Composition-dependent shuffle-shear coupling and shuffle-regulated strain glass transition in compositionally modulated Ti-Nb alloys
Composition-dependent shuffle-shear coupling and shuffle-regulated strain glass transition in compositionally modulated Ti-Nb alloys
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成分调制的 Ti-Nb 合金中成分相关的洗牌剪切耦合和洗牌调节的应变玻璃化转变
DOI：
10.1016/j.actamat.2023.118697
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发表时间：
2023
期刊：
影响因子：
9.4
通讯作者：
Yunzhi Wang
中科院分区：
文献类型：
--
作者：
Yunting Su;Chuanxin Liang;Xun Sun;Hualei Zhang;Qianglong Liang;Yufeng Zheng;Yulin Hao;Rui Yang;Dong Wang;Dipankar Banerjee;Yunzhi Wang
在亚稳β-Ti合金中，无热纯洗牌O′纳米畴是一种常见的结构状态。本文通过热力学数据库、第一性原理计算、相场模拟和实验，揭示了Ti-Nb合金中混排（O′）和剪切（α″，正交马氏体）纳米畴之间的耦合随Nb含量的变化规律。特别是，我们的第一性原理计算表明，随着Nb浓度的增加，相变路径从β → α″转变为β → O′，基于现有热力学数据库的CALPHAD计算表明，Ti-Nb中存在较大的亚稳介导能隙。基于这些发现，我们的相场模拟展示了由调幅分解产生的成分调制Ti-Nb合金中O′和α″纳米畴的形成和冷却时的演变以及相应的转变行为。最后，我们的实验表征表明，在O′/α″纳米畴边界的洗牌分量的连续变化。新的微观结构状态和他们独特的相变路径导致一个前所未有的连续相变行为伴随着超弹性几乎为零滞后和小的残余应变在很宽的温度范围内，所有这些都已在实验中观察到。这种独特的转变行为冷却后，可以很好地表征为洗牌调节应变玻璃化转变。本研究可提供新的见解，在合金设计中，利用成分依赖的洗牌剪切耦合过程中的结构相变。
Athermal pure shuffle O′ nanodomains have been reported as a common structural state in metastable β-Ti alloys. In this study, by integrating thermodynamic databases, first-principles calculations, phase field simulations, and experiments, we reveal the coupling between the shuffle (O′) and shear (α″, orthorhombic martensite) nanodomains as a function of Nb concentration in Ti-Nb alloys. In particular, our first-principles calculations suggest a change in the phase transformation path from β → α″ to β → O′ as the Nb concentration increases, and our CALPHAD calculations based on the available thermodynamic database show a large metastable miscibility gap in Ti-Nb. Informed by these findings, our phase field simulations demonstrate how the O′ and α″ nanodomains form and evolve upon cooling in compositionally modulated Ti-Nb alloys produced by spinodal decomposition and the corresponding transformation behavior. Finally, our experimental characterization shows a continuous change of the shuffle component across the O′/α″ nanodomain boundaries. The novel microstructural states and their unique phase transformation path lead to an unprecedented continuous transformation behavior accompanied by superelasticity with almost zero hysteresis and small residual strain over a wide temperature range, all of which have been observed in the experiments. This unique transformation behavior upon cooling can be well characterized as a shuffle-regulated strain glass transition. This study could provide new insight in alloy design by utilizing composition-dependent shuffle-shear coupling during a structural phase transformation.