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在原位Mg2Si/Al复合材料中,通过P和混合稀土复合变质及改变半固态等温热处理的保温温度和保温时间,研究了复合变质及等温热处理对合金组织与力学性能的影响。结果表明,P和混合稀土联合变质后初生Mg2Si的形貌由粗大的十字状结构转变为不规则的多边形,均匀分布在铝基体上。初生相颗粒尺寸由未变质前的83μm减小到约17μm;经过570℃×90min半固态等温热处理后,初生Mg2Si相和α-Al相均转变为近球形,初生Mg2Si相形状因子约为0.96,平均等积圆直径约为16μm,此时材料的硬度(HB)达到最大值,为106。
In - situ Mg2Si / Al composites, the effect of composite modification and isothermal heat treatment on the microstructure and mechanical properties of the alloy was investigated by means of composite modification of P and mixed rare earths and changing the soaking temperature and holding time of semi - solid isothermal heat treatment. The results show that the morphology of primary Mg2Si transformed from coarse cruciform structure to irregular polygons and uniformly distributed on the aluminum matrix after the combined modification of P and rare earth elements. The size of the primary phase decreases from 83μm without pre-metamorphism to about 17μm. The primary Mg2Si phase and the α-Al phase both transform to near spherical shape after the semi-solid isothermal heat treatment at 570 ℃ for 90min. The shape factor of primary Mg2Si phase is about 0.96, the average equivalent circle diameter of about 16μm, then the hardness of the material (HB) reached a maximum value of 106.