EFFECTS OF SOLUTES ON GRAIN-REFINEMENT OF SELECTED WROUGHT ALUMINUM-ALLOYS

An analysis of the effects of alloy additions on grain refinement in a series of model and commercial aluminium alloy compositions is report ed. The data of Birch and Fisher published earlier describing grain re finement in 32 systems, including AA3004, AA5083, AA6063, and AA7050, are considered in terms of the supercoding effect of each alloy additi on. A simple model describing grain size in terms of additive supercoo ling effects of individual alloy additions is proposed which fits the data reasonably well. Deviations from simple additive behaviour are ev ident in systems where strong intermetallic interactions occur. Intera ction coefficients among solutes are invoked to explain these deviatio ns. Individual alloying effects on grain refinement are treated in ter ms of constitutional supercooling parameters, and behaviour is shown t o be similar to that described in earlier studies. Zirconium is shown to have a general poisoning effect in a range of alloy compositions. ( C) 1997 The Institute of Materials.