Effect of directional solidification process on microstructure and stress rupture property of a hot corrosion resistant single crystal superalloy

作     者：Liang Luo Cheng-bo Xiao Jing-yang Chen Qing Li Sheng-long Dai 

作者机构：Science and Technology on Advanced High Temperature Structural Materials LaboratoryBeijing Institute of Aeronautical MaterialsBeijing 100095China 

出 版 物：《China Foundry》 (中国铸造（英文版）)

年 卷 期：2019年第16卷第1期

页      面：8-13页

核心收录：

学科分类：08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：financially supported by the National Key R&D Program of China(Grant No.2016YFB0701402) National Natural Science Foundation of China(Grant No.51771020) Aeronautical Science Foundation of China(Grant No.2015ZE21006) 

主　　题：DD488 superalloy liquid metal cooling high rate solidification microstructure property 

摘      要：The influences of different directional solidification processes, i.e., the high rate solidification(HRS) and liquid metal cooling(LMC), on microstructure and stress rupture property of DD488 alloy were investigated. The DD488 alloy was directional solidified by both HRS and LMC processes. The microstructure and stress rupture properties at 980 ℃/250 MPa were investigated by using optical microscopy(OM), scanning electron microscopy(SEM), electron microprobe analyzer(EPMA), transmission electron microscopy(TEM) and stress rupture testing. The results indicated that the LMC process refined the primary dendrite arm and decreased the microporosity volume fraction and solidification segregations of Cr and Co in as-cast DD488 alloy. After standard heat treatment of 1,260 ℃/4 h, AC(air cooling) + 1,080 ℃/4 h, AC + 870 ℃/24 h, AC, the γ′ morphology in LMC alloy was more cuboidal than that in HRS alloy, and the γ′ volume fraction of LMC alloy was higher than that of HRS alloy. The stress rupture life at 980 ℃/250 MPa of HRS alloy was 76.8 h, and it increased to 110.0 h in LMC al oy. The LMC process increased the stress rupture life due to the higher γ′ volume fraction, more perfect rafting structure and finer interfacial dislocation networks.