人工时效对激光选区熔化AlMg4.5Sc0.55Mn0.5Zr0.2合金显微组织和力学性能的影响

采用激光选区熔化制备AlMg_4.5Sc_0.55Mn_0.5Zr_0.2合金，研究人工时效工艺参数对合金维氏硬度的影响规律，分析沉积态和优选时效态合金的室温拉伸性能和显微组织。结果表明：人工时效使该合金的维氏硬度由102HV提升至140HV以上。随着时效温度升高（305~335℃）或时效时间延长（1.5~48 h），维氏硬度呈现先增加、再降低、最后逐渐趋于稳定的规律。在315℃时效3 h或12 h后，合金的室温拉伸性能基本相当，无明显的各向异性；抗拉强度和屈服强度分别达到470 MPa和410 MPa，断后伸长率保持在15.0%。力学性能的提升得益于人工时效过程中弥散析出且与基体共格的纳米增强颗粒Al₃（Sc，Zr）。

Effect of artificial ageing on microstructures and mechanical properties of selective laser melted AlMg4.5Sc0.55Mn0.5Zr0.2 alloy

AlMg_4.5Sc_0.55Mn_0.5Zr_0.2 alloys were fabricated by selective laser melting.The effects of artificial ageing parameters on Vickers hardness of the alloy were investigated.The room temperature tensile properties and microstructures of as-built and optimized artificial ageing treated alloys were analyzed.Results indicate that the Vickers hardness of the alloy increases from 102HV to more than 140HV by artificial ageing treatment.As the rising of ageing temperature,ranging from 305℃to 335℃,or prolongation of the ageing duration,from 1.5 h to 48 h,Vickers hardness presents increasing first,then decreasing and finally trends to be stable.The room temperature tensile properties of the alloys aged at 315℃for 3 h or 12 h are almost equal,and there is no obvious anisotropy.The ultimate tensile strength and yield strength reach 470 MPa and 410 MPa respectively,with elongation of about 15.0%.The improvement of mechanical properties is due to the dispersion precipitation of nano-reinforced particles Al 3(Sc,Zr),which possess a coherent interface with the matrix during artificial ageing.