铸态和挤压态Mg-4Sm-Al-0.3Mn-xZn合金微观组织和力学性能研究

Microstructures and Mechanical Properties of as-Cast and as-Extruded Mg-4Sm-Al-0.3Mn-xZn Alloys

本工作通过光学显微镜(OM)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、拉伸试验机对铸态和挤压态Mg-4SmAl-0.3Mn-x Zn(x=0、1、2、3)(质量分数)合金的微观组织及力学性能进行了研究。铸态、固溶态合金中观察到了Mg-Al-Sm三元析出相,它是一种长条形基面析出相,具有六方结构,其中a=0.556 nm,c=0.521 nm。该相与镁基体的位向关系为:[0001]_(Mg-Al-Sm)‖[0001]_(α-Mg),■_(Mg-Al-Sm)‖■_(α-Mg)。三种元素的原子比为Mg∶Al∶Sm=98.73∶0.71∶0.56。铸态合金中Mg-4Sm-Al-0.3Mn-3Zn合金具有最佳的拉伸性能,其屈服强度、抗拉强度和延伸率分别为96 MPa、138 MPa和7.2%。挤压态合金中Mg-4Sm-Al-0.3Mn-2Zn合金具有最佳的拉伸性能,其屈服强度、抗拉强度和延伸率分别为269 MPa、298 MPa和16%。

Microstructures and mechanical properties of as-cast and as-extruded Mg-4Sm-Al-0.3Mn-xZn(x=0,1,2,3)(mass fraction)alloys were investigated by optical microscope(OM),X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM)and tensile testing machine.The Mg-Al-Sm ternary precipitated phase were observed in as-cast and solution-treated alloys.It is a precipitation phase with hexagonal structure with a=0.556 nm,c=0.521 nm.The orientation relationship between the phase and the magnesium matrix is[0001]Mg-Al-Sm‖[0001]α-Mg,[1 010]Mg-Al-Sm‖[112 0]α-Mg.The atomic ratio for Mg∶Al∶Sm is 98.73∶0.71∶0.56.The as-cast Mg-4Sm-Al-0.3Mn-3Zn alloy exhibits the best tensile properties with yield strength of 96 Mpa,tensile strength of 138 Mpa and elongation of 7.2%.The as-extruded Mg-4Sm-Al-0.3Mn-2Zn alloy exhibits the best tensile properties.The yield strength,tensile strength and elongation are 269 Mpa,298 Mpa and 16%,respectively.