晶体孪晶
材料科学
成核
高温合金
剪切(物理)
叠加断层
复合材料
滑倒
变形(气象学)
合金
变形机理
位错
部分位错
临界切应力
冶金
结晶学
微观结构
热力学
结构工程
工程类
粘度
剪切速率
化学
物理
作者
Zihao Tan,Xinguang Wang,Zhicheng Ge,Yahang Mu,Yongmei Li,J.C. Pang,Xu Tao,Mingke Zou,Yanhong Yang,Jide Liu,Jinlai Liu,Jinguo Li,Yizhou Zhou,Xiaofeng Sun
标识
DOI:10.1016/j.ijfatigue.2023.108086
摘要
The high-temperature and long-term solution heat treatments of fourth-generation single crystal (SX) superalloys have sparked an increasing number of homogenization pores in the alloy. Out-of-phase (OP) thermal-mechanical fatigue (TMF) experiments were conducted to elucidate the effect of pores on the fatigue behaviors and deformation mechanisms. The results showed that the plastic deformation was mainly concentrated upon γ matrix in regions away from pores, more specifically, intrinsic stacking fault (ISF) and extrinsic stacking fault (ESF) as well as dislocation cross-slipping were detected. In areas near micro-pores, however, the γ/γ′-structure was subjected to severe twinning shearing. High-resolution observation illustrated that the amount of ESF and a/6<112> twinning dislocations had remarkably increased. Besides, the partial dislocations were more prone to move in different slipping systems at these regions with considerable stress concentration. These factors collectively enabled the formation of deformation twins from the edge of micro-pores. Moreover, the twinning nucleation could occur near both H-pores and S-pores, while the increasing pore size would enhance the nucleation and propagation of pore-induced twins by a large margin. These findings reported have provided important guidance for the future application of the fourth-generation SX superalloys.
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