Ce对半固态A356铝合金初生α相细化机制的新探

摘要

The rare earth Ce was selected as the refiner for A356 alloy,and the alloy melt was isothermally held up and below the eutectic temperature for several minutes before the pouring to research the effect of RE-Al eutectic reaction on the morphology and size of the primary α phase in A356 alloy.The results indicate that the desirable morphology and smaller grain size of primary α phase could be obtained by the isothermal holding of the A356-Ce alloy below the eutectic temperature.By calculating the planar misfit,it was found that the eutectic reaction product Al11Ce3 could be used as the site of the heterogeneous nucleation for α-Al and played the role of grain refinement.%选用稀土Ce作为A356合金的细化剂,合金熔体在浇注前分别在Al-Ce共晶温度上、下保温若干时间,研究稀土-铝共晶反应对A356合金初生α相形貌和晶粒尺寸的影响.试验结果表明:A356-Ce合金在Al-Ce共晶温度之下保温,可获得较理想的初生α相形貌和较小的晶粒尺寸.通过计算二维错配度,发现共晶反应产物Al11Ce3可作为α-Al的异质形核质点而起到细化晶粒的作用.