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

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

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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 for γ-Mg17Al12 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-sized γ-Mg17Al12 continuous precipitates was produced in as-extruded AlN/AZ91 composites af-ter peak-aging.During tension,gliding dislocations bypassed spherical γ-Mg17Al12 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-shearable γ-Mg17Al12 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 pyramidal<c+a>slip 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.

Magnesium matrix compositesMechanical propertiesPrecipitationDeformation mechanismsNon-basal slip

Bin Zhang、Yunxia Sun、Tuo Liang、Yunzhen Li、Tian Li、Jingchao Wang、Ruiru Cai、Changlin Yang

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State Key Laboratory of Solidification Processing,Northwestern Polytechnical University,Xi'an 710072,China

National Natural Science Foundation of ChinaNational Natural Science Foundation of ChinaKey R&D Project of Shaanxi ProvinceResearch Fund of the State Key Laboratory of Solidification Processing(NPU),China

52071268517711512022GY-3662022-BJ-04

2024

10.1016/j.jmst.2023.06.039

材料科学技术(英文版)
中国金属学会 中国材料研究学会 中国科学院金属研究所

材料科学技术(英文版)

CSTPCD
影响因子：0.657
ISSN：1005-0302
年,卷(期)：2024.172(5)
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