Abstract The ability to predict the formation of twin variants during deformation is essential for modelling the mechanical response of a material. The present study aims to provide a criteria for twin variant selection in an α-Zr alloy. Here Zircaloy-4 was uniaxially deformed at 25 and 300 °C to strain of 0.10 leading to formation of { 1 0 1 ¯ 2 } 1 ¯ 0 1 1 tensile twins. Twin variants were characterized using electron backscatter diffraction for their dependency on commonly used geometric factors i.e. Schmid and geometric compatibility factor. It was shown that twin variants do not always form based on a single criterion. Slip traces and their relation to twins in the neighbouring grain were analysed. A probability based ranking approach for twin variant selection considering a combination of both Schmid and geometric compatibility factors is proposed. The approach was based on the probability of the occurrence of two events, (i) occurrence of either slip or twin and (ii) transmission between slip-twin events across the grain boundary. Two mechanisms as consequence of both (i) and (ii) were considered – mechanism A where twin formation is by the activation of either slip or twin system in the neighbouring grain, and mechanism B where active slip to twin or twin to twin transmission takes place across the grain boundary. The fraction of twins formed by mechanism A was seen to be higher than those by Schmid and geometric compatibility factor taken separately.

中文翻译：

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α-Zr合金双变体选择的基于概率的排序方法

摘要 预测变形过程中孪晶变体形成的能力对于模拟材料的机械响应至关重要。本研究旨在为 α-Zr 合金中的双变体选择提供标准。在这里，Zircaloy-4 在 25 和 300°C 下单轴变形到 0.10 的应变，导致形成 { 1 0 1 ¯ 2 } 1 ¯ 0 1 1 拉伸孪晶。使用电子背散射衍射对双变体进行表征，因为它们依赖于常用的几何因素，即 Schmid 和几何兼容性因素。结果表明，双胞胎变体并不总是基于单一标准形成。分析了滑移痕迹及其与相邻晶粒中孪晶的关系。考虑到 Schmid 和几何兼容性因素的组合，提出了一种基于概率的双变体选择排序方法。该方法基于两个事件发生的概率，(i) 滑移或孪生的发生和 (ii) 跨越晶界的滑移-孪生事件之间的传输。考虑了 (i) 和 (ii) 的两种结果——机制 A，其中孪晶形成是通过激活相邻晶粒中的滑移或孪晶系统，以及机制 B，其中主动滑移到孪晶或孪晶到孪晶传输需要放置在晶界上。由机制 A 形成的双胞胎的比例被认为高于 Schmid 和单独采取的几何相容性因子。(i) 滑移或孪晶的发生和 (ii) 跨越晶界的滑移孪晶事件之间的传输。考虑了 (i) 和 (ii) 的两种结果——机制 A，其中孪晶形成是通过激活相邻晶粒中的滑移或孪晶系统，以及机制 B，其中主动滑移到孪晶或孪晶到孪晶传输需要放置在晶界上。由机制 A 形成的双胞胎的比例被认为高于 Schmid 和单独采取的几何相容性因子。(i) 滑移或孪晶的发生和 (ii) 跨越晶界的滑移孪晶事件之间的传输。考虑了 (i) 和 (ii) 的两种结果——机制 A，其中孪晶形成是通过激活相邻晶粒中的滑移或孪晶系统，以及机制 B，其中主动滑移到孪晶或孪晶到孪晶传输需要放置在晶界上。由机制 A 形成的双胞胎的比例被认为高于 Schmid 和单独采取的几何相容性因子。和机制 B，其中主动滑移到孪晶或孪晶到孪晶传输发生在晶界上。由机制 A 形成的双胞胎的比例被认为高于 Schmid 和单独采用的几何相容性因子。和机制 B，其中主动滑动到孪晶或孪晶到孪晶传输发生在晶界上。由机制 A 形成的双胞胎的比例被认为高于 Schmid 和单独采取的几何相容性因子。