亚微米铍纤维中孪晶界面迁移的原位TEM研究
In situ TEM study of twin boundary migration in sub-micron Be fibers
摘要：
六方晶体中的形变孪晶常被认为是弥补独立滑移系缺陷的一种方法。这种机制可能会加剧或关闭在小规模的晶体，其机械行为可以显着偏离散装材料。在这里，我们表明，亚微米铍纤维最初没有位错和拉伸测试原位在透射电子显微镜（TEM）变形的$\{ 10\bar{1}2 \}$ $\langle 10\bar{1}1 \rangle$双增厚。孪晶界的传播速度似乎完全由孪晶位错直接从表面成核所控制。产生的剪切与孪晶位错的重复横向运动相一致。我们表明，激活体积（$V$）与孪晶边界传播可以检索从测量的孪晶边界速度的应力降低，在一个经典的松弛力学测试。$V \approx 8.3 \pm 3.3 \times 10^{-29}m^3$的值与表面成核的预期值相当。
英文摘要：
Deformation twinning in hexagonal crystals is often considered as a way to palliate the lack of independent slip systems. This mechanism might be either exacerbated or shut down in small-scale crystals whose mechanical behavior can significantly deviate from bulk materials. Here, we show that sub-micron beryllium fibers initially free of dislocation and tensile tested in-situ in a transmission electron microscope (TEM) deform by a $\{ 10\bar{1}2 \}$ $\langle 10\bar{1}1 \rangle$ twin thickening. The propagation speed of the twin boundary seems to be entirely controlled by the nucleation of twinning dislocations directly from the surface. The shear produced is in agreement with the repeated lateral motion of twinning dislocations. We demonstrate that the activation volume ($V$) associated with the twin boundary propagation can be retrieved from the measure of the twin boundary speed as the stress decreases as in a classical relaxation mechanical test. The value of $V \approx 8.3 \pm 3.3 \times 10^{-29}m^3$ is comparable to the value expected from surface nucleation.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
