Phase stability dependence of deformation mode correlated mechanical properties and elastic properties in Ti-Nb gum metal
Phase stability dependence of deformation mode correlated mechanical properties and elastic properties in Ti-Nb gum metal
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DOI：
10.1016/j.msea.2017.06.099
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发表时间：
2017-08-15
期刊：
影响因子：
6.4
通讯作者：
Vecchio, Kenneth S.
中科院分区：
文献类型：
--
作者：
Shin, Sumin;Zhang, Cheng;Vecchio, Kenneth S.
研究了累积应变为0.15的亚稳Ti-23Nb-0.7Ta-2Zr-0.80 （at%）合金的微观组织演变和变形模式，采用不同的固溶处理来控制元素分布和bcc β相稳定性。近年来的研究表明，β相特定变形机制的发生与其化学稳定性密切相关。本研究采用Bo-Md相稳定性图评价了β相稳定性，并讨论了固溶处理条件下的变形模式，从而导致不同的变形显微组织。利用电子背散射衍射和x射线衍射对变形组织进行分析，发现变形带不仅由机械诱导的{332}< 112 > β和{112}< 111 > β孪晶组成，而且由应力诱导的马氏体α”相组成。结果表明，合金的变形带数量随着合金的均匀性的增加而减少，这与相组织密切相关，并直接影响合金的硬度和弹性模量等最终性能。根据实验观察结果，变形特征的β相稳定性依赖性可以解释Ti-Nb胶金属在没有明显弹性性能变化的情况下操纵力学性能的可能性。
The evolution of microstructure and deformation modes in metastable Ti-23Nb-0.7Ta-2Zr-0.80 (at%) alloys with accumulated strain to 0.15 are investigated, where different solution treatments were applied to control both elemental distributions and the bcc beta-phase stability. Recent studies suggest that the occurrence of specific deformation mechanism of the beta-phase is strongly linked with its chemical stability. In the present study, the Bo-Md phase stability diagram was used to evaluate the beta-phase stability and to discuss the deformation modes as function of solution treatment conditions, resulting in different deformed microstructures. Analysis of the deformed microstructure using electron backscatter diffraction and X-ray diffraction revealed that deformation bands formed at the initial stage of strain were composed of not only mechanically induced {332} < 112 > beta and {112} < 111 > beta twinning, but also stress-induced martensite alpha" phase. It was observed that the number of deformation bands decreases with increasing homogeneity in the alloy, which is strongly dependent on the phase constitution, and directly impacts its final properties including hardness and elastic modulus. Based on the experimentally observed results, the beta-phase stability dependence of deformation features can explain the possibility of manipulating the mechanical properties without the evident elastic properties variation in Ti-Nb Gum Metal.