State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan, 410083, China.
Department of Materials Science and Engineering, Northwestern University, Evanston, IL, 60201, USA.
Sci Rep. 2018 Jan 31;8(1):1992. doi: 10.1038/s41598-018-20257-9.
By means of first principles calculation and experiments, a detailed mechanism is proposed to include the stages of slip, adjustment, and expansion for the HCP → FCC phase transformation with the prismatic relation of [Formula: see text] and [Formula: see text] in titanium. It is revealed that the formation of four FCC layers is preferable after the slip of Shockley partial dislocations of 1/6 [Formula: see text] on [Formula: see text] planes, and that the adjustment of interplanar spacing and the volume expansion are energetically favorable and could happen spontaneously without any energy barrier. It is also found that the transformed FCC lattice first follows the c/a ratio (1.583) of HCP and then becomes an ideal FCC structure (c/a = √2). The proposed mechanism could not only provide a deep understanding to the process of HCP → FCC prismatic transformation in titanium, but also clarify the controversy regarding volume expansion of HCP-FCC phase transition of titanium in the literature.
通过第一性原理计算和实验，提出了一个详细的机制，包括钛中 HCP→FCC 相转变的滑移、调整和扩展阶段，具有[公式：见文本]和[公式：见文本]的棱柱关系。结果表明，在[公式：见文本]平面上的 1/6 [公式：见文本]肖克利部分位错滑移后，形成四个 FCC 层是有利的，而且层间距的调整和体积膨胀在能量上是有利的，不需要任何能量障碍就可以自发发生。还发现转变后的 FCC 晶格最初遵循 HCP 的 c/a 比（1.583），然后成为理想的 FCC 结构（c/a=√2）。所提出的机制不仅可以深入了解钛中 HCP→FCC 棱柱形转变的过程，还可以澄清文献中关于钛的 HCP-FCC 相变体积膨胀的争议。
