Simultaneously enhancing the strength and ductility of as-extruded AlN/AZ91 composites via nano-precipitation and pyramidal slip  

作　　者：Bin Zhang Yunxia Sun Tuo Liang Yunzhen Li Tian Li Jingchao Wang Ruiru Cai Changlin Yang 

机构地区：[1]State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi’an 710072,China

出　　处：《Journal of Materials Science & Technology》2024年第5期240-254,共15页材料科学技术（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.52071268 and 51771151);the Key R&D Project of Shaanxi Province(No.2022GY-366);the Re-search Fund of the State Key Laboratory of Solidification Processing(NPU),China(No.2022-BJ-04).

摘　　要：Age hardening is often used to optimize the mechanical properties of as-deformed Mg-based materials in industry,whereas the improvement of strength is usually accompanied by the significant loss of ductility,which hinders the application of Mg-based materials in structural components.In the present work,high strength-ductility synergy(the yield strength of 263±9 MPa,ultimate tensile strength of 398±7 MPa and elongation to fracture of 34%±1%)was realized in as-extruded AlN/AZ91 composites after optimiz-ing aging processes.Microstructural characterization shows that AlN particles induced a large number of geometrically necessary dislocations around the AlN/Mg interface during extrusion,which decreased the nucleation barrier and provided more heterogeneous nucleation sites forγ-Mg 17 Al 12 continuous precipi-tation.Meanwhile,95%of residual dislocations in as-extruded AlN/AZ91 composites were annihilated dur-ing peak-aging,suppressing the growth and coarsening of continuous precipitates.Therefore,high density of nano-sizedγ-Mg 17 Al 12 continuous precipitates was produced in as-extruded AlN/AZ91 composites af-ter peak-aging.During tension,gliding dislocations bypassed sphericalγ-Mg 17 Al 12 nano-precipitates by Orowan looping rather than cutting mechanism,which induced a strong block on dislocation motion.So high yield strength was mainly attributed to the high density of non-shearableγ-Mg 17 Al 12 nano-precipitates with spherical morphology,which was different from other Mg-Al-based systems.The results of texture evolution and slip trace analysis demonstrated that the suppression of extension twinning and less basal slip was due to the enhanced activity of pyramidalc+aslip in as-extruded AlN/AZ91 com-posites after peak-aging during the room temperature tension,meanwhile,the dislocation density of as-extruded AlN/AZ91 composites was significantly decreased during peak-aging,then higher elongation to fracture was achieved.

关 键 词：Magnesium matrix composites Mechanical properties Precipitation Deformation mechanisms Non-basal slip 

分 类 号：TG1[金属学及工艺—金属学]