摘要
Grain boundary strengthening is an effective strategy for increasing mechanical properties of Mg alloys.However,this method offers limited strengthening in bimodal grain-structured Mg alloys due to the difficultly in increasing the volume fraction of fine grains while keeping a small grain size.Herein,we show that the volume fraction of fine grains(FGs,~2.5μm)in the bimodal grain structure can be tailored from~30 vol.%in Mg-9 Al-1 Zn(AZ91)to~52 vol.%in AZ91-1Y(wt.%)processed by hard plate rolling(HPR).Moreover,a superior combination of a high ultimate tensile strength(~405 MPa)and decent uniform elongation(~9%)is achieved in present AZ91-1Y alloy.It reveals that a desired bimodal grain structure can be tailored by the co-regulating effect from coarse Al_(2)Y particles resulting in inhomogeneous recrystallization,and dispersed submicron Mg_(17)Al_(12)particles depressing the growth of recrystallized grains.The findings offer a valuable insight in tailoring bimodal grain-structured Mg alloys for optimized strength and ductility.
基金
primarily supported by The Natural Science Foundation of China under Grant Nos.51922048,51871108,51625402 and 51671093
Partial financial support came from the Fundamental Research Funds for the Central Universities,JLU,Program for JLU Science and Technology Innovative Research Team(JLUSTIRT,2017TD-09)
The Changjiang Scholars Program(T2017035)。
