The mechanisms of multimodal microstructure evolution and the effects of microstructural factors on mechanical properties must be elucidated to design new alloys with superior properties. In this study, high-fracture-toughness and ductile Mg_96.75Zn_0.85Y_2.05Al_0.35 alloys were developed using rapidly solidified (RS) ribbon-consolidation technique, and the inherited multimodal microstructure evolution during plastic flow consolidation of the RS ribbons was investigated. The use of extrusion for plastic flow consolidation of the heat-treated RS ribbons produced a multimodal microstructure consisting of the worked grains with high Kernel average misorientation (KAM) angles (Group 1), the ultrafine dynamically recrystallized (DRXed) grains with intermediate KAM angles (Group 2), and the fine DRXed grains with low KAM angles (Group 3). Groups 1 and 2 contribute to the alloy strengthening, while Group 3 contributes to improving ductility with strain-hardening, resulting in enhancement of the fracture toughness. To form the multimodal microstructure, it was necessary to apply plastic flow with equivalent strains of >2.3 to the heat-treated RS ribbons possessing duplex microstructures with different dispersions of the long-period stacking ordered phase.

必须阐明多模态微观结构演变的机制和微观结构因素对力学性能的影响，以设计具有优异性能的新合金。在本研究中，高断裂韧性和韧性 Mg _96.75 Zn _0.85 Y _2.05 Al _0.35合金是使用快速凝固 (RS) 带状固结技术开发的，并研究了 RS 带状塑性流动固结过程中继承的多峰微观结构演变。使用挤压对热处理的 RS 带进行塑性流动固结产生了多峰微观结构，包括具有高内核平均取向错误 (KAM) 角（第 1 组）的加工晶粒、具有中间 KAM 角的超细动态再结晶 (DRXed) 晶粒（第 2 组）和具有低 KAM 角的细 DRX 晶粒（第 3 组）。第 1 组和第 2 组有助于合金强化，而第 3 组有助于通过应变硬化提高延展性，从而提高断裂韧性。为了形成多峰微结构，