In situ quantitative study of plastic strain-induced phase transformations under high pressure: Example for ultra-pure Zr
In situ quantitative study of plastic strain-induced phase transformations under high pressure: Example for ultra-pure Zr
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DOI：
10.1016/j.actamat.2020.06.015
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发表时间：
2020-09-01
期刊：
影响因子：
9.4
通讯作者：
Levitas, Valery I.
中科院分区：
文献类型：
--
作者：
Pandey, K. K.;Levitas, Valery I.
以超纯、强塑性预变形 Zr 中的 α-omega PT 为例，在旋转金刚石砧室 (RDAC) 的不同压缩-剪切路径下，首次进行了塑性应变诱导相变 (PT) 的原位定量同步加速器 X 射线衍射 (XRD) 研究。测量了每个相和混合物中压力的径向分布以及 omega-Zr 的浓度，所有这些均在样品厚度上进行平均，并测量了厚度分布。应变引起的 α - omega PT 的最小压力 p(epsilon)(d)=1.2 GPa，比静压载荷下小 4.5 倍，比相平衡压力小 3 倍；它与压缩-剪切应变路径无关。理论预测的塑性应变控制动力学方程得到验证和量化；它与压力低于 p(epsilon)(d) 时的压力-塑性应变加载路径和塑性变形无关。因此，DAC 中压缩下的应变诱导 PT 和 RDAC 中扭转下的应变诱导 PT 没有根本区别。使用硬度和 X 射线峰展宽估算两相的屈服强度；接触摩擦应力无法达到剪切屈服强度，因此无法使用压力梯度进行评估。所获得的结果为应变诱导的 PT 和反应的定量研究及其在材料合成和加工、机械化学和地球物理学中的应用开辟了新的机会。 (C) 2020 Acta Materialia Inc. 由 Elsevier Ltd 出版。保留所有权利。
The first in situ quantitative synchrotron X-ray diffraction (XRD) study of plastic strain-induced phase transformation (PT) has been performed on alpha - omega PT in ultra-pure, strongly plastically predeformed Zr as an example, under different compression-shear pathways in rotational diamond anvil cell (RDAC). Radial distributions of pressure in each phase and in the mixture, and concentration of omega-Zr, all averaged over the sample thickness, as well as thickness profile were measured. The minimum pressure for the strain-induced alpha - omega PT, p(epsilon)(d)=1.2 GPa, is smaller than under hydrostatic loading by a factor of 4.5 and smaller than the phase equilibrium pressure by a factor of 3; it is independent of the compression-shear straining path. The theoretically predicted plastic strain-controlled kinetic equation was verified and quantified; it is independent of the pressure-plastic strain loading path and plastic deformation at pressures below p(epsilon)(d). Thus, strain-induced PTs under compression in DAC and torsion in RDAC do not fundamentally differ. The yield strength of both phases is estimated using hardness and x-ray peak broadening; the yield strength in shear is not reached by the contact friction stress and cannot be evaluated using the pressure gradient. Obtained results open a new opportunity for quantitative study of strain-induced PTs and reactions with applications to material synthesis and processing, mechanochemistry, and geophysics. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.