摘要
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 ternary alloys with composition of Mg-（11—13）Gd-lZn（mass fraction,%） have been prepared and their microstructures and mechanical properties have been also investigated.The results showed that the as cast microstructure of the three alloys consists ofα-Mg matrix,（Mg,Zn）_3Gd eutectic and a 14H long-period stacking ordered（14H-LPSO） phase.With the increase of Gd content the volume fraction of the（Mg,Zn）_3Gd eutectic increases.After extrusion the（Mg,Zn）_3Gd eutectic networks are destroyed and its broken particles are arranged in strips along the direction of extrusion, and the 14H-LPSO phase is distributed between（Mg,Zn）_3Gd strips.Solid solution treatment at high temperature above 500℃results in the dissolution of（Mg,Zn）_3Gd phase into the matrix and the increase of the 14H-LPSO phase.After solution treated alloys are aged at temperature of 225℃（T6 treatment） the volume fraction of the 14H-LPSO phase is further increased and both′βandβ_1 precipitates appear in the microstructure.Aging of as extruded alloys（T5 treatment） also causes the formation ofβ′andβ_1 precipitates but the volume fraction of the 14H-LPSO phase in the T5 treated specimens is lower than that in specimens after T6 treatment.High tensile strength combined with good ductility is obtained from the Mg-11Gd-1Zn alloy after T6 aging.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2012年第6期733-738,共6页
Acta Metallurgica Sinica
基金
江苏省自然科学基金资助项目BK2010392~~
关键词
镁合金
GD
ZN
时效
长周期堆垛有序相
magnesium alloy
Gd
Zn
aging
long-period stacking ordered phase
