Abstract Deformation twinning in coarse-grained fcc metals results from the highly coordinated glide of Shockley partial dislocations with the same Burgers vector on successive {111}-type twinning planes. The main issue of the formation mechanism of deformation twinning is how the arrangement of Shockley partials required for twinning evolves. Here, we present the deformation twinning mechanism that operates in Fe-17Mn-0.45C-1.5Al-1Si TWIP steel by means of in-situ TEM deformation tests and post-mortem TEM characterization. The in-situ TEM observation shows the formation of a thin twin by Shockley partial dislocations generated in a grain boundary, which indicates the nucleation of deformation twins at grain boundary defect sites. The observed twinning process is similar to deformation twinning in nano-crystalline materials through successive emission of partial dislocations from grain boundaries. In addition, a high density of Frank partial dislocations is observed inside deformations twins. These defects affect the growth of deformation twins and could contribute to the high work hardening of TWIP steel.

中文翻译：

---

孪生诱导塑性钢的变形孪生机制

摘要 粗晶面心立方金属中的变形孪晶是由肖克利部分位错在连续 {111} 型孪晶平面上具有相同伯格斯矢量的高度协调滑动引起的。形变孪晶形成机制的主要问题是孪晶所需的肖克利分部的排列如何演化。在这里，我们通过原位 TEM 变形测试和事后 TEM 表征，介绍了在 Fe-17Mn-0.45C-1.5Al-1Si TWIP 钢中起作用的变形孪生机制。原位 TEM 观察显示通过在晶界中产生的肖克利部分位错形成薄孪晶，这表明变形孪晶在晶界缺陷位点处形核。观察到的孪晶过程类似于纳米晶材料中通过从晶界连续发射部分位错的变形孪晶。此外，在变形孪晶内部观察到高密度的 Frank 部分位错。这些缺陷会影响变形孪晶的生长，并可能导致 TWIP 钢的高加工硬化。