HPA - 4 - Nickel-Based Superalloys
HPA - 4 - Nickel-Based Superalloys
HPA - 4 - Nickel-Based Superalloys
(a)
(b)
(a) Dendritic structure of multiphase Ni21.9Al8.1Cr4.2Ta0.9Mo
0.3Zr (at.%) intermetallic alloy, (b) SEM micrograph showing
coexisting regions in after directional solidification at V = 2.78 10 5
ms1, D dendrite, I interdendritic region, P Cr-based particles.
Properties
o Resistance to high temperature oxidation, nitridation
and carburization ;
o Fatigue resistance superior to that of nickel based
superalloys ;
o High yield strength in a large temperature range
o Good tensile and compressive yield strength at 650
1100 C ;
o Inferior mechanical properties comparing to those of
recent single crystalline nickel based superalloys.
Industrial applications
Transfer rolls
Heat treating trays
Centrifugally cast tubes
Rails for walking beam furnaces
Die blocks
Nuts and bolts
Corrosion resistance tool bits
Single crystal turbine blades
Microstructure of a
creep-resistant NiAl3Ti-0.5Hf singlecrystal alloy.
Nimonics
Key component of the microstructure is
precipitates of (Ni,Fe)3Al: `.
A modern superalloy might be 60 - 85% `
- nickel is effectively a glue holding the `
together.
Alloy Additions
Ti: goes into ` - Ni3(Al, Ti) solid soln
strengthening of `
Cr: goes into Ni matrix,
solid soln strengthening, corrosion resistance
Co: goes into both Ni and ` oxidation and
corrosion resistance lowers solubility of Al in
Ni, so enhances ` formation, improves g` high
T stability
C: combines with Cr, gives precipitates in Ni
Typical Ni-based
Superalloys
Nimonic 115:
Nimonic 80A
SRR99:
Ni, 8.5% Cr, 5% Co, 2.2% Ti, 5.5% Al, 9.5%
W, 2.8% Ta.
- Rolls Royce single crystal alloy
CMSX-4:
Ni, 6.5% Cr, 9% Co, 1% Ti, 5.6% Al, 0.6% Mo,
6% W, 6.5% Ta, 3% Re, 0.1% Hf
- advanced single crystal alloy
Comparison of
creep response in
air versus helium.
Top: 820oC. Bottom:
920oC.
Nickel
BRIGHTRAY Alloys ,
INCOLOY Alloys ,
MONEL Alloys ,
NILO/NILOMAG Alloys
,
NIMONIC Alloys ,
Nickel/DURANICKEL
Alloys ,
UDIMET/UDIMAR
Alloys