ABSTRACT

In situ observation of a phase transformation during annealing of Si containing diamond-cubic (dc) and metastable phases has been performed using synchrotron X-ray diffraction. Metastable body-centred-cubic (bc8) and rhombohedral (r8) phases were formed by high-pressure torsion. These metastable phases gradually disappeared when increasing the annealing temperature to ∼ 180°C while another metastable phase having a hexagonal diamond (hd) structure appeared at ∼ 190°C. High-resolution transmission microscopy analysis revealed that hd and dc grains were present after annealing at 200°C. The results indicate that a phase transformation, mainly from bc8 to hd, occurred during annealing.

摘要

已经使用同步加速器X射线衍射对含Si的金刚石-立方相（dc）和亚稳相进行了退火过程中的相变的原位观察。通过高压扭转形成亚稳态的体心立方（bc8）和菱形（r8）相。当将退火温度提高到约180°C时，这些亚稳相逐渐消失，而另一种具有六角形菱形（hd）结构的亚稳相则在约190°C出现。高分辨率透射显微镜分析显示，在200°C退火后，存在hd和dc晶粒。结果表明，在退火过程中发生了相变，主要是从bc8到hd的转变。