MORPHOLOGICAL INSTABILITY OF γ' PHASE IN NICKEL-BASED POWDER METALLURGY SUPERALLOYS
HU Benfu1), LIU Guoquan1, 2), WU Kai1), TIAN Gaofeng1)
1) School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083
2) State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083
Cite this article:
HU Benfu LIU Guoquan WU Kai TIAN Gaofeng. MORPHOLOGICAL INSTABILITY OF γ' PHASE IN NICKEL-BASED POWDER METALLURGY SUPERALLOYS. Acta Metall Sin, 2012, 48(3): 257-263.
Abstract The morphological evolution and its regularity of γ' precipitates in the low mismatch alloys powder metallurgy (P/M) FGH98I and FGH96 under different heat treatment conditions were studied systematically. The results show that the morphological instability of γ' phase can be summarized as the splitting and unstable protrusion. The splitting of γ' phase is caused by the interaction of anisotropic elastic strain field between γ' phase and $\gamma$ matrix which is rich in solute atoms. While the irregular morphology of unstabe protrusion is mainly due to the concentration changes of solute atoms in the matrix or in the local places along grain boundaries, leading to the non-equilibrium growth of γ' phase. The coexist phenomenon of splitting and unstable protrusion, the formation mechanism of fan type structure induced by discontinous precipitation are discussed respectively.
Supported by National Defence Pre-research Funds (No.9140A12070507QT0202) and High Technology Research and Development Program of China (No.2007AA03A223)
