Influence of Substituting W for Nb or Hf on Solidification Behavior of a Typical Co-Ni-Al-W Based Superalloy  

作　　者：Huifang Zhang Jun Xie Qi Li Hao Wu Jinjiang Yu Hongyu Chai Fengjiang Zhang Jinguo Li Yizhou Zhou Xiaofeng Sun 

机构地区：[1]Shi-Changxu Innovation Center for Advanced Materials,Institute of Metal Research,Chinese Academy of Sciences,Shenyang,110016,China [2]School of Materials Science and Engineering,University of Science and Technology of China,Hefei,230026,China

出　　处：《Acta Metallurgica Sinica(English Letters)》2024年第11期1907-1920,共14页金属学报（英文版）

基　　金：supported by the National Key Research and Development Program of China(2023YFB3712003);the National Science and Technology Major Project(J2019-VI-0018-0133);the AECC Independent Innovation Special Fund Project(ZZCX-2022-040);the National Natural Science Foundation of China(Nos.51701212,51771191 and 51971214);the Youth Innovation Promotion Association Project,Chinese Academy of Sciences(2020198)。

摘　　要：Understanding the effects of various elements on solidification behavior is crucial for designing the composition ofγ’-strengthened Co-based superalloys and is fundamental for controlling the as-cast structure and formulating subsequent heat treatment processes.This research investigated the effects of replacing 1 at.%W with 1 at.%Nb or Hf elements on the solidification behavior of Co-Ni-Al-W-based superalloys.The findings revealed that substituting W with Nb and Hf resulted in a notable decrease in both the solidus temperature(TS)and liquidus temperature(TL).Specifically,the substitution of W with Nb lowered TS from 1353℃ to 1332℃ and TL from 1383℃ to 1368℃,while replacing W with Hf decreased TS from 1353℃ to 1330℃ and TL from 1383℃ to 1366℃.Moreover,both Nb and Hf element are positive segregation element,while Nb decreases and Hf increases W segregation,respectively.During the final solidification stage,the substitution of W with Nb resulted in the formation of eutectic(γ+γ’),Co_(3)Ta,and a small amount ofμ-Co7Nb6 phase,while replacing W with Hf resulted in the formation of the Laves phase andβ-CoAl phase.The solidification paths of the three alloys were confirmed based on the result of differential scanning calorimetry,isothermal solidification experiment and Thermo-calc simulation.These results offer a theoretical basis for the composition design and optimization of heat treatment processes for Co-Ni-Al-W-based superalloys.

关 键 词：Co-Ni-Al-W-based superalloys Solidification microstructure Segregation Solidification path 

分 类 号：TG132.3[一般工业技术—材料科学与工程] TG665[金属学及工艺—合金]