3	2	Good	YG
K477	SB	8.8	6.2	2.1	0	0	0	0	3.5	2	Good	YG
SS304L	SB	0	2	9	0	0	0	Fe—19Cr + N + C	3	1	Good
SS304L	AR	0	2	9	0	0	0	Fe—19Cr + N + C	3	1	Good
K538	AR	9.9	6	0	0	0	0	0	6	2
K539	AR	9.5	7.5	0.95	1.2	0.79	0.00	0	4.5	2
K540	AR	10.3	6.5	2.1	1.25	1.68	0.00	0	5	1.5
K541	AR	9.8	6.3	3.1	1.2	2.58	0.00	0	4.5	1.5
K542	AR	0	0	2.2	2.2	1.00	0.00	0	5.5	3
K543	AR	0	0	3.2	1.15	2.78	0.00	0	5.5	1
K589	AR	8.2	6.1	3.05	0.9	3.39	0.00	0	4	1.2	Good
K590	AR	10.2	5	3.1	1.4	2.21	0.00	0	4.5	1.2
K591	AR	10	5.1	2.5	0.95	2.63	0.00	0	5	1.2
K592	AR	10.3	5	1.5	1.15	1.30	0.00	0	4	1.5	Good
K593	AR	6.8	5.1	3.1	1.4	2.21	0.00	0	3.5	1.5	Good

K594

AR

25.4

0

3

1.2

2.50

0.00

0

Broke on rolling

K595	AR	0	0	2.95	0.9	3.28	0.00	0	4.5	3
K596	AR	0	0	1.45	0.7	2.07	0.00	0	6	3
K597	AR	0	0	2	1.3	1.54	0.00	0	5.5	3
K598	AR	0	0	2.95	1.9	1.55	0.00	0	4.5	2
K599	AR	0	0	3.07	1.62	1.90	0.00	0	4	1.5	Good
K600	AR	0	0	2	1.6	1.25	0.00	0	4	2
K475A	AR	7.5	6.2	3.1	1.7	1.24	0.00	0	3	1	Good	WG
K602	AR	0	0	2	7.7	0.26	0.00	0	5	1

Compositions are analyzed compositions for K-alloys, nominal compositions for all other alloys

TABLE 13

Mechanical Properties
Cold Rolled to 90% + Annealed at 520° C. 75 m
Properties @.050 Gauge

				%
Gauge	TS	YS	Elong	IACS	Zn	Mn	Ni	Al

K475A	0.0506	85.5	74.6	19.9	6.3	7.5	6.2	3.1	1.7
K476	0.0498	68.8	51.7	28.9	6.4	10.8	5.8	2.1	0.6
K538	0.0488	53.7	26	36.1	6.8	9.9	6	0	0
K539	0.0506	63.1	34.3	35.2	5.3	9.5	7.5	0.95	1.2
K540	0.0502	74.1	54.8	27.6	6	10.3	6.5	2.1	1.25
K541	0.0501	79.8	65.4	23.1	6.2	9.8	6.3	3.1	1.2
K542	0.0477	54.3	33.8	32.7	21.6	0	0	2.2	2.2
K543	0.0484	48.2	28.4	31.6	24.2	0	0	3.2	1.15

TABLE 14

Mechanical Properties
Cold Rolled to 90% + Annealed at 520° C. 75 m +
Coled Rolled 30% + Stress Relief at 250° C. 120 minutes
Properties @.035 Gauge

90 deg Bends

	Gauge	TS	YS	Elong	GW	BW

K475A	0.0344	116.1	112.2	2	1.8	7.3
K476	0.0347	97.8	95.7	5.9	0.8	1.8
K538	0.0346	75.8	73.6	7.8	0.7	1.4
K539	0.0346	92.1	89.9	6.6	0.8	1.4
K540	0.0347	106.1	103.2	3.3	1.4	1.8
K541	0.0291	117.3	113.8	0.7	2.7	8.6
K542	0.0295	79.7	78	4.2	0.7	1.2
K543	0.0346	66	65	5.2	0.8	1.8

TABLE 15

Mechanical Properties
Cold Rolled to 90% + Annealed at 520° C. 75 m +
Cold Rolled 30% + Stress Relief at 470° C. 60 minutes
Properties @.035 Gauge

90 deg Bends

	Gauge	TS	YS	Elong	GW	BW

	K541	0.0290	80.2	61.5	23.8	0.0	0.0

Example 4

Alloys in Table 16, plus additional alloys were subjected to touch and cleaning tests (reported in Table 17). The sample preparation differed somewhat for these tests. The results in Table 17 were performed on samples which were polished smooth and degreased prior to testing, to remove surface imperfections in order to minimize test variables. Touch testing was done as before using a variety of people touching the samples of each of the alloys for 5 minutes twice daily for 21 days. Alloys were rotated among people each week for 3 weeks. All tested alloys were judged by at least three independent judges according to the following criteria:
1 Little if any discoloration
2 Light discoloring incomplete
3 Discolored more than 75% but not deep
4 Deep discolored spots
5 Complete and deep discoloration
with lower scores being better than higher scores. The results are reported in Table 17.
Samples of the same alloys were subjected to cleaning testing; again these samples were polished smooth and degreased. The cleaners used were, CleanCide Wipes (CleanCide), Proxi®, Fantastik® (anti-microbial), and Dawn® Dish Soap diluted with water (1:10)). All samples were wiped with a saturated cloth and wiped off, except the in case of CleanCide wipes which were wiped on without being wiped off, twice daily in the morning and at the end of the day for 2 weeks. All tested alloys were judged by at least three independent judges according to the following criteria:
1 No discoloration
2 Less than 60% light discoloration
3 More than 60% light discoloration—no dark areas
4 Complete discoloration-some very dark areas
5 Majority is dark discoloration.
with lower scores being better than higher scores. Commercial alloy C752 was included as a standard. The alloy did very well through the testing.
None of the experimental alloys K603-K637 performed well with CleanCide, but they generally performed well in the other cleaners and the touch tests. There are some slight differences within this group, such as alloys with lower Mn did slightly better than those with higher levels, e.g., K610 versus K604.

TABLE 16*

Additional Antimicrobial, Tarnish Resistant Alloys

Composition, weight %

	Ingot	Zn	Mn	Ni	Al

K603	7.4	4.9	2.1	1.3
K604	7.5	5.0	2.0	2.0
K605	7.7	5.2	3.0	1.1
K606	7.7	5.1	3.1	2.0
K607	7.4	6.0	2.1	1.15
K608	7.4	6.2	2.1	2.0
K609	7.5	5.9	3.0	1.15
K610	7.5	6.9	3.0	2.0
K611	8.5	5.3	1.9	1.2
K612	8.5	5.0	1.9	2.1
K613	8.6	5.1	3.1	0.90
K614	8.5	5.0	3.1	2.0
K615	8.4	6.0	2.1	1.2
K616	8.3	6.2	2.1	1.9
K617	8.7	5.9	3.1	1.2
K618	8.9	6.3	3.0	2.0
K619	—	—	6.4	3.0
K620	—	—	3.4	1.9
K621	—	—	2.1	3.0
K622	7.5	5.9	3.0	2.0

*Alloys with the same numbers have the same compositions, but there are slight variations in the reported compositions due to improvements in measuring techniques.

TABLE 17

Touch and Cleaning Test Results from Example 4

	Zn	Mn	Ni	Al	Touch #2	CleanCide	Proxi ®	Fantastik ®	Dawn ®

K603	7.4	4.9	2.1	1.3	1	2	1	1	1
K604	7.5	5	2	2	1	2	1	1	1
K605	7.7	5.2	3	1.1	1	2	1	1	1
K606	7.7	5.1	3.1	2	1	2	1.5	1	1
K607	7.4	6	2.1	1.15	1	2.5	1	1	1
K608	7.4	6.2	2.1	2	1	3	1.5	1.5	1
K609	7.5	5.9	3	1.15	1.5	2.5	2	1.5	1
K610	7.5	6.9	3	2	1	3	1.5	1.5	1.5
K611	8.5	5.3	1.9	1.2	1	3	1	1t	1
K612	8.5	5	1.9	2.1	1	2.5	1	1	1
K613	8.6	5.1	3.1	0.9	2	2.5	1	1	1
K614	8.5	5	3.1	2	2	2	1.5	1	1
K615	8.4	6	2.1	1.2	2*	2	1.5	1	1
K616	8.3	6.2	2.1	1.9	1*	2	1	1	1
K617	8.7	5.9	3.1	1.2	1*	2	1	1	1
K618	8.9	6.3	3	2	1*	2	2	1	1
K619	0	0	6.4	3	2	2	2	1	1
K620	0	0	3.4	1.9	1	2	2	1	1
K621	0	0	2.1	3	2	2.5	2	1	1
K622	7.5	5.9	3	2	1	2	1.5	1	1
K636	7.58	6.08	2.43	1.32	1	2	1.5	1	1
K637	8.08	5.46	2.75	1.73	1	2	1.5	1	1

C752	Cu—18N I-17-Zn	1	2	1	1	1
K513	Cu—3.0 Sn—0.025P0.02Fe	1.5	2	1	1	3
K633	Cu—2.9 Sn	4	3	1	1	2
K635	Cu—3.3 Sn—0.018P—0.01 Fe	4	2	1	1	3

nm: not measured
*these samples were only degreased and not polished smooth

Example 5

An alloy with composition of about Cu-7.75 Zn-5.75 Mn-2.5 Ni-1.5 Al would give good cleaning and touch results based upon the results of Example 4. A new series of alloys were cast, hot rolled HR75% (reduction in thickness), milled and cold rolled CR 92%, annealed under different conditions and given a small 10-14% final reduction. The compositions and mechanical test results are reported in Table 18. Alloys in Table 18 were cleaned and evaluated as in Example 4. All alloys scored 1 when cleaned with Proxi®, Dawn® diluted with water (1:10), and antimicrobial Fantastik. As before, the alloys did poorly when cleaned with CleanCide wipes, rating 3-4.

TABLE 18

Mechanical testing results from Example 5

	CR (92%) 0.035ga	CR (92%) 0.035ga
	750 C./15 s	780 C./10 s

Alloy

Chemistry

as-annealed

+14% CR

as-annealed

+14% CR

No

Zn

Mn

Ni

Al

TS

YS

EL

TS

YS

EL

TS

YS

EL

TS

YS

EL

K676	7.77	5.60	2.26	1.23	64	35	37	74	69	10	61	30	36	73	67	11
K677	7.72	5.72	2.75	1.21	66	38	31	73	65	15	63	31	38	77	70	11
K678	7.85	5.75	2.26	1.7	64	32	33	75	68	16	63	30	32	76	69	15
K679	7.7	5.67	2.72	1.7	75	53	27	77	69	14	65	32	32	77	63	14
K680	7.82	6.24	2.26	1.22	65	33	34	73	66	14	62	29	36	74	67	18
K681	7.71	6.29	2.73	1.24	65	33	34	76	70	15	64	31	36	77	71	14
K682	7.75	6.25	2.24	1.74	64	29	39	76	68	17	64	30	38	78	70	16
K683	7.71	6.25	2.74	1.75	74	49	29	78	70	14	66	32	36	78	68	14
K684	8.32	5.71	2.25	1.2	65	36	34	72	64	15	62	31	35	76	68	12
K685	8.1	5.49	2.76	1.24	65	35	35	72	64	16	64	35	35	78	68	12
K687	8.1	5.49	2.76	1.75	78	60	25	79	73	12	66	34	35	79	72	14
K688	7.64	6.02	2.26	1.25	64	33	34	72	67	15	63	32	35	76	70	12
K689	8.02	5.88	2.75	1.22	65	35	34	73	66	14	64	32	35	78	74	9
K690	8.23	6.02	2.28	1.74	65	33	35	77	70	16	65	31	35	78	70	12
K691	8.04	5.94	2.75	1.72	66	33	34	79	72	13	65	32	38	81	74	14
K692	7.86	5.24	2.5	1.45	65	35	34	73	65	16	63	31	37	75	69	12
K693	7.68	5.14	2.27	1.23	66	42	34	70	63	15	61	29	39	73	68	13
K694	7.58	5.96	2.75	1.22	65	36	34	73	67	15	64	34	37	77	72	13
K695	8.09	5.49	2.28	1.22	63	33	36	72	66	14	60	27	36	72	66	13
K696	7.63	5.45	2.25	1.75	65	33	36	74	64	14	63	31	37	77	70	17

Example 6

An alloy was cast at a production level of the composition, Cu-7.75 Zn-5.38 Mn-2.51 Ni-1.61 Al. The overall process used was:
HRP 93% 850° C.→CR 90-94%→SA 750° C.→CR 10-12%
Four items were made, one as-annealed the other 3 were one quarter hard (H01); i.e. cold rolled CR10-12% s. The plant trial results are given in Table 19.

TABLE 19

Average mechanical properties of plant trial material

Bends

				MBR/t	MBR/t
ga (in)	YS KSI)	TS (KSI)	% EL	GW	BW

Item 1 (H01)	0.0307	65.5	74.4	19.5	0.1	0.0
Item 2 (H01)	0.0390	65.3	74.1	19.3	0.1	0.0
Item 3 (H01)	0.0472	67.3	75.8	19.1	0.2	0.0
Item 4 (soft)	0.0472	31.6	64.7	36.0	0.0	0.0

Stress Corrosion Cracking (SCC) Testing

Due to the envisioned service conditions for this alloy, stress corrosion susceptibility testing was initiated in Mattsson's solution, in accordance with ASTM G37-98. Mattsson's solution is composed of copper sulfate pentahydrate, ammonium sulfate, and ammonium hydroxide in water. The pH is controlled from 7.1 to 7.5, the region of highest SCC susceptibility. Test specimens are examined periodically for cracks under a stereo microscope at 30×. A visible penetrating crack is judged a failure. In addition, the samples are evaluated for stress relaxation. If the remaining stress on the sample falls below 80% of the original stress level, the sample has failed. The recommended test duration in ASTM G37-98 is 1000 hours. It is customary to consider that survival of at least 1000 hours in this test indicates that the material is essentially immune to SCC. Samples of Item 1 (Table 19) as-received and with a relief anneal of 300° C./1 h have been tested in Mattsson's solution. All three samples of Item 1 in the as-received condition completed the test without failure as did 2 of the 3 samples of Item 1 which were relief annealed. One sample of Item 1 with the relief anneal, failed at 648 hours. The cause of the failure is not known. The plant trial material is not susceptible to SCC in Mattsson's solution.

Color Analysis

All of the alloys plus the plant trial material was evaluated for color using, a standard condition; 10 degree observer using average daylight D65. The color measurement method is accordance with paragraph 35 in this document and is as described in U.S. Pat. No. 6,432,556, incorporated by reference herein Table 20 presents the results on the alloys from Tables 18 and 19. The terms in the table are L* is light to dark, C* is aroma, h* is hue, a* and b* are the locations on the plane in space defined by L*, C* and h*. These terms are further explained in http://www.hunterlab.com/manuals/appendixa2_—5.pdf incorporated herein by reference. The dEcmc(1:c=2.0) is calculated from the color measurements and is used to compare color measurements. All alloys in Table 20 are compared to plant trial material. Note that there are no dEcmc(1:c=2.0)values over 1.1 therefore, all these alloys appear to have the same color to the human eye.

TABLE 20

Color measurements using CIELAB scale. dEcmc (1:c = 2.0) is
used to compare color measurements. See text for explanation.

CIE

D65/10

Sample ID	L*	a*	b*	C*	h*	dEcmc (I:c = 2.0)

Plant trial	86.90	1.74	14.04	14.15	82.95	0
Material
K696	87.29	1.55	14.02	14.11	83.71	0.28
K694	86.66	1.94	12.68	12.82	81.31	1.07
K689	86.86	1.78	12.60	12.73	81.98	1.06
K685	87.05	1.81	13.79	13.91	82.50	0.23
K683	86.40	1.41	13.57	13.65	84.08	0.53
K687	87.37	1.32	13.41	13.47	84.37	0.67
K684	87.29	1.76	13.26	13.37	82.45	0.59
K676	86.22	2.25	14.07	14.25	80.91	0.69
K679	87.03	1.46	13.24	13.32	83.70	0.64
K690	87.00	1.33	13.69	13.75	84.46	0.55
K680	86.56	1.90	13.21	13.34	81.83	0.68
K681	86.75	1.79	12.66	12.78	81.95	1.02
K693	87.06	2.15	13.57	13.74	81.01	0.67
K678	86.94	1.47	14.45	14.52	84.18	0.48
K695	86.51	2.02	13.84	13.99	81.69	0.44
K692	87.39	1.68	13.87	13.97	83.10	0.22
K682	86.84	1.39	13.56	13.63	84.16	0.53
K677	86.94	1.92	13.40	13.53	81.86	0.55
K688	86.75	1.99	13.26	13.40	81.47	0.70
K691	86.91	1.30	13.05	13.11	84.30	0.85

Antimicrobial Testing

Samples of Item 2 in Table 19 were tested for resistance to microbial growth. The test methodology used was based on ASTM 1153-03, “Standard Method for Efficacy of Sanitizers Recommended for the Inanimate non-Food Contact Surfaces”. The materials were cleaned and degreased and inoculated with methicillin resistant staphylococcus aureus, (MRSA). Growth was monitored on the copper alloy and a stainless steel control for 1, 2 and 4 hours at 21° C. Triplicate samples were used in the study. The stainless steel control colonized additional bacteria as time progressed, no bacteria were found on any of the copper specimens at 1, 2 or 4 hours. The inoculation and counting methods used were in accord with ASTM 1153-03. The copper alloy of Item 2 was demonstrated antimicrobial under the test conditions. Table 21 shows the percent reduction of MRSA over time on Item 2 (Table 19).

TABLE 21

Reduction in MRSA on Item 2 (Table 19) over time

Test Organism	Exposure Time	Carrier #	Percent Reduction

Methicillin	1 hour	1	>99.9999%
Resistant		2
Staphylococcus		3
aureus- MRSA	2 hours	1	>99.9999%
(ATCC 33592)		2
		3
	4 hours	1	>99.9999%
		2
		3

Nickel Release

Nickel can cause some people to have an adverse reaction. It is a desirable, but not necessary property that the alloy has low Ni release. Various methods of determining whether an alloy would release enough nickel to cause reactions in individuals with sensitivity to nickel are known. One such test consists of mixing solutions of dimethylglyoxime and ammonium hydroxide on the surface of the test article. If nickel is released, a light pink to red color results on the test article. Additional information about such testing is disclosed in http://corrosion-doctors.org/Allergies/nickelallergy.htm, incorporated herein by reference; and in Screening Tests For Nickel Release From Alloys And Coatings In. Items That Come Into Direct And Prolonged Contact With The Skin, PD CR 12471:2002 by British Standards Institution on ERC Specs and Standards.

Claims

1. An antimicrobial, tarnish resistant copper alloy comprising at least about 1% Ni and up to 3% Al.

2. The antimicrobial, tarnish resistant copper alloy according to claim 1 wherein the Ni content is at least about 1.5%.

3. The antimicrobial, tarnish resistant copper alloy according to claim 1 wherein the Ni content is between about 1.5% and about 6.5%.

4. The antimicrobial, tarnish resistant copper alloy according to claim 1 wherein the Ni content is at least about 2.9% and the Al content is at least about 1.8%.

5. The antimicrobial, tarnish resistant copper alloy according to claim 1 wherein the alloy has a golden visual appearance, and further comprises at least one of Zn and Mn in amounts such that Zn+Mn<15%.

6. The antimicrobial, tarnish resistant copper alloy according to claim 5 wherein the Mn content is 0.

7. The antimicrobial, tarnish resistant copper alloy according to claim 5 wherein the Zn content is 0.

8. The antimicrobial, tarnish resistant copper alloy according to claim 5 wherein the Zn content is between about 6% and about 12%, and the Mn content is between about 4% and about 7%.

9. The antimicrobial, tarnish resistant copper alloy according to claim 8 wherein the Zn content is between about 6.8% and about 10.8%, and the Mn content is between about 4.8% and about 6.9%.

10. The antimicrobial, tarnish resistant copper alloy according to claim 1 wherein the Ni content is between about 1.5% and about 3.1%, and the Al content is between about 0.5% and about 1.5%.

11. The antimicrobial, tarnish resistant copper alloy according to claim 10 wherein the Zn content is between about 7.5% and about 10.5%, and the Mn content is between about 5% and about 6.5%.

12. An antimicrobial, tarnish resistant copper alloy with a golden visual appearance comprising between about 1.5% and about 6.5% Ni, between about 0.6% and about 3.2% Al, and at least one of Zn and Mn in amounts such that Zn+Mn<15%.

13. The antimicrobial, tarnish resistant copper alloy with a golden visual appearance of claim 12 comprising both Zn and Mn.

14. The antimicrobial, tarnish resistant copper alloy with a golden visual appearance of claim 13, further comprising between about 6.8% and about 10.8% Zn and between about 4.8% and about 6.9% Mn.

15. An antimicrobial, tarnish resistant copper alloy with a golden visual appearance comprising between about 7.8% and about 10.8% Zn, between about 5% and about 6.5% Mn, between about 2.1% and about 3.1% Ni, and up to about 1.4% Al.

16. An antimicrobial, tarnish resistant copper alloy with a golden visual appearance comprising between about 2% and about 3% Ni, between about 1% and about 2% Al, between about 7.5% and about 8.5% Zn, and between about 5% and about 6% Mn.