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Tensile Deformation Behaviors and Damage Mechanisms of SRR99 Superalloy Bicrystals with Different Grain Boundary Misorientations
Author(s) -
Zhu Gang,
Liu Feng,
Li Xiaoyang,
Pang Jianchao,
Zhang Zhenjun,
Li Peng,
Zhou Yizhou,
Zhang Zhefeng
Publication year - 2019
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.201800856
Subject(s) - misorientation , materials science , ultimate tensile strength , grain boundary , superalloy , lüders band , slip (aerodynamics) , composite material , elongation , deformation (meteorology) , cracking , transgranular fracture , carbide , fracture (geology) , metallurgy , intergranular fracture , microstructure , physics , thermodynamics
To understand the intrinsic tensile influence mechanisms of grain boundary (GB) misorientations, SRR99 bicrystal superalloys with the different misorientation angles ( Δ θ ) of 4°, 10°, 16°, and 18° are prepared to carry out conventional and in situ tensile tests at room temperature and fracture feature analysis. With the increment of Δ θ , tensile strength and elongation to fracture show successive decrement. The fracture features exhibit two types (4° and 10°–18°): (I) when Δ θ equals to 4°, the cracks initiate and propagate along slip bands (SBs)‐matrix interface. (II) As Δ θ ranges from 10° to 18°, the cracks initiate along the carbide–matrix interface at GBs. Interestingly, the main crack in 10° bicrystal propagates first along the GB then along the SB, but completely along the GB in 16°–18° bicrystals. The former one is absolutely controlled by SBs, and the latter is dominated by carbides and GBs. Finally, a new parameter, defined as the cracking threshold value ( C t h), is proposed to explain the tensile deformation behaviors and damage mechanisms. The new findings will beneficially provide research foundation for the further understanding fatigue damage mechanisms at high temperature.