Aluminium alloy treatment.

摘要

A method of removing unwanted inclusion particles from a body of liquid aluminium or aluminium alloy by deposition thereof comprising 1. (a) adding to the liquid metal at least one alloying constituent in greater quantity than is eventually required and (b) raising the metal temperature higher than the desired casting temperature and above that liquidus of the alloy below which some intermetallic particles can form, 2. causing the temperature of the liquid metal to fall below the said liquidus so that intermetallic phase particles nucleate and cause the residual liquid metal to alter its composition and temperature according to the liquidus line of the phase diagram until it achieves a desired temperature and composition, characterised in that:- the alloying constituent is chosen so as to form a peritectic system with aluminium and the intermetallic is chosen to nucleate preferentially on or in the vicinity of certain inclusion particles and grow to form complex bodies which have an enhanced settling rate and which grow to a size and with a morphology such that during settling the liquid metal is scavenged of other smaller particles.