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采用真空感应熔炼与阶梯型铜模喷铸相结合,制备出添加SiC颗粒增强亚快速凝固镁合金试样。通过等温固溶处理,定量分析了冷速及细化剂含量共同影响下镁合金晶粒尺寸变化的规律,并对相关细化机理进行了讨论。结果表明,铜模喷铸镁合金快冷组织主要由细小粒状晶组成,经400℃×2h固溶处理后转变为多边形等轴晶组织。随铜模内径降低,凝固冷速提高,有效形核分数的增大导致镁合金晶粒尺寸下降,分布趋于均匀。当添加2%的SiC时,4mm铜模内径对应的镁合金晶粒尺寸可细化到4μm,并形成整体细晶组织。
Using vacuum induction melting and ladder-type copper mold spray combination, prepared by adding SiC particles enhanced sub-rapid solidification magnesium alloy sample. By isothermal solution treatment, the regularity of grain size change of magnesium alloy was quantitatively analyzed under the influence of cooling rate and refiner content, and the relevant refining mechanism was discussed. The results show that the rapid cooling microstructure of the copper alloy die-cast magnesium alloy is mainly composed of fine granular crystals, and transformed to polygonal equiaxed microstructure after solution treatment at 400 ℃ for 2h. With the decrease of the inner diameter of the copper mold, the solidification cooling rate is increased, and the increase of the effective nucleation fraction leads to the decrease of the grain size and the distribution of the magnesium alloy. When 2% SiC is added, the grain size of magnesium alloy corresponding to 4mm copper mold inner diameter can be refined to 4μm, and the whole fine grain structure can be formed.