Effects of composition ratio and crystal orientation on nanoindentation behavior of monocrystal AuPt alloys

Abstract

Abstract The improvement of hardness and plasticity for material has been a significant challenge. This work employs molecular dynamics simulations to investigate the nanoindentation behavior of monocrystal AuPt alloys. The enhancement in both the hardness and plasticity of the alloy could be achieved by adjusting the crystal orientation and the composition ratio. For the alloy, the dislocation density notably rises with an increase in Au content, becoming pronounced when it reaches 73%. The high dislocation density at this specific composition ratio leads to the strong work hardening, thereby strengthening the hardness of the Au0.73Pt0.27 alloys. Moreover, the active dislocation motion in the Au0.73Pt0.27 alloy during plastic deformation implies its excellent plasticity. Notably, the hardness of the Au0.73Pt0.27 alloy with [001] crystal orientation is considerably greater relative to other crystal orientations. This is attributed to the propensity for twinning to occur in the Au0.73Pt0.27 alloy with the [ 001 ] crystal orientation, which triggers intensified twin boundary strengthening. This work provides valuable insights for the design of AuPt alloys with superior mechanical properties, broadening their scope for application.