Characterization and analysis of hot compression behaviors of an ultralight Mg-Li-Al alloy

Abstract

This paper aims at establishing microstructure/property/processing correlations in a thermomechanically processed ultralight Mg-3.5Li-1Al (wt%) alloy. The thermomechanical cycle consists of uniaxial compression at temperatures of 250 °C, 350 °C, and 450 °C and strain rates of 1, 0.1, 0.01, and 0.001/s using a Gleeble® 3500 thermal-mechanical simulation testing system. Upon testing, the samples were quenched, sectioned, and perfectly polished to run nanoindentation tests. The nanoindentation tests were performed to study post-treatment mechanical properties and related phenomena (i.e. Portevin–Le Chatelier effect) at different conditions in the processed samples. Microstructural changes, hot compression stress-strain curves, and nanoindentation load/displacement response are discussed in detail in the present research. The correlations between flow stress, strain rate, and deformation temperature were assessed. Besides, using the Zener-Hollomon parameter, the effects of thermomechanical parameters (temperature and strain rate) on deformation response were analyzed. Keywords: Thermomechanical processing, Mg-3.5Li-1Al alloy, Nanoindentation, Microstructure, Portevin–Le Chatelier effect, Zener-Hollomon parameter