Achieving high heat-resistant property in dilute Mg-0.2Ce wrought alloy by retarding recrystallization process

Abstract

Conventional heat-resistant Mg alloys always involve a high concentration of rare-earth solutes to produce amounts of thermostable second phases. In this work, however, the high heat resistance is achieved in a dilute Mg-0.2Ce (wt%) alloy, exhibiting a high ultimate tensile strength of ∼ 181 MPa at 250 ℃, which is superior to those of benchmark Mg alloys including ZK60, AZ80 and other rare-earth element containing Mg alloys. The high-temperature strength of present Mg alloy can be attributed to the suppressed recrystallization process due to the minor Ce addition, since the softening mechanism of grain boundary sliding at high-temperature can be effectively suppressed in the elongated un-recrystallized grains and the texture hardening is always effective in the deformed regions. In addition, the present Mg alloy exhibits excellent thermal stability during the long-term heating on account of the sluggish static recrystallized process. The high temperature strength decreases gradually with the annealing time, which can yet exceed 145 MPa after annealing at 300 ℃ for 6 h. Generally, the present work would provide important insight into developing novel low-alloyed and heat-resistant Mg wrought alloys.