Refining of metal matrix composite melts with exogeneous carbide phases

The ability of cast aluminum matrix composites to recycling by direct remelting is determined by both the opportunity of their processing, while maintaining reinforcing particles to the maximum level, and, if necessary, the opportunity of complete refining of the matrix aluminum alloy from exogenous phases to be used at downstream facilities as a conventional secondary alloy for noncritical mold casting. The paper presents the results of studies on the influence of refining with fluxes and inert gas of melts of aluminum matrix composite materials with exogenous carbide phases (SiC, B4C) on the quality of cast workpieces based on a set of characteristics. It has been shown that to separate SiC reinforcing particles from matrix aluminum-silicon alloys completely, it is recommended to treat melts with a flux composition (18...20% NaCl, 48...50% KCl, 25...27% Na3AlF6, 5...7% Na2CO3) at 750 oC, in an amount of 0.3% by weight of the melt, while achieving a metallurgical yield of 85% of a high-quality secondary alloy or higher. Flux treatment of composite melts containing B4C particles can be recommended for separating the exogenous phase only in a combined option with additional technological methods to increase the separation efficiency. The operation of argon purging can be provided for in the comprehensive processing of melts of secondary metal matrix composites to increase the degree of purification from reinforcing particles in addition to flux refining, which will contribute to increasing the metallurgical yield of the recycled matrix alloy.The research was funded by the grant of the Russian Science Foundation, No. 21-79-10432, https://rscf.ru/project/21-79-10432/.