FORMATION OF INTERMETALLIC PHASES IN Al-Sc ALLOYS PREPARED BY MOLTEN SALT ELECTROLYSIS AT ELEVATED TEMPERATURES

摘要

Molten salts electrolysis method to prepare Al-RE alloys has attracted increasing attention recently. CaCl_2 and Na_3AlF_6 were the most often used melts for this purpose. In this work, Al-Sc alloys prepared by electrolytic deposition process in both CaCl_2 and Na_3AlF_6 melts were investigated, respectively. It was found that Sc distributes almost uniformly and Sc contents increase with increasing current intensity in both melts. Current efficiency was measured for comparison among various current densities applied. The alloy products were analyzed using XRD and SEM, where the formation behaviors of Al-Sc intermetallics were investigated in details. The experimental and theoretical results demonstrate that Al_3Sc and Al_(0.968)Sc_(0.032) are the major precipitates in the Al-Sc alloys prepared by molten electrolysis. The results are useful for selection and optimization of the molten salts compositions and the parameters of electrolysis operation.