【摘要】 单晶铱与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1K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3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。更多还原

【Abstract】 Single crystal iridium exhibits anomalous deformation behaviors in contrast to other fcc-metals and its intrinsic deformation mechanism is still controversial. To investigate the deformation behaviors and underlying deformation mechanisms with respect to crystallographic orientations in single crystal iridium, the molecular dynamics simulations were performed at 1 K to simulate the tensile deformation behavior of bulk single crystal iridium in different loading axis orientations of [100], [110] and [111]. Atomic simulation results show that the stress-strain curves differ significantly in three crystallographic orientations. And the mechanical properties including elastic modulus, yield stress, ultimate tensile stress and elongation are more or less different in different crystallographic orientations owing to different deformation mechanisms.Under tensile loading, [100] oriented single crystal iridium deforms predominantly by dislocation slide and partial vacancy coalescence, while plastic deformation in [110] oriented single crystal iridium is initiated by stacking faults. Nevertheless,[111] oriented single crystal iridium undergoes little plastic deformation before breaking.更多还原