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| Discussion on mechanism of eliminating prior particle boundary in powder
metallurgy superalloy |
| ZHANG Mengdi1，2，LIU Jiantao1，2，3，ZHANG Yiwen1，2，3，XING Pengyu1，2，3，JIA Jian1，2，3 |
| 1Central Iron and Steel Research Institute, High Temperature Material Institute, Beijing 100081, China;
2 Beijing CISRI-Gaona Materials Technology Co., Ltd., Beijing 100081, China; 3Beijing Key Laboratory of
Advanced High Temperature Materials, Central Iron and Steel Research Institute, Beijing 100081, China |
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Abstract SEM and TEM were used to study types and composition of carbides inside superalloy powder particles
and alloys. The thermodynamic software was used to calculate the composition of carbides in FGH4096 with different
Hf contents. Results showed that precipitates on the prior particle boundary(PPB) in the studied PM superalloy
were mainly MC-type carbides of TiC, and the solubility of MC-type carbides (TiC,ZrC,HfC,NbC,TaC) in nickelbased
superalloys was in the order of TiC>NbC>TaC>ZrC>HfC. The solubility of TiC in FGH4096 is higher than
that of HfC. During the rapid solidification process of atomized powders, the precipitation of carbides in FGH4096
alloy with Hf is greater than that without Hf, and the HfC uniformly nucleate in the whole powder. In the process
of hot isostatic pressing, the binding force of Hf and C is strong, thus forming the HfC. Finally, the (Hf,Ti,Nb)C is
formed in FGH4096 so that the C element can not diffuse to the surface of powder particles to form the TiC, avoiding
the formation of PPB. The mechanism of Zr to eliminate the PPB in FGH4096 is the same as Hf.
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Received: 12 August 2020
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2021, Vol. 31 
