Background technology
At present, at power, petrochemical industry, transportation, particularly industrial circle such as aviation and space flight, be applied in structural metallic materials more than 600 ℃ and be generally Ni-based, iron-based and cobalt base superalloy.These materials have higher density (generally at 8.0g/cm
3More than), made member and weight of equipment are big, in order to alleviate structural weight, raise the efficiency, and reduce energy consumption, must develop the strong novel high-temperature alloy of low density, height ratio to adapt to the needs of related industries field future development.More urgent is is the superalloy of representative owing to be subjected to the restriction of fusing point with Ni base, Co base at present, near the ultimate temperature of its use.Even added three generations's superalloy monocrystalline of a large amount of precious metals, its use temperature also is no more than 1100 ℃.For satisfying the demand of gas turbine engine of new generation, being badly in need of exploitation, to hold warm ability be 1150 ℃ high-temperature structural material.
The fusing point of B2 structure long-range order NiAl is up to 1638 ℃, and is higher 300~350 ℃ than nickel base superalloy, and use temperature is expected to reach 1250 ℃; Its density 5.86g/cm
3Be 2/3 of nickel base superalloy only, the density after the alloying is 6.0g/cm
3About, thereby can improve specific tenacity effectively, reduce workpiece weight; The thermal conductivity of NiAl is big, and for general nickel base superalloy 4~8 times can make the thermograde of hot-end component reduce, thereby reduce thermal stresses, improve cold and hot fatigue property; In addition, NiAl also has excellent antioxidant property.But the normal temperature plasticity of NiAl is less than 1%, and fracture toughness property is
1000 ℃ of yield strengths of high temperature are less than 100MPa, serious restriction the utilization of its practicability.
The in-situ authigenic composite technology is one of effective way that solves material room temperature fragility and hot strength problem.By adding transition element, as Cr, Mo, V, W etc., can form pseudo-two component eutectic with NiAl is to utilize its endogenous refractory metal can make that mutually intensity improves, fracture toughness property increases.The synusia shape of eutectic structure is organized very tiny, and interlamellar spacing has only a few tenths of extremely several micron apart, and the mean free path of dislocation is very little, and the pinning between phase and phase causes the Hall-Petch type to be strengthened; In addition, the plasticity in the eutectic alloy and the NiAl fragility crackle in mutually can produce interaction, shows as the crackle bridge joint intuitively, and crack deflection and crack blunting make the toughness of NiAl pseudoeutectic alloy be improved.Fracture toughness property as NiAl-Cr (Mo) eutectic is
Its shock resistance also is better than AFN-12.But, the hot strength of NiAl-Cr (Mo) biphase eutectic crystal intermetallic compound is improved little, still can't satisfy the service requirements of gas turbine engine of new generation under 1150 ℃ of environment, carrying out further composition design and tissue design, is the effective way that improves NiAl intermetallic compound over-all properties.
Summary of the invention
NiAl-Cr (Mo) biphase eutectic crystal intermetallic compound that the purpose of this invention is to provide a kind of Ta modification, near the composition range the eutectic point of NiAl-Cr (Mo) biphase eutectic crystal alloy, reduction Al constituent content, interpolation Ta element carry out modification; And Ta element and Cr formation Laves (Cr
2Ta) phase is introduced suitable Laves mutually on the basis of the NiAl-Cr of rich Ni (Mo) two-phase structure preferably in temperature-room type plasticity and toughness, further improves the hot strength and the temperature-room type plasticity of eutectic alloy.Develop 1150 ℃ of structural intermetallic compoundses of high temperature of novel low density, high specific strength with this, alleviate structural weight, raise the efficiency, reduce energy consumption, need reach the requirement of holding 1150 ℃ of warm abilities with alloy thereby bring huge social and economic benefit and satisfy gas turbine engine of new generation.
The present invention is a kind of NiAl-Cr (Mo) biphase eutectic crystal intermetallic compound of Ta modification, form by the nickel (Ni) of purity 99.999%, the aluminium (Al) of purity 99.999%, the chromium (Cr) of purity 99.999%, the molybdenum (Mo) of purity 99.999% and the tantalum (Ta) of purity 99.999%, composition range is the Ni of 33at%, the Cr of 30at%, the Mo of 4at%, the Ta of 1~13at% and the Al of surplus.
The NiAl-Cr of described Ta modification (Mo) biphase eutectic crystal intermetallic compound can be 33Ni-30Al-30Cr-4Mo-3Ta or 33Ni-28Al-30Cr-4Mo-5Ta or 33Ni-25Al-30Cr-4Mo-8Ta or 33Ni-23Al-30Cr-4Mo-10Ta.
The advantage of the NiAl-Cr of Ta modification of the present invention (Mo) biphase eutectic crystal intermetallic compound is:
(1) suitably reduce the Al constituent content, add the Ta element NiAl-Cr (Mo) biphase eutectic crystal alloy carried out modification, and Ta element and Cr formation Laves (Cr
2Ta) phase, introduce suitable Laves mutually on the basis of the NiAl-Cr of rich Ni (Mo) two-phase structure preferably in temperature-room type plasticity and toughness, further improve the hot strength of eutectic alloy, be formed on the novel texture intermetallic compound that room temperature and high temperature all have better over-all properties with this.
(2) density of the NiAl-Cr of Ta modification (Mo) biphase eutectic crystal intermetallic compound is 6.1~6.9g/cm
3
(3) NiAl-Cr of Ta modification (Mo) biphase eutectic crystal intermetallic compound yield strength in the time of 25 ℃ is 1300~2100MPa, improve 40%~140% than unmodified NiAl-Cr (Mo) alloy, than waiting atomic ratio NiAl intermetallic compound to improve 110%~220%; Yield strength in the time of 1150 ℃ reaches 120~400MPa.
(4) compression plasticity of the NiAl-Cr of Ta modification (Mo) biphase eutectic crystal intermetallic compound improves 13% greater than 15% than unmodified NiAl-Cr (Mo) eutectic alloy, than waiting atomic ratio NiAl intermetallic compound to improve 110%.
Embodiment
The present invention is described in further detail below in conjunction with drawings and Examples.
The present invention is a kind of NiAl-Cr (Mo) biphase eutectic crystal intermetallic compound of Ta modification, be room temperature fragility and hot strength problem at the NiAl intermetallic compound, on the basis of the two-way eutectic alloy of NiAl, develop the strong biphase eutectic crystal base alloy of the element modified new type high temperature height ratio of a kind of Ta, this alloy can substitute the conventional high-temperature alloy, alleviate structural weight, cut down the consumption of energy and bring huge social and economic benefit, and further satisfy gas turbine engine of new generation and need reach the requirement of holding 1150 ℃ of warm abilities with alloy.
The NiAl-Cr of Ta modification of the present invention (Mo) biphase eutectic crystal intermetallic compound, desired raw material is made up of the nickel (Ni) of purity 99.999%, the aluminium (Al) of purity 99.999%, the chromium (Cr) of purity 99.999%, the molybdenum (Mo) of purity 99.999% and the tantalum (Ta) of purity 99.999%, composition range is: the Ni of 33at%, the Cr of 30at%, the Mo of 4at%, the Ta of 1~13at% and the Al of surplus.
33Ni-20~32Al-30Cr-4Mo-1 of the present invention~13Ta intermetallic compound adopts the preparation of vacuum arc melting method, and this method is that the raw material that takes by weighing is in proportion put into non-consumable arc furnace melting ingot casting, vacuum tightness 1 * 10
-3~5 * 10
-3Pa, 2500 ℃~3000 ℃ of smelting temperatures turn refining 3~6 times, and the raw material melting evenly gets final product.In its preparation process, usually control alloy at room temperature and mechanical behavior under high temperature by content that changes Aluminum in Alloy (Al) element and tantalum (Ta) unit that adds corresponding content simultaneously.
The intermetallic compound ingot that makes is carried out mechanics property analysis:
(1) adopt wire cutting method to cut sample and carry out proximate analysis, by the quality and the volume of accurate measure sample, the density of calculating intermetallic compound is 6.1~6.9g/cm
3, sample is diameter 6mm, the right cylinder of length 9mm.
The test of mechanical behavior under high temperature when (two) adopting material mechanics experiment machine (MTS) to carry out 25 ℃:
Yield strength is 1300~2100MPa in the time of 25 ℃, improves 40%~140% than unmodified NiAl-Cr (Mo) biphase eutectic crystal alloy, than waiting atomic ratio NiAl alloy to improve 110%~220%; Compression plasticity improves 13% greater than 15% than unmodified NiAl-Cr (Mo) biphase eutectic crystal alloy, than waiting atomic ratio NiAl intermetallic compound to improve 110%.
Adopt Instrons equipment to carry out the test of 1150 ℃ of mechanical properties of high temperature, laboratory sample is diameter 6mm, the right cylinder of length 9mm; Its yield strength is 120~400MPa.
(3) adopt material mechanics experiment machine (MTS) to carry out the test of room temperature (18 ℃) material fracture toughness, laboratory sample is the square body of 6mm * 6mm * 30mm, and the strain rate during test is 0.02mm/min, and the fracture toughness property value is 3~10MPam
1/2
Intermetallic compound of the present invention is by suitably reducing the Al constituent content near the composition range its eutectic point and adding the Ta element NiAl-Cr (Mo) two-phase alloys has been carried out modification, by Ta element and NiAl intensive Laves (Cr
2Ta) form trend mutually, introduce the hot strength that suitable Laves comes further to improve eutectic alloy mutually on the basis of the NiAl-Cr of rich Ni (Mo) two-phase structure preferably in temperature-room type plasticity and toughness, be formed on the novel texture intermetallic compound that room temperature and high temperature all have better over-all properties with this.
The present invention develops a kind of novel low density, the intermetallic compound of high specific strength, can alleviate structural weight, raise the efficiency, reduce energy consumption, need reach the requirement of holding 1150 ℃ of warm abilities with alloy thereby bring huge social and economic benefit and satisfy gas turbine engine of new generation.
Embodiment 1:System 33Ni-28Al-30Cr-4Mo-5Ta intermetallic compound
According to composition is that 33Ni-28Al-30Cr-4Mo-5Ta (atomic percent) prepares burden, and its purity of raw materials is 99.999%.
Adopt non-consumable arc furnace melting 33Ni-28Al-30Cr-4Mo-5Ta alloy cast ingot, vacuum tightness 5 * 10
-3Pa, 3000 ℃ of smelting temperatures turn refining 4 times, and the raw material melting evenly gets final product.
Adopt the high-temperature heat treatment stove to cool to room temperature with the furnace after 12 hours the intermetallic compound bar that makes in insulation under 1200 ℃.
Adopt the 33Ni-28Al-30Cr-4Mo-5Ta ingot of wire cutting method after the thermal treatment to cut diameter 6mm, the right cylinder sample of height 9mm and the square body of 6mm * 6mm * 30mm carry out Mechanics Performance Testing.
Adopting 1111 type tolerance range is 10
-4The mass M of the electronic balance measure sample of g, using tolerance range is 10
-2The end face diameter D and the length L of the vernier caliper measurement sample of mm adopt formula: ρ=4M * D-2 * (π L)
-1Calculate 33Ni-28Al-30Cr-4Mo-5Ta intermetallic compound density p (π is a pi in the formula), its density is 6.26g/cm
3
See also shown in Figure 1ly, adopt MTS-880 type universal material experimental machine to carry out Mechanics Performance Testing, the yield strength in the time of 25 ℃ is 1800MPa, and compression plasticity is greater than 15%; 500 ℃ of yield strengths are 1050MPa, and compression plasticity is greater than 25%; 600 ℃ of yield strengths are 820MPa, and compression plasticity is greater than 26%; 800 ℃ of yield strengths are 580MPa, and compression plasticity is greater than 35%; 1150 ℃ of yield strengths are 180MPa.
Embodiment 2:System 33Ni-30Al-30Cr-4Mo-3Ta intermetallic compound
According to composition is that 33Ni-30Al-30Cr-4Mo-3Ta (atomic percent) prepares burden, and its purity of raw materials is 99.999%.
Adopt non-consumable arc furnace melting 33Ni-30Al-30Cr-4Mo-3Ta alloy cast ingot, vacuum tightness 3 * 10
-3Pa, 2700 ℃ of smelting temperatures turn refining 6 times, and the raw material melting evenly gets final product.
Adopt the high-temperature heat treatment stove to cool to room temperature with the furnace after 12 hours the intermetallic compound bar that makes in insulation under 1200 ℃.
The Mechanics Performance Testing condition of 33Ni-30Al-30Cr-4Mo-3Ta intermetallic compound is identical with embodiment 1, and its density is 6.28g/cm
3Referring to shown in Figure 2, among the figure, the yield strength in the time of 25 ℃ is 1380MPa, and compression plasticity is greater than 20%; 800 ℃ of yield strengths are 450MPa, and compression plasticity is greater than 35%; 1150 ℃ of yield strengths are 150MPa.
Embodiment 3:System 33Ni-25Al-30Cr-4Mo-8Ta intermetallic compound
According to composition is that 33Ni-25Al-30Cr-4Mo-8Ta (atomic percent) prepares burden, and its purity of raw materials is 99.999%.
Adopt non-consumable arc furnace melting 33Ni-25Al-30Cr-4Mo-8Ta alloy cast ingot, vacuum tightness 4 * 10
-3Pa, 3000 ℃ of smelting temperatures turn refining 4 times, and the raw material melting evenly gets final product.
Adopt the high-temperature heat treatment stove to cool to room temperature with the furnace after 12 hours the intermetallic compound bar that makes in insulation under 1200 ℃.
The Mechanics Performance Testing condition of 33Ni-25Al-30Cr-4Mo-8Ta intermetallic compound is identical with embodiment 1, and its density is 6.51g/cm
3Referring to shown in Figure 3, among the figure, the yield strength in the time of 25 ℃ is 1880MPa, and compression plasticity is greater than 15%; 800 ℃ of yield strengths are 720MPa, and compression plasticity is greater than 35%; 1150 ℃ of yield strengths are 210MPa.
Embodiment 4:System 33Ni-23Al-30Cr-4Mo-10Ta intermetallic compound
According to composition is that 33Ni-23Al-30Cr-4Mo-10Ta (atomic percent) prepares burden, and its purity of raw materials is 99.999%.
Adopt non-consumable arc furnace melting 33Ni-23Al-30Cr-4Mo-10Ta alloy cast ingot, vacuum tightness 3 * 10
-3Pa, 2700 ℃ of smelting temperatures turn refining 6 times, and the raw material melting evenly gets final product.
Adopt the high-temperature heat treatment stove to cool to room temperature with the furnace after 12 hours the intermetallic compound bar that makes in insulation under 1200 ℃.
The Mechanics Performance Testing condition of 33Ni-23Al-30Cr-4Mo-10Ta intermetallic compound is identical with embodiment 1, and its density is 6.69g/cm
3Referring to shown in Figure 4, among the figure, the yield strength in the time of 25 ℃ is 1700MPa, and compression plasticity is greater than 15%; 800 ℃ of yield strengths are 850MPa, and compression plasticity is greater than 35%; 1150 ℃ of yield strengths are 305MPa.
Following table is that the intermetallic compound of different components is in vacuum tightness 4 * 10
-3Mechanical property under Pa, 3000 ℃ of smelting temperatures, 5 conditions of turning refining:
Intermetallic compound |
Density (g/cm
3)
|
Yield strength in the time of 1150 ℃ (MPa) |
Yield strength in the time of 25 ℃ (MPa) |
Ni-27Al-30Cr-4Mo-6Ta |
6.44 |
200 |
1600 |
Ni-24Al-30Cr-4Mo-9Ta |
6.55 |
231 |
1840 |
Ni-20Al-30Cr-4Mo-13Ta |
6.79 |
278 |
2200 |
The inventor is by suitably reducing the Al constituent content near the composition range 33Ni-20~32Al-30Cr-4Mo-1~13Ta intermetallic compound eutectic point and adding the Ta element NiAl-Cr (Mo) two-phase alloys has been carried out modification, by Ta element and NiAl intensive Laves (Cr
2Ta) form trend mutually, introduce the hot strength that suitable Laves comes further to improve eutectic alloy mutually on the basis of the NiAl-Cr of rich Ni (Mo) two-phase structure preferably in temperature-room type plasticity and toughness.