Rate-temperature dependence of tension-compression asymmetry in metal matrix composites: Mechanism and damage-coupled constitutive modeling

Abstract

The lack of an insight on micro-mechanisms and constitutive models for the tension-compression asymmetry (TCA) in lightweight metal matrix composites is a major impediment to accurate structural assessment and full exploitation of their application potential, and has attracted growing interest in recent research. This paper aims to report our innovative work on the mechanism investigation and constitutive modeling of the rate-temperature dependence of TCA in TiB₂/2024 Al composite. Experimental results indicate that the TCA extent in both yield stress and strain hardening increases notably with both strain rate and temperature. Microscopic characterizations demonstrate that TCA is primarily attributed to the variation of damage evolution under different deformation paths. Matrix damage always dominates in compression, while damage evolution under tensile loadings is more complex. As temperature increases, the dominant damage mode in tension transits from particle cracking to interface debonding. These tensile damages in high-strain-rate tests will initiate earlier and are distributed over a larger deformed area. Based on the new insights towards damage evolution mechanism, a damage-coupled viscoplastic constitutive model considering the stress state effect was established to quantify TCA over wide ranges of strain rate and temperature, which can be extended and applied to other metal matrix composites.