Achieving outstanding heat-resistant properties in Mg alloy via constructing stable solute-network

Abstract

A new Mg–Sm–Ce–Mn-based alloying system with a large miscibility gap was uncovered, and multi-solute co-segregations at high-angular grain boundaries (HAGBs), dislocations and low-angular grain boundaries (LAGBs) are obtained after the proper extrusion process. During following long-term thermal exposure, the solute along HAGBs gradually evolves into nano-precipitates, while the precipitation process along LAGBs is obviously suppressed due to the intrinsically low-energy character, and numerous G. P. zones and γ” phases are formed in deformed regions, which always keep the limited size and reticular distribution. Consequently, the bimodal-grain structure is thermally stable, and the excellent high-temperature strength can be well maintained.