Influence of Al-Al2O3 composite powder on the matrix microstructure in composite casts

The structural characterization is presented of composite casts with an AlMg4 alloy matrix, with the composite powder (Al-Al2O3)cp reinforcement obtained in a rotary-vibration mill. On the cross-sections of ingots, metallographic specimens have been made and, by means of quantitative metallographic methods, the grain size distributions have been determined. Statistical tests of the results obtained from the grain plane section area measurements have been performed. An influence has been found of the (Al-Al2O3)cp composite powder on the matrix grain size distribution, depending on the distribution of the composite powder particles in the ingot, whereas no influence of (Al-Al2O3)cp on the mean grain size of the AlMg4 alloy has been found.