Achieving high strength-ductility synergy in a Mg97Y1Zn1Ho1 alloy via a nano-spaced long-period stacking-ordered phase
Mingyu Fan, Ye Cui, Yang Zhang, Xinghao Wei, Xue Cao, Peter K. Liaw, Yuansheng Yang, Zhongwu Zhang
Abstract
Achieving high strength in Mg alloys is usually accompanied by ductility loss. Here, a novel Mg97Y1Zn1Ho1 at. % alloy with a yield strength of 403 MPa and an elongation of 10% is developed. The strength-ductility synergy is obtained by a comprehensive strategy, including a lamella bimodal microstructure design and the introduction of nano-spaced solute-segregated 14H long-period stacking-ordered phase (14H LPSO phase) through rare-earth Ho alloying. The lamella bimodal microstructure consists of elongated un-recrystallized (un-DRXed) coarse grains and fine dynamically-recrystallized grains (DRXed regions). The nano-spaced solute-segregated 14H LPSO phase is distributed in DRXed regions. The outstanding yield strength is mainly contributed by grain-boundary strengthening, 18R LPSO strengthening, and fiber-like reinforcement strengthening from the nano-spaced 14H LPSO phase. The high elongation is due primarily to the combined effects of the bimodal and lamellar microstructures through enhancing the work-hardening capability.