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以AZ91D镁合金屑料为原料,采用热压制工艺和半固态等温处理制备半固态坯料,通过显微组织观察和定量金相分析研究了半固态组织均匀性及组织演变。结果表明,在热压制工艺参数下,压坯密度为1.76g/cm3,相对密度可达98%,晶粒得到显著的细化,组织均匀分布。经半固态等温处理后,组织中平均颗粒尺寸为98.6μm,平均颗粒形状因子为1.6,半固态组织分布均匀。半固态组织演变分为3个阶段:Mg17Al12相的溶解,高溶质区域的熔化,固相颗粒的球化和长大。
Semi-solid billets were prepared by hot pressing and semi-solid isothermal treatment using AZ91D magnesium alloy chip as raw material. The microstructure and quantitative metallographic analysis were used to study the microstructure homogeneity and microstructure evolution. The results showed that the density of the green compact was 1.76g / cm3 and the relative density was 98% under the hot pressing parameters. The grains were remarkably refined and the microstructure was evenly distributed. After the semi-solid isothermal treatment, the average particle size in the tissue was 98.6μm, the average particle shape factor was 1.6, and the semi-solid tissue was evenly distributed. Semi-solid microstructure evolution is divided into three stages: dissolution of Mg17Al12 phase, melting of high solute regions, spheroidization and growth of solid-phase particles.