挤压态Mg-Sm-Ca合金的显微组织和力学性能（英文）

Microstructure and Mechanical Properties of Extruded Mg-Sm-Ca Alloys

研究了挤压Mg-4.0Sm-xCa(x=0.5,1.0,1.5,mass fraction%)合金经过200℃等温时效处理后的显微组织、时效硬化行为和力学性能。结果表明,随着Ca的添加,在镁基体中形成针/棒状的Mg2Ca相、块状和颗粒状含Ca元素的Mg_(41)Sm_5相,合金的晶粒被细化、拉伸力学性能得到显著提高。在T5(峰值时效)态下,Mg-4.0Sm-1.0Ca合金具有最细的晶粒,其大小约为5.1μm。随着Ca含量的增加,针/棒状的Mg_2Ca相逐渐增多,当Ca含量达到1.5%时,晶界处含Ca的块状Mg_(41)Sm_5相的量明显减少。在峰值时效态下,Mg-4.0Sm-1.0Ca合金具有最大的HV硬度值(820 MPa)以及最佳的力学性能,其抗拉强度、屈服强度和延伸率分别达到了267 MPa,189 MPa和24%。合金力学性能的提高主要归因于晶粒细化、固溶强化以及Mg2Ca相和Mg_(41)Sm_5相的析出强化。

Microstructure,age hardening response and mechanical properties of Mg-4.0Sm-xCa（x=0.5,1.0,1.5,wt%） alloys extruded followed by isothermal aging at 200 ℃ were investigated.The results indicate that with the addition of Ca,the bulk and particle-like Mg（41）Sm5 phase containing Ca and the needle/rod-like Mg2Ca phase are formed in the Mg matrix,grains of the alloy are refined and tensile mechanical properties are improved remarkably.Under T5（peak-aging） condition,the Mg-4.0Sm-1.0Ca alloy shows the smallest grain size of 5.1 μm.With the increase of Ca content the amount of Mg2Ca phase increases gradually,but that of the bulk Ca-containing Mg（41）Sm5 phase,which is mainly distributed at the grain boundaries,decreases obviously when Ca content reaches 1.5 wt%.The peak-aged Mg-4.0Sm-1.0Ca alloy exhibits the highest hardness HV（820 MPa） and the optimal ultimate tensile strength,yield tensile strength and elongation of 267 MPa,189 MPa and 24%,respectively.The improved mechanical properties of the alloy are attributed to the grain refinement,the solution strengthening and the precipitation strengthening of Mg2Ca phase and Mg（41）Sm5 phase.