Alloy design of a new type high-performance P/M turbine disk superalloy

The effects of alloy elements on the precipitation behaviours of TCP and gamma' phases in new type powder metallurgy (P/M) turbine disk superalloy Rene104 at the aging temperature of 815 degrees C were studied systematically by a thermodynamic calculation method. The chemical compositions of new type nickel-based P/M superalloy were designed combining with d-electron theory. The results show that the contents of Cr, Co, Mo and W mainly influence the precipitation temperature and amount of TCP and gamma' phases in Rene104. The suggested contents of Cr and Co are 13% and 20.6% respectively, and the suggested content of Mo is higher than W. The results also show that the content ratios of Al/Ti and Nb/Ta affect the precipitation behaviours of TCP and gamma' phases. The balance values of Al/Ti and Nb/Ta are suggested in order to make the alloy having desired microstructural stability and strengthening effect. In addition, Hf also influenced the precipitation behaviours of TCP and gamma' phases and the suggested content of Hf is 0.2%. The main precipitates of the new type P/M turbine disk superalloy FGH98I are gamma', MC, M23C6 and M3B2, and no any TCP phases precipitate. After the exposure at 750 degrees C, 815 degrees C and 850 degrees C for 1000 h, the new alloy still shows good microstructural stability.(C) 2011 Published Elsevier Ltd.