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利用光学显微镜(OM)、扫描电子显微镜(SEM)、X线衍射分析(XRD)、透射电子显微镜(TEM)、背散射电子衍射分析(EBSD)、显微维氏硬度和拉伸试验等测试方法对预挤压Mg-Gd-Y-Zr合金板热轧后的显微组织和力学性能进行研究。挤压板在热轧过程中发生连续动态再结晶,晶粒尺寸由挤压态的18μm细化至13.5μm,增强细化强化效果。相比于挤压态,轧制态合金的(0002)基面织构增强,强化织构强化效果。同时轧制态合金中Mg5(Gd,Y)动态分解相体积分数有所增加,增强第二相粒子强化效果。在三者的综合强化作用下,较挤压态合金沿挤压方向(ED)的抗拉强度(UTS)为312 MPa、屈服强度(TYS)为213 MPa,轧制态合金沿轧向(RD)的抗拉强度(UTS)和屈服强度(TYS)得以提高,分别为342、264 MPa,伸长率(EL)也由挤压态的6.6%增加至9.5%。轧制态合金经过200℃时效55 h后,合金抗拉强度和屈服强度分别提高至421 MPa和351 MPa,伸长率降低至3.3%。
The samples were characterized by optical microscope (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), backscattered electron diffraction (EBSD), micro Vickers hardness and tensile test The microstructure and mechanical properties of the pre-extruded Mg-Gd-Y-Zr alloy plate after hot rolling were studied. During the hot rolling process, the continuous dynamic recrystallization of the extruded plate occurred. The grain size was refined from 18μm to 13.5μm in the extruded state, enhancing the refinement strengthening effect. Compared with the extruded state, the (0002) base texture of the rolled alloy is strengthened and the texture strengthening effect is strengthened. At the same time, the volume fraction of Mg5 (Gd, Y) dynamic decomposition phase in the as-rolled alloy increases to enhance the strengthening effect of the second phase particles. Under the combined effect of the three, the tensile strength (UTS) of the extruded alloy is 312 MPa and the yield strength (TYS) is 213 MPa along the extrusion direction (ED) ) Increased the tensile strength (UTS) and yield strength (TYS) by 342,264 MPa and elongation (EL) increased from 6.6% to 9.5% in the as-extruded state respectively. After aging at 200 ℃ for 55h, the tensile strength and yield strength of the alloy increased to 421 MPa and 351 MPa, respectively, and the elongation decreased to 3.3%.