Sn对时效态ZM61镁合金高温力学性能的影响

利用金相显微镜(OM)、X射线衍射(XRD)、扫描电镜(SEM)和高温拉伸对时效态ZM61-xSn(x=0,6,8,10,质量分数/%,下同)合金的高温拉伸性能及断裂机制进行了研究。结果表明:ZM61-xSn(x=6,8,10)合金的物相由α-Mg,α-Mn,MgZn2,Mg2Sn相组成。添加Sn元素可有效细化ZM61合金组织,提高合金高温强度,但降低合金塑性。ZM61-xSn(x=6,8,10)合金在300℃下拉伸的抗拉强度分别为149,140,145MPa,较相同温度下拉伸的ZM61合金的抗拉强度分别提高了26%,17%,23%。ZM61-xSn(x=0,6,8,10)合金在300℃下拉伸的伸长率分别为39.95%,5.65%,7.01%和6.33%。拉伸温度对ZM61-xSn(x=6,8,10)合金的断裂机制产生显著影响。当拉伸温度低于220℃,合金为穿晶断裂;高于220℃时,合金变为沿晶断裂。

Effects of Sn on Elevated-temperature M echanical Properties of As-aged ZM61 Alloy

The elevated temperature mechanical properties and fracture mechanisms of as‐aged ZM61‐xSn(x=0 ,6 ,8 ,10 ,mass fraction/% )alloys are investigated by optical microscope (OM ) ,X‐ray dif‐fraction(XRD) ,scanning electron microscope (SEM ) and high temperature tensile test .The results show that the phase compositions of ZM61‐xSn(x=6 ,8 ,10)alloys areα‐Mg ,α‐Mn ,MgZn2 and Mg2Sn phases .The Sn element can refine the microstructure ,improve the high temperature tensile strength , but deteriorate the elongation of ZM61 alloy .The ultimate tensile strength of ZM61‐xSn(x=6 ,8 ,10) alloys with tensile test at 300℃are 149 ,140 ,145MPa ,compared with ZM61 alloy which is carried out tensile test at the same temperature ,the tensile strength increased 26% ,17% and 23% ,respectively . The elongation of ZM61‐xSn(x= 0 ,6 ,8 ,10)alloys with tensile test at 300℃ are 39 .95% ,5 .65% , 7 .01% and 6 .33% .The tensile temperature exerts dominating effect for ZM 61‐xSn(x=6 ,8 ,10)al‐loys on the fracture mechanism .As tensile temperature lower than 220℃ ,the alloys show transgran‐ular fracture characteristics .The alloys show intergranular fracture characteristics when the tensile temperature is higher than 220℃ .