Phase-transformation assisted twinning in Molybdenum nanowires

Abstract

Systematic molecular dynamics simulations were conducted to investigate deformation mechanisms in molybdenum (Mo) nanowires (NWs) under uniaxial tensile and compressive loading, and their correlations with bulk materials containing crack tips. Our study revealed striking, orientation-dependent phase transformation and slip/twinning mechanisms. Specifically, 〈100〉-loaded structures exhibited a unique bcc1-fcc-bcc2 phase transition with twin boundary formation, while 〈110〉-loaded structures showed phase transformation under compression but not tension. 〈111〉-loaded structures displayed no phase transformation-assisted twinning, deforming solely by slip. Bulk structures with cracks exhibited similar behavior, underscoring the high stresses needed to activate phase transformations. Density Functional Theory (DFT) calculations confirmed the metastability of the fcc phase, critical for twin formation and bcc phase reorientation. These findings highlight the potential for designing stronger, more ductile Mo-based nanomaterials, opening new avenues for advanced applications in nanotechnology and materials science.