Effects of P+Cr complex modification and solidification conditions on microstmcture of hypereutectic Al-Si alloys by wedge-shaped copper mould casting  

作　　者：Zhang Haitao Zuo Kesheng Han Xing Shao Bo Qin Ke Cui Jianzhong 

机构地区：[1]Key Lab of Electromagnetic Processing of Materials, Ministry of Education, Northeastern University

出　　处：《China Foundry》2014年第6期481-486,共6页中国铸造（英文版）

基　　金：financially supported by the National Basic Research Program of China(Grant No.:2012CB723307-03);the Fundamental Research Funds for the Central Universities(Grant No.:N130409003);the National Natural Science Foundation of China(Grant No.:51204046)of China

摘　　要：Large and segregated primary Si particles may drastically decrease the mechanical properties of AI-Si alloys. To solve this problem, a P-Cr complex modifier was added into the alloy, and the effects of P-Cr complex modification and solidification conditions on the microstructure of hypereutectic Al-Si alloys casting produced in wedge-shaped copper mould were studied. The thermal analysis technique was applied to calculate the cooling rate during solidification. The microstructures were observed by means of optical and scanning electron microscopies. Results showed that the primary Si segregates in the as-cast hypereutectic AI-Si alloys. The segregation of primary Si can be inhibited by adding a P＋Cr complex modifier and increasing the cooling rate during solidification. The refinement of primary Si particles by P＋Cr complex modification is due to the formation of CrSi2 and AlP particles which act as the heterogeneous nuclei for the primary Si phase. The segregation of Si was also inhibited through the adherence of heavier CrSi2 particles to the primary Si particles.Large and segregated primary Si particles may drastically decrease the mechanical properties of Al-Si alloys. To solve this problem, a P-Cr complex modif ier was added into the alloy, and the effects of P-Cr complex modification and solidification conditions on the microstructure of hypereutectic Al-Si alloys casting produced in wedge-shaped copper mould were studied. The thermal analysis technique was applied to calculate the cooling rate during solidification. The microstructures were observed by means of optical and scanning electron microscopies. Results showed that the primary Si segregates in the as-cast hypereutectic Al-Si alloys. The segregation of primary Si can be inhibited by adding a P+Cr complex modif ier and increasing the cooling rate during solidif ication. The ref inement of primary Si particles by P+Cr complex modif ication is due to the formation of CrS i2 and AlP particles which act as the heterogeneous nuclei for the primary Si phase. The segregation of Si was also inhibited through the adherence of heavier CrS i2 particles to the primary Si particles.

关 键 词：hypereutectic Al-Si alloys primary silicon P-Cr complex modifier cooling rate 

分 类 号：TG146.12[一般工业技术—材料科学与工程]