【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】 Effects of low superheat pouring with a shearing field(LSPSF) on the grain size and morphology of primary Si in hypereutectic Al-20Si alloy have been observed.The results show that semi-solid Al-20Si alloy slurry and billets with excellent quality can be prepared by LSPSF.Primary Si with uniform distribution is converted from plate-like structure into polygonal bulk structure,obtaining obvious refinement.The LSPSF refining effects can be enhanced by P modification,however,the segregation of primary Si phase can be observed with lower pouring temperature.The refinement and spheroidization of primary Si in the Al-20Si alloy is attributed to enhancing heterogeneous nucleation and controlling the anisotropic growth of primary Si phase by LSPSF.更多还原