Molecular dynamics simulation of temperature effect on tensile mechanical properties of single crystal tungsten nanowire

Abstract

High-purity single crystal tungsten nanowire was prepared by the metal-catalyzed vapor-phase reaction method, which was firstly proposed by our research group. Its tensile stress–strain curves and microscopic deformed structures at different temperatures were simulated by molecular dynamics method, in order to study the effects of temperature on its tensile mechanical properties and failure mechanisms. Research results show that the stress–strain curves can be all divided into five stages: elastic, damage, phase transition (dominant), hardening and failure stages. Elastic modulus, tensile strength and strain of phase transition are decreased with increase of temperature, while hardening peak stress is first increased and then decreased. There exists a critical temperature Tc for its phase transition mechanism. When T⩽Tc, the phase transition occurs in one direction and leads to less damage and random failure in its damage zone. When T>Tc, the phase transition occurs in two directions and leads to more damage (twin plane) and failure in its twin plane. That is quite different from FCC metal, where there is only one direction of phase transition.