AbstractThis paper presents the results of a study of the effect of interface microstructure and related mechanical properties on the overall mechanical behaviour of an Al alloy metal matrix composite (A356) containing 10 vol.-%SiC particles. Two different interface microstructures were obtained by using as received or oxidised SiC particles. For the oxidised particle composites, TEM observations show a spinel phase (MgAl2O4) formation at the Al/SiC interface, whereas for as received particle composites very few chemical reactions are observed. The particle oxidation reduces the mechanical strength (0·2% proof stress (σ0·2 and ultimate tensile strength (UIS)) and increases ductilityɛfconsiderably. In addition, it is evident from tensile tests carried out in an SEM that these two different types of overall behaviour are a result of different failure processes: particle rupture in the as received particle composites and interface decohesions in the oxidised particle composites.MST/1105