Authors: Liyuan Sun Zhi Wang Hang Chen Dong Wang Guoyu Qian
Publish Date: 2016/11/02
Volume: 48, Issue: 1, Pages: 420-428
Abstract
To fully understand the role of CaAl2Si2 phase in concentrating the nonmetallic impurity phosphorus an experiment of directional solidification of Al70 at pct Si alloy with extreme small lowering rate 005 mm min−1 was carried out With good dynamic condition for the diffusion of impurity Ca Al P from silicon to the S/L interface the CaAl2Si2 phase with 0607 at pct P was successfully observed by Electron Probe Micro Analyzer EPMA and its distribution character was originally presented This impurity phase was widely detected in the refined sample but only at the interface of silicon crystal and AlSi alloy which contributed to the deep removal of impurity P The formation mechanism of CaAl2Si2P phase was thus explored in which the microsegregation and concentration of element P Ca Al in front of S/L interface were crucial After acid leaching the P content decreased from the original 23 ppm to below 5 ppm Compared with normal solidification a 16 pct higher removal efficiency of P was obtained in this study
Keywords: