Confluent effects of initial dislocation microstructures on yield behavior in single-crystal tungsten at high temperature

Abstract

Though it is well known that initial dislocation microstructures play an important role in the deformation behavior of materials, how dislocation microstructures affect the macroscopic properties is still subjected to intensive research due to their complexity. In this work, we use discrete dislocation dynamics (DDD) to understand the effect of initial dislocation microstructures on the dynamic yield behavior of single-crystal tungsten above the critical temperature (800 K). DDD results suggest that the dislocation source length l_"0" and the dislocation density ρ_"0" are responsible for the initial yield stress and the flow stress of tungsten under dynamic loading, respectively. As ρ_"0" and l_"0" increase, the plastic yield mechanism transforms from dislocation-source activation into dislocation-dislocation interactions, resulting in the initial yield stress decreasing and the flow stress increasing. The confluent effects of ρ_"0" and l_"0" on the steady-state flow stress "σ" _"flow" can be unified by a linear relationship between "σ" _"flow" and 〖√("ρ" _"0" ) "log" 〗⁡("l" _"0" /"2b" ). Our results could be a valuable piece that connects dynamic yield behavior to the initial dislocation microstructures.