【摘要】 采用常规铸造和热形变相结合的工艺制备Mg-6Gd-6Y-1Zn四元镁合金,并对其显微组织和力学性能进行较系统的研究。结果表明:合金的铸态组织主要由α-Mg,Mg24(GdYZn)5和具有18R-LPSO结构的Mg12Y1Zn1相组成。合金热挤压过程中Mg12Y1Zn1相被拉长,呈长条状沿挤压方向排列,而14H-LPSO相则分布于Mg12Y1Zn1相之间。挤压态合金在高温固溶处理后,Mg12Y1Zn1相溶入基体,而基体中的14H-LPSO相增加。挤压态合金经固溶和时效(T6)处理后,显微组织中呈现18R-LPSO,14H-LPSO结构和β′沉淀颗粒共存。对挤压后的合金直接进行时效(T5)处理过程中也发生了β′沉淀,但14H-LPSO相体积分数没有T6态多。合金在T6态的性能最好,强度和塑性达到了良好的匹配。更多还原

【Abstract】 A quaternary alloy with composition of Mg-6Gd-6Y-1Zn(mass fraction/%) was prepared by conventional casting and extrusion.The microstructure and aging behavior of the alloy were investigated.The results showed that the as-cast microstructure of the alloy consisted of the α-Mg matrix,Mg24(GdYZn)5 eutectic and Mg12Y1Zn1 phase.After extrusion the Mg12Y1Zn1 phase were stretched along the direction of extrusion,and the 14H-LPSO phase distributed between Mg12Y1Zn1 strips.Solid solution treatment at high temperature above 500℃ resulted in the dissolution of Mg12Y1Zn1 phase into the matrix and increase of the 14H-LPSO phase.When solution treated alloys was aged at temperature of 225℃(T6 treatment),the 14H-LPSO phase and β′ precipitated appear in microstructure.Aging of as extruded alloys(T5 treatment) also caused the formation of β′ precipitates,however the volume fraction of 14H-LPSO phase was lower than that in specimens after T6 treatment.High tensile strength combined with good ductility was obtained from the alloy after T6-aging.更多还原