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arXiv 2105.04597cond-mat.mtrl-sci
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一种TWIP高熵合金的高温力学性能及相关的组织/织构演变

The high temperature mechanical properties and the correlated microstructure/texture evolutions of a TWIP high entropy alloy

A. Nabizada, A. Zarei-Hanzaki, H. R. Abedi, M. H. Barati, P. Asghari-Rad, H. S. Kim

摘要:

本文研究了一种高熵钛合金在不同温度下的显微组织和织构演变。为此,拉伸试验进行的温度范围从298至873 K下的应变速率为0.001 s-1。实验材料表现出非凡的室温加工硬化行为,无论是瞬时应变硬化指数和加工硬化速率值。这导致了可接受的极限拉伸强度/延展性平衡,并且考虑到孪生和平面滑移的高活性是合理的。这样的加工硬化能力恶化,在较高的温度下,由于增加位错湮灭率和堆垛层错能值,抑制孪晶形成和位错积累。然而,与其他单相高熵合金相比,加工硬化区的幅度和范围的减少是微不足道的。这是由于该合金在不同变形温度下具有较高的位错储存能力。在773和873 K下观察到锯齿状流动,这是由于动态应变时效(DSA)机制。有趣的是,在这种情况下,DSA机制对整体延性具有有益的影响,这归因于应变硬化指数的增加导致颈缩的延迟。织构检验还揭示了由于孪晶和八面体滑移的同时贡献而形成的双纤维织构。

英文摘要:

The present work deals with the microstructure and texture evolutions of a TWIP high entropy alloy at various temperatures. Toward this end, the tensile tests were conducted at temperatures ranging from 298 to 873 K under the strain rate of 0.001s-1. The experimented material exhibited an extraordinary room temperature work hardening behavior, in respect of both the instantaneous strain hardening exponent and the work hardening rate values. This resulted in an acceptable ultimate tensile strength /ductility balance and was justified considering the high activity of twinning and planar slip. Such work hardening capacity deteriorated at higher temperatures due to increasing the dislocation annihilation rate and the stacking fault energy values that suppressed twin formation and dislocation accumulation. However, the decrease in amplitude and extent of the work hardening region was insignificant compared with other single-phase high entropy alloys. This was attributed to the high capacity of the alloy for dislocation storage at various deformation temperatures. The serrated flow was observed at 773 and 873 K due to the dynamic strain aging (DSA) mechanism. Interestingly, in this case, the DSA mechanism has a beneficial effect on overall ductility, which was attributed to the increase in the strain hardening exponent result in a delay of necking. Texture examination also reveals the formation of a double fiber texture due to the simultaneous contribution of twinning and octahedral slip.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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