Abstract

Liquid Cu-Ni-Al alloys and two Li2O-Al2O3-SiO2 liquid slags were contacted for 1-8 min at 1300 and 1450 °C. Their interface was deformed by the formation of a lithium aluminate crust due to aluminum oxidation. The interfacial area evolved with time depending on the compositions of the liquids. This led to the formation of structures made of liquid metal sheathed by a solid lithium aluminate layer. These structures were studied from metallographic sections of quenched samples and from X-Ray radiographs in real time. Their formation was attributed to the semi-permeability of the lithium aluminate layer allowing the transfer of aluminum ions to the slag but impeding the reduced silicon from reaching the liquid metal. Indeed, at the end of the slag-metal reaction, the silicon produced by the reduction of silica by aluminum was not found in the Cu-Ni alloy but silicon-rich droplets were found on the slag side of the crust. An explanation of these phenomena is presented.