1997 Volume 38 Issue 7 Pages 622-629
An investigation was made on the rheorefining process of Al–Sn and Al–Ni alloys in order to reproduce efficiently high-purity metallic materials. The load applied to the Al–Ni and Al–Sn alloy ingots during rheorefining increased rapidly and subsequently changed with repeating of its alternate increase and decrease like a sawtooth. The height of the ingot during the rheorefining reduced with increasing load and reduced slightly with decreasing load. The chemical composition of an initial composition Al-50%Sn alloy ingot rheorefined by pressurizing the ingot for 72 ks at a plunger speed of 2.8×10−4 mm/s was 98% Al and less than 0.01% Sn. Thus, a large amount of tin could be almost completely removed from the alloy ingot, although a small amount of eutectic was formed by chemical reaction with the steel filter. In the rheorefining by pressurizing Al–Ni alloy ingots for 72 ks at a plunger speed of 2.8×10−4 mm/s, the nickel in the alloy ingots with initial compositions of Al-2%Ni, Al-1%Ni, Al-0.5%Ni and Al-0.2%Ni was also removed effectively. It was known in the rheorefined Al–Ni alloy ingot with the initial content of 0.5%Ni that the amount of exuded filtrate increased and the nickel content decreased with an increase in isothermal rheorefining temperature. It was observed in the microstructure of the rheorefined Al–Ni alloys having initial contents of 0.2 to 2 mass%Ni that the fraction of eutectic decreased with a decrease in initial nickel content of the alloy ingots. It was found that the slow rheorefining for 72 ks at a plunger speed of 2.8×10−4 mm/s was superior to the fast rheorefining for 7.2 ks at a plunger speed of 2.8×10−3 mm/s in order to remove impurities from the Al–Sn alloy ingot.
