The effect of ball milling on the microstructure of powder metallurgy aluminium matrix composites reinforced with MoSi2 intermetallic particles

Six hot extruded Al–Mg–Si composites reinforced with 15 vol.% of MoSi2 intermetallic particles were processed by powder metallurgy, varying reinforcement size and high energy ball milling time. The relation between these parameters and matrix microstructure, final reinforcement size and particle distribution has been investigated. Reinforcement distribution was quantified through the coefficient of variation of the mean near-neighbour distance, COV(λm), which demonstrated to be the most sensitive method to characterize this feature. The results show that by increasing milling time homogeneity of MoSi2 distribution significantly increased, achieving a COV(λm) = 0.41, independently of initial reinforcement size. Increasing milling time, the submicrometric matrix grains and reinforcing particles together with the homogeneous reinforcement distribution gave rise to higher tensile properties without loss of ductility.