Simultaneously achieving excellent mechanical properties and high thermal conductivity in a high Mn-containing Mg-Zn-Ca-Al-Mn sheet alloy

Abstract

Tensile properties, formability and thermal conductivity of Mg-3Zn-0.5Ca-0.5Al-xMn (x: 0.1–1.5 in wt%) sheet alloys with different Mn contents were investigated. Benefitting from dense Al-Mn nanoscale spherical precipitates, yield strength was significantly enhanced by 39 MPa with increasing the Mn content from 0.1 wt% to 1 wt%. In the meanwhile, excellent formability was maintained with Erichsen values larger than 8 mm. Further increasing the Mn content to 1.5 wt% did not contribute to strengthening due to the formation of coarse β-Mn particles. In spite of larger additive amount, thermal conductivity improved for the 1 wt% Mn added alloy compared to the 0.1 wt% Mn added alloy due to the increased amount of Al-Mn nanoscale spherical precipitates, which reduced a content of Al solute atoms. High strength (average yield strength: 180 MPa), high formability (Erichsen value: 8.5 mm) and high thermal conductivity (133 W/(m K)) were simultaneously achieved in the 1 wt% Mn added alloy.