Effect of dislocation density on the dynamic yield strength of alloys with nanoscale defects under high energy external actions

Abstract

A theoretical analysis of inelastic processes in aged alloys under intense external influences is carried out. The analysis was carried out within the framework of the theory of dynamic interaction of defects. An analytical expression for the dependence of the dynamic yield strength on the dislocation density has been obtained. The reason for the different influence of nanostructural defects on the dislocation motion under high strain rate deformation and quasi-static deformation is determined. It is shown that under high strain rate deformation, nanosized defects affect the nature of the dependence of the dynamic yield strength on the dislocation density. This dependence becomes nonmonotonic and has a minimum. At the minimum point, there is a transition from the dominance of the drag of the dislocation by Guinier-Preston zones to the dominance of its drag by other dislocations. Numerical estimates of the contribution of the Guinier-Preston zones to the yield strength are made. It is shown that at a high concentration of Guinier-Preston zones, this contribution is very significant. Numerical estimates are made of the dislocation density at which the Taylor relation is violated.

Keywords

• high-speed deformation
• dislocations
• guinier-preston zones
• point defects
• nanomaterials
• taylor ratio