单晶铱取向有关的拉伸变形行为的原子尺度模拟

Atomistic Simulation of the Orientation-dependent Tension Deformation Behavior of Single Crystal Iridium

摘要:

单晶铱同其它面心立方金属相比表现出反常的变形行为,其本征变形断裂机制仍存在争议。本文进行分子动力学模拟研究了单晶铱在1 K下沿[100]、[110]和[111]取向的拉伸变形行为。研究结果表明：单晶铱在三个取向应力-应变曲线上的变形行为差异明显。由于变形机制不同,包括弹性模量、屈服强度、抗拉强度以及延伸率在内的的力学性能在几个拉伸取向上或多或少存在差异。在拉伸载荷作用下,[100]取向单晶铱变形主要通过位错滑移还有少量空位聚集；[110]取向的塑性变形由堆垛层错引起；而 [111]取向单晶铱断裂前产生的塑性变形量很少。

Abstract:

Single crystal iridium exhibits anomalous deformation behaviors in contrast to other fcc-metals and its intrinsic deformation mechanism remains controversial. To investigate the deformation behaviors and underlying deformation mechanisms with respect to crystallographic orientations in single crystal iridium, molecular dynamics simulations were performed at 1 K. Bulk single crystal iridium with different loading axis orientations of [100], [110] and [111] has been considered in current study. Atomic simulation results showed that the on the stress–strain curves differed significantly between crystallographic orientations. And the mechanical properties including elastic modulus, yield stress, ultimate tensile stress and elongation more or less differed between crystallographic orientations owing to different deformation mechanisms. Under tensile loading, [100] oriented single crystal iridium deformed predominantly by dislocations glide with partial vacancies coalescence involved, while plastic deformation in [110] oriented single crystal iridium was initiated by stacking faults. Nevertheless, [111] oriented single crystal iridium underwent little plastic deformation before breaking.