Temperature-Dependent Mechanical Response of an UFG Aluminum Alloy at High Rates

Abstract

High temperature (298 K-573 K) and high strain rate (4000 s −1 ) compression experiments were performed on a cryomilled ultra-fine grained (UFG) Al-5083 using a modified Kolsky bar with a heating system designed to reduce "cold contact" time. The resulting stress strain curves show a reduction in strength of approximately 300 MPa at the highest temperature tested. This softening has been related to a thermally activated deformation mechanism. In addition, an experimental procedure was developed to investigate the microstructure evolution during the preheating, prior to mechanical loading, so as to identify the intrinsic mechanical response of the material at high temperatures. The results of this procedure are in good agreement with a TEM study on material that has been heated but not loaded.

Compressive behavior and deformation kinetics of ultrafine grained aluminum processed by equal channel angular pressing

“…In this work, by combining the micro-hardness measurement and microstructural observation on short-time annealed UFG-Al, the highest testing temperature was determined to avoid any possibly significant microstructural change due to the heating process. This method is similar to Cottrell-Stokes-type experiments [35]. For more detail of the determination of the highest experimental temperature, please refer to [34].…”