Microstructure of Nickel-based superalloys prepared by spark plasma sintering
QIN Zijun1,2, LIU Feng1,2, JIANG Liang1,2
1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, PR China; 2. Powder Metallurgy Research Institute, Central South University, Changsha 410083, China
Abstract：Nickel-base superalloys were sintered by spark plasma sintering (SPS) using the powders of FGH96 fabricated by argon vaporization method as raw material. At the same time, the raw material powder was heat-treated under the same conditions as the SPS process, and the FGH96 superalloy was prepared by hot isostatic pressing (HIP). By analyzing the microstructure and grain size of the alloy at different sintering temperatures or different heat preservation time, the grain orientation and grain size of the alloy fabricated by HIP with heat treatment powder were compared, and the microstructure characteristics of SPS Ni-based superalloy were studied. The results show that the alloy is nearly densified after sintering for 40 min. While the microstructure of the alloy is composed of tiny cellular structure and dendrite crystals when sintered at 1 070 ℃. The carbide precipitates distribute mainly inside the grains with a few on the grain boundaries, which results in almost invisible PPBs. The microstructure of the alloy is composed of equiaxed grains when sintered at 1 170 ℃. The carbide precipitates distribute along the prior particle boundaries, which make quite obvious PPBs. It is indicated that the method of SPS can reduce the PPBs in certain degree, but it had no effect on control the grain size.
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2018, Vol. 23 
