Influence of Strain Rate on the Effect of Plasticization of High-Strength Ultrafine-Grained Al-Cu-Zr Alloy

Abstract

The influence of the strain rate on the plasticization effect (PE) of ultrafine-grained (UFG) Al-1.47Cu-0.34Zr (wt%) alloy structured by high pressure torsion. A significant increase in plasticity (more than 2 times) while maintaining a high level of strength (ultimate tensile strength ~465 MPa) in the UFG alloy was achieved as a result of additional deformation-heat treatment (DHT), consisting of low-temperature annealing and a small additional deformation. It is shown that the PE after DHT is retained when the strain rate changes from 10-4 to 10-3 s-1 and decreases by half with its further increase to 10-2 s-1. The values of the strain-rate sensitivity coefficient for the UFG Al-1.47Cu-0.34Zr (wt%) alloy were determined in both states before and after DHT. Possible reasons of the PE suppression at high strain rates (≥10-2 s-1) are discussed. Keywords: aluminum alloys, severe plastic deformation, ultrafine-grained structure, strength, plasticity, strain-rate sensitivity.