High temperature low thermal expansion Ni-Mo-Cr alloy
An alloy designed for use in gas turbine engines which has high strength and a low coefficient of thermal expansion is disclosed. The alloy may contain in weight percent 7% to 9% chromium, 21% to 24% molybdenum, greater than 5% tungsten, up to 3% iron, with a balance being nickel and impurities. The alloy must further satisfy the following compositional relationship: 31.95<R<33.45, where the R value is defined by the equation: R =2.66Al+0.19Co+0.84Cr−0.16Cu+0.39Fe+0.60Mn+Mo+0.69Nb+2.16Si+0.47Ta+1.36Ti+1.07V+0.40W The alloy has better hardness after being age-hardened at 1400° F. (760° C.) if tungsten is present from greater than 5% up to 10% and a preferred density if the alloy contains greater than 5% up to 7% tungsten.
1. A nickel-molybdenum-chromium-tungsten based alloy which becomes harder after a 48-hour heat treatment at 1400° F. and then has a Rockwell C hardness of at least 23, the alloy having a composition comprised in weight percent of:
7 to 9
chromium
21 to 24
molybdenum
greater than 5
tungsten
up to 3
iron
up to 0.8
copper
with a balance of nickel and impurities, the alloy further satisfying the following compositional relationship:
31.95 <R< 33.45
where the R value is defined by the equation:
R= 2.66Al+0.19Co+0.84Cr−0.16Cu+0.39Fe+0.60Mn+Mo+0.69Nb+2.16Si+0.47Ta+1.36Ti+1.07V+0.40W.
2. The alloy of claim 1 , where tungsten is present from greater than 5 up to 10 wt. %.
3. The alloy of claim 1 , where tungsten is present from greater than 5 up to 7 wt. %.
4. The alloy of claim 1 , where cobalt is present up to 5 wt. %.
5. The alloy of claim 1 , also comprising in weight percent at least one of boron, up to 0.015%, and carbon, up to 0.1%.
6. The alloy of claim 1 , also comprising in weight percent aluminum, less than 0.7%.
7. The alloy of claim 1 , also comprising in weight percent manganese, up to 2%.
8. The alloy of claim 1 , also comprising in weight percent at least one of niobium, less than 0.5%, tantalum, less than 0.5%, and titanium, less than 0.5%.
9. The alloy of claim 1 , also comprising in weight percent silicon, up to 0.5%.
10. The alloy of claim 1 , also comprising in weight percent vanadium, up to 0.5%.
11. The alloy of claim 1 , also comprising at least one element selected from the group consisting of magnesium, calcium, hafnium, yttrium, cerium, and lanthanum, wherein each said element present comprises up to 0.1 weight percent of the alloy.
12. A nickel-molybdenum-chromium-tungsten based alloy which becomes harder after a 48-hour heat treatment at 1400° F. and then has a Rockwell C hardness of at least 23, the alloy consisting essentially of in weight percent:
7 to 9
chromium
21 to 24
molybdenum
greater than 5
tungsten
less than 0.7
aluminum
present up to 0.015
boron
up to 0.1
carbon
up to 0.1
calcium
up to 5
cobalt
up to 0.8
copper
up to 3
iron
up to 0.1
magnesium
up to 2
manganese
less than 0.5
niobium
up to 1
silicon
less than 0.5
tantalum
less than 0.5
titanium
up to 0.5
vanadium
up to 0.1
of a rare earth element
with a balance of nickel and impurities, the alloy further satisfying the following compositional relationship:
31.95 <R< 33.45
where the R value is defined by the equation:
R= 2.66Al+0.19Co+0.84Cr−0.16Cu+0.39Fe+0.60Mn+Mo+0.69Nb+2.16Si+0.47Ta+1.36Ti+1.07V+0.40W.
13. A nickel-molybdenum-chromium-tungsten based alloy which becomes harder after a 48-hour heat treatment at 1400° F. and then has a Rockwell C hardness of at least 23, the alloy consisting essentially of in weight percent:
7 to 9
chromium
21 to 24
molybdenum
greater than 5
tungsten
up to 0.5
aluminum
0.002 to 0.006
boron
0.002 to 0.03
carbon
up to 0.05
calcium
up to 1
cobalt
up to 0.5
copper
up to 2
iron
up to 0.05
magnesium
up to 0.8
manganese
up to 0.2
niobium
up to 0.2
silicon
up to 0.2
tantalum
up to 0.2
titanium
up to 0.2
vanadium
up to 0.05
of a rare earth element
with a balance of nickel and impurities, the alloy further satisfying the following compositional relationship:
31.95 <R< 33.45
where the R value is defined by the equation:
R= 2.66Al+0.19Co+0.84Cr−0.16Cu+0.39Fe+0.60Mn+Mo+0.69Nb+2.16Si+0.47Ta+1.36Ti+1.07V+0.40W.
14. A nickel-molybdenum-chromium-tungsten based alloy which becomes harder after a 48-hour heat treatment at 1400° F. and then has a Rockwell C hardness of at least 23, the alloy consisting essentially of in weight percent:
7.04 to 8.61
chromium
21.08 to 23.59
molybdenum
5.25 to 9.82
tungsten
up to 2.51
iron
up to 0.8
copper
with a balance of nickel and impurities, the alloy further satisfying the following compositional relationship:
32.01 <R< 33.33
where the R value is defined by the equation:
R= 2.66Al+0.19Co+0.84Cr−0.16Cu+0.39Fe+0.60Mn+Mo+0.69Nb+2.16Si+0.47Ta+1.36Ti+1.07V+0.40W.
15. The alloy of claim 14 , also containing up to 5.17 wt. % cobalt.