Two kinds of castings manufactured under vacuum pouring and pressure solidification were compared to study the effect of the oxide bifilm on the dispersed shrinkage formation of ZL101A alloy by plaster mold precision casting. The results show that amounts of the bifilm defects introduced in the mold cavity play a significant effect on dispersed shrinkage formation in the plaster mold casting. When more amounts of the bifilm defects and inclusions are introduced into the plaster mold, the sides of the bifilm defects are unbonded and can capture a portion of local inclusions and gas, which eventually increases the tendency to form the aggregation of dispersed shrinkage at the hot spot or in the key places of the casting. When less amounts of the bifilm defects and inclusions are introduced into plaster mold, the dispersed shrinkages distribute more scatteredly.%通过石膏型真空浇注加压凝固两种不同浇注系统的铝合金试样,研究了双膜缺陷对ZL101A合金石膏型精铸缩松缺陷的影响.结果表明,流入型腔中的双膜数量对铝合金石膏型精铸缩松的形成极为关键.流入型腔中的夹杂和双膜数量多,双膜两侧打开后很容易捕获局部夹杂及气体,最终增加了铸件在热节或关键部位形成集中缩松的倾向;流入型腔中的夹杂和双膜数量少,缩松更趋于分散分布.
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