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

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.