Development of Mg-Ca-Mn-Ce wrought alloy with both high strength and high thermal stability

Abstract

In this work, the microstructure and mechanical properties of the as-extruded and as-annealed Mg-0.8Ca-xMn-0.2Ce (x = 0.4, 0.7) wt% alloys, which are named as XME04 and XME07, have been investigated. An ultra-high strength of ~428 MPa can be achieved in as-extruded XME04 sample due to the high proportion of as-deformed grains and also high density of residual dislocations. The high Mn addition in as-extruded XME07 alloy can promote the dynamical recrystallization and induce more nano-precipitations. More nano-Mn precipitates in XME07 alloy can effectively hinder grain growth during extrusion and contribute to the finer grains. As a result, more precipitation of nano-phases, finer grains, and lower density of residual dislocations together account for the higher thermal stability in XME07 alloy than that in XME04 alloy. A novel Mg-0.8Ca-0.7Mn-0.2Ce wt% alloy with an excellent thermal stability has been developed. After annealing at 300 °C for 6 h, the yield strength of this alloy can still maintain at ~322 MPa. The relevant results can provide important guidance for developing novel Mg wrought alloys with both ultra-high strength and also high thermal stability. • Ultra-high strength of ~428 MPa was achieved in the low-cost Mg-0.8Ca-0.4Mn-0.2Ce (wt%) wrought alloy. • The Mn addition can promote dynamical recrystallization and induce more nano-precipitations. • A novel Mg-0.8Ca-0.7Mn-0.2Ce wt% alloy with an excellent thermal stability has been produced.