Yuli GU
金属学报(英文版)
Thermo-mechanical fatigue (TMF) behavior of FGH96, a nickel-base powder metallurgy superalloy, has been studied under tension-tension loading at the temperature range from 550℃ to 720℃. The results show that TMF fracture mode is intergranular for the in-phase (IP), but transgranular cleavage-like for the out-of-phase (OP) samples. The total content of Al, Ti and Nb in the γ' phases for the IP or OP samples and the partitioning ratio of γ'/γ in these elements for the IP samples are relatively higher at the lower strain amplitude, which is consistent with the case of the γ' size that is larger at the lower strain amplitude, the lattice parameter misfit is negative and the absolute value is lower at the lower strain amplitude that is correlative with the change of the γ' morphology. The deformation at the lower strain amplitude is mainly dominated by the dislocation lines and dislocation pairs in the matrix channels, at the higher strain amplitude dominated by the large numbers of superlattice stacking faults within the γ' phases.
关键词:
Nickel-base superalloy
,
thermo-mechanical fatigue
,
elemental partitioning
,
γ′ size
,
dislocation （镍基高温合金
,
热机械疲劳
,
元素分配
,
γ′尺寸
,
位错）
徐涛
,
高行山
,
温志勋
,
岳珠峰
稀有金属材料与工程
在晶体塑性理论的基础上,提出了一种适用于镍基单晶高温合金热机械疲劳的本构模型,并采用该模型对单晶材料不同晶体取向的热机械疲劳力学响应进行有限元模拟.结果表明,该本构模型可以较好地模拟镍基单晶合金的热机械疲劳行为.对于同相位热机械疲劳,压缩应力幅大于拉伸应力幅,循环平均应力小于零;对于反相位热机械疲劳,拉伸应力幅大于压缩应力幅,循环平均应力大于零.随着循环次数的增加,材料呈现出在高温半周为初始软化,低温半周为初始硬化的特征.晶体取向对于材料的热机械疲劳性能具有显著的影响.
关键词:
镍基单晶
,
晶体塑性
,
热机械疲劳
,
本构模型
