Abstract: A method of producing a silicon based alloy is described which comprises melting a silicon alloy containing greater than 50 wt. % silicon and preferably including aluminium. The melted alloy is then inert gas atomized to produce powder or a spray formed deposit in which the silicon forms a substantially continuous phase made up of fine, randomly oriented crystals in the microstructure. The alloy produced by the method has particularly useful application in electronics packaging materials and a typical example comprises an alloy of 70 wt. % silicon and 30 wt. % aluminium. Such an alloy is an engineering material which, for example, is machinable.