【摘要】 研究了剪切低温浇注式半固态浆料制备工艺(LSPSF)对Al-20Si过共晶合金中初生Si相尺寸和形貌的影响。结果表明,LSPSF工艺可制备质量优良的Al-20Si合金半固态浆料和坯料;初生Si得到明显细化,分布均匀,形态发生了明显改变,由板片状转变为多角块状;磷变质处理可强化LSPSF工艺的细化效果,但浇注温度过低时,初生Si相发生偏聚。在LSPSF工艺条件下,初生Si得以细化和圆整化主要归因于LSPSF工艺引起的增强异质形核作用和抑制初生Si择优生长作用。更多还原

【Abstract】 Hypereutectic Al-20%Si alloy was rheocast by a novel process,termed low superheat pouring with a shear field(LSPSF).The primary silicon phases are fined greatly and distributed homogeneously,and most of them are in polygonal or round type when the Al-20%Si alloy was rheocast by LSPSF process.The grain refining effect of LSPST process can be enhanced by the modification of phosphorus,however the segregation of primary silicon crystals will happen when Al-20%Si alloy is rheocast at a critical pouring temperature.The main reason for the grain refinement and morphology improvement of primary silicon crystals should be contributed to the enhanced heterogeneous nucleation and limited anisotropic growth of primary silicon.更多还原