Nickel alloy

A nickel-base alloy having the following composition (in atomic percent unless otherwise stated):

• Cr 11.7-16.9;
• Co 1.7-8.75;
• Fe 0-6.2;
• Si 0-1.36;
• Mn 0-0.7;
• Mo 0.2-1.4;
• W 0.7-1.4;
• Al 5.8-8.8;
• Nb 0.63-2.65;
• Ti 1.2-3.7;
• Ta 0.6-1.6;
• Hf 0-0.2;
• C 0.1-0.29;
• B 0.08-0.19;
• Zr 0.022-0.071;
• S<20 ppm, P<60 ppm;
• the balance being Ni and incidental impurities.

A method of making a nickel-base alloy, the method comprising the steps of:

• a) producing a forging by a powder metallurgy technique, using powder having the composition of any one of the preceding claims;
• b) solution heat treating the forging above the γ′ solvus temperature so as to grow the average grain size to ASTM 8 to 6 (22 to 45 μm) throughout, while preventing individual grains from growing to sizes greater than ASTM 2 (180 μm);
• c) quenching the forging from the solution heat treatment temperature to room temperature by forced cooling or fan air cooling;
• d) performing stabilisation/stress relief and precipitation heat treatments at a temperature between 800° C. and 870° C. for between 2 and 16 hours.