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制备了3种成分的Mg-Gd-Zn三元合金,并对其显微组织和力学性能进行了较系统的研究.结果表明,Mg-(11-13)Gd-1Zn(质量分数,%)三元合金的铸态组织由α-Mg,(Mg,Zn)_3Gd和具有14H结构的长周期堆垛有序相(14H-LPSO)组成;(Mg,Zn)_3Gd呈现典型的网状共晶形貌,其体积分数随Gd含量的增加而增大.热挤压过程中(Mg,Zn)_3Gd相破碎,其颗粒沿挤压方向排列,而14H-LPSO相则分布于条状分布的(Mg,Zn)_3Gd颗粒之间.铸态和挤压态合金在高温固溶处理后,14H-LPSO相的体积分数增加,大部分(Mg,Zn)_3Gd相溶入基体.挤压态合金经固溶和时效(T6)处理后,显微组织中14H-LPSO相的体积分数大幅度增加,而且出现了β′和β_1沉淀颗粒.对挤压后的合金直接进行时效处理(T5)过程中也形成了β′和β_1沉淀,但14H-LPSO相没有显著增加.3种合金中Mg-11Gd-1Zn合金在T6态的性能最好,抗拉强度高达416 MPa.
Three kinds of Mg-Gd-Zn ternary alloys were prepared and their microstructures and mechanical properties were studied systematically.The results showed that Mg- (11-13) Gd-1Zn (mass fraction,% The as-cast microstructure of the ternary alloy consists of α-Mg, (Mg, Zn) _3Gd and 14H-LPSO with long period stacking structure with 14H structure. (Mg, Zn) _3Gd exhibits typical reticular eutectic (Mg, Zn) 3 Gd phases are broken during the hot extrusion process, and the particles are arranged along the extrusion direction while the 14H-LPSO phase is distributed in the stripe distribution ( Mg, Zn) _3Gd particles.The volume fraction of 14H-LPSO phase increased and most of (Mg, Zn) _3Gd phase dissolved into the matrix after solution treatment at high temperature in as-cast and extruded alloys. The volume fraction of 14H-LPSO phase in the microstructure increased significantly after solution treatment and aging treatment (T6), and the precipitated particles of β ’and β1 appeared.During the aging treatment of the extruded alloy (T5) Β1 and β1 precipitates were also formed, but the 14H-LPSO phase did not increase significantly.The properties of Mg-11Gd-1Zn alloy in the three alloys were the best in the T6 state, and the tensile strength was as high as 416 MPa.