Increasing high-temperature fatigue resistance of polysynthetic twinned TiAl single crystal by plastic strain delocalization
Increasing high-temperature fatigue resistance of polysynthetic twinned TiAl single crystal by plastic strain delocalization
复制标题
通过塑性应变离域提高多合成孪晶 TiAl 单晶的高温疲劳性能
DOI：
10.1016/j.jmst.2021.03.050
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发表时间：
2021-05-24
影响因子：
10.9
通讯作者：
Chen, Guang
中科院分区：
文献类型：
--
作者：
Chen, Yang;Cao, Yuede;Chen, Guang
聚合成孪晶TiAl单晶由于具有良好的强度、延展性和抗蠕变性能，在高温领域具有广阔的应用前景。然而，这种材料的高温应用的关键性能包括高温疲劳性能仍然未知。本文研究了PST TiAl单晶的高温高周疲劳性能。结果表明，PST TiAl单晶在975℃下，在270 MPa的应力幅下，可承受10次以上的循环载荷，显著高于传统TiAl合金。实验观察和原子模拟结果表明，合金抗疲劳性能的提高主要归因于均匀片层结构中塑性应变的离域化，且各片层内塑性变形分布均匀且充分。即使在难以滑移的α(2)片层中，也可以观察到大量的层错结构。α(2)中的< c + a >位错倾向于解离成b = 1/6 (2) / barO (3) / bar的Frank偏，形成I1断层带，保证了变形的连续性。(C) 2021年由Elsevier Ltd代表中国金属学会出版。
Polysynthetic twinned (PST) TiAl single crystal possesses great potentials for high-temperature applica-tions due to its excellent combination of strength, ductility and creep resistance. However, a critical property for high-temperature application of such material involving high-temperature fatigue properties re-mains unknown. Here, the high-temperature high-cycle fatigue performance of PST TiAl single crystal has been studied. The result shows that PST TiAl single crystal can withstand more than 10 7 cyclic loadings at 975 degrees C under a stress amplitude of 270 MPa, which is significantly higher than traditional TiAl alloys. Experimental observations and atomistic simulations indicate that the improvement of fatigue resistance is attributed to the plastic strain delocalization in uniform lamellar structure, and the plastic deformation is well-distributed and sufficient in each lamella. Even in the alpha(2) lamella with difficult slippage, a large number of stacking fault structures can be observed. The < c + a > dislocations in alpha(2) tend to dissociate into a Frank partial with b = 1/6 (2) over barO (3) over bar , forming a ribbon of I1 fault which ensures the continuity of deformation. (C) 2021 Published by Elsevier Ltd on behalf of Chinese Society for Metals.