Microstructure, mechanical property and thermal conductivity of Mg-6Gd-1Er-6Zn-0.5Zr alloy sheets

Magnesium (Mg) alloys with integrated structural-functional performance have broad applications in the fields of defense and military industry, transportation and electronic communication, etc. Developing Mg alloy sheets with synergistic mechanical property and thermal conductivity is a key to achieving these applications. The effects of rolling temperature and cumulative strain on the microstructure evolution and mechanical property and thermal conductivity of solid-solution Mg-6Gd-1Er-6Zn-0.5Zr (mass fraction, %, GEZ616K) alloy were investigated. The results show that, as the rolling temperature increasing, the microstructures of the sheet with cumulative deformation strain of 80% undergo transformation process from mixed crystallization at low-temperature to uniform fine recrystallization and grain coarsening at high temperature. At the same time, the basal texture weakens, the proportion of large angle grain boundary increases, and dislocation density in the alloy decreases. At a certain rolling temperature, the number of twins gradually decreases and the proportion of recrystallization gradually increases with the increase of the cumulative strain, resulting in a synchronous improvement of mechanical property and thermal property. The GEZ616K alloy rolled at 425 ℃ with cumulative strain of 80% exhibits the excellent mechanical property and thermal property, the tensile strength, yield strength and elongation are 280 MPa, 227 MPa and 11.4%, respectively, as well as the thermal diffusion coefficient of 72.9 mm2/s and the thermal conductivity of 135.3 W/(m·K). © 2024 Central South University of Technology. All rights reserved.