Peritectic reaction on the Al-rich side of Al-Cr system

A long lasting controversy on the nature of the reaction between liquid, Al and Al45Cr7 has been ended by planar front solidification experiments of Al-Cr alloy in a Bridgman furnace. Cr depletion in the liquid ahead of the quenched planar interface proves without any ambiguity that the invariant reaction on the Al-rich side of the Al-Cr phase diagram is peritectic. A value of the diffusion coefficient of Cr in liquid Al, Dℓ=2.4×10-9m2/s, was also deduced from the solute composition profile measured in the quenched liquid.