Te、Sb对ZL114A合金T6态微观组织与力学性能的影响

Effect of Te, Sb Addition on the Microstructure and Mechanical Properties of ZL114A Alloy in T6 State

ZL114A合金添加Te、Sb元素完成了硅相变质,采用ICP测定了化学成分,借助DSC、万能试验机、OM、SEM、EDS与TEM测试了不同T6态下合金的力学性能、硅相形貌与组织演化规律。结果表明:随着固溶/时效温度上升,Te、Sb元素固溶数量与密度持续增加,Al4(Te, Sb)共晶相数量不断减少,520～530℃范围内吸热峰峰值连续上升,Si相形貌由针片状、多边形状与长棒状逐渐演变为短棒状、椭圆状与球状,球形平均粒径仅为9μm;Si、Mg元素固溶数量与密度、淬火瞬间Si相过固溶度随之增加。545℃固溶20 h选用聚乙二醇淬火经170℃时效10 h,合金材料平均抗拉强度、屈服强度、延伸率、断面收缩率与维氏硬度高达360MPa、307MPa、10.4%、13.8%与1220MPa,断口表面以韧窝断裂为主,伴生少量沿晶断裂带,Mg2Si强化相平均长度约为224 nm。

The silicon modification was prepared by adding Te and Sb elements in the smelting process.The chemical composition of the material was determined by inductively coupled method,and the mechanical properties,morphology and microstructural evolution of silicon under different T6 states were analyzed by DSC,OM,SEM,EDS,TEM and universal testing machine.The results show that the number and density of Te,Sb and Si,Mg elements dissolve in the primary α-Al matrix and the endothermic peak among from 520℃ to 530℃ increase with the increase of the solid solution and aging temperature,together with an increased solution supersaturation of silicon in the quenching moment.Whereas,the quantity of Al4(Te,Sb)eutectic phase reduces continuously,the morphology of silicon particles changes from pin-like,polygonal and long-rod to short-rod-like,oval and spherical,and the average size is merely 9μm.The average tensile strength,yield strength,elongation,reduction of area and Vickers hardness after solidificating at 545℃ for 20h and aging at 170℃ for 10h with the polyethylene glycol quenching medium are 360MPa,307MPa,10.4%,13.8%and 1220MPa,respectively.The dimple morphology is the dominated fracture surface,accompanied by some intergranular fracture zone,and the average length of Mg2Si phase is about 224nm.