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采用等通道转角挤压(ECAP)工艺以Bc路径在623K温度下对Mg-1.5Mn-0.3Ce镁合金进行变形,观察显微组织与织构,测试了力学性能。显微组织分析表明,镁合金经ECAP变形晶粒尺寸明显得到细化,经6道次ECAP变形后晶粒尺寸由原轧制态的约26.1μm细化至约1.2μm,且细小的第二相粒子Mg12Ce弥散分布于晶内及晶界处;同时经ECAP变形后,原始轧制织构随变形道次的增加不断减小,并开始转变为ECAP织构,织构强度不断增强;力学性能结果表明,由于晶粒细化作用大于织构软化作用,前3道次ECAP变形镁合金强度随道次的增加不断提高,与Hall?Petch关系相符,在第3道次时其抗拉强度和屈服强度达到最大值,分别为272.2和263.7MPa;在4道次之后形成较强的非基面织构,镁合金强度下降,与Hall?Petch呈相悖关系。断口分析表明,轧制态与ECAP变形镁合金的断裂方式都是沿晶断裂,由于6道次变形镁合金晶粒细化,存在更多的韧窝并获得16.8%最大室温伸长率。
The deformation of the Mg-1.5Mn-0.3Ce magnesium alloy was studied by the ECAP process with Bc at 623K. The microstructure and texture were observed and the mechanical properties were tested. Microstructure analysis shows that the grain size of magnesium alloy is obviously refined by ECAP deformation. After 6 passes of ECAP deformation, the grain size is refined from about 26.1μm to about 1.2μm in the original rolling state, and the fine second The grain size of Mg12Ce dispersed in the grain boundaries and grain boundaries. At the same time, the texture of the original rolled textured steel decreased with the increase of deformation pass through ECAP, and began to transform into ECAP texture. The texture strength increased continuously. The mechanical properties The results show that the intensity of grain refinement is greater than that of texture softening. The strength of ECAP magnesium alloy in the first three passes increases with the increase of pass number, which accords with Hall Petch relationship. At the third pass, the tensile strength and The yield strength reached its maximum at 272.2 and 263.7 MPa, respectively. After 4 passes, a strong non-basal texture was formed and the strength of the magnesium alloy decreased, which was contrary to Hall Petch. Fracture analysis shows that the rupture modes of both rolled and ECAP deformed magnesium alloys are intergranular fracture. Due to the grain refinement of 6-pass deformed magnesium alloy, more dimples exist and the maximum room temperature elongation of 16.8% is obtained.