Investigation on Al2O3-Reinforced Zinc-Aluminum Matrix Composites

Abstract

Composite materials obtained by adding particles to the metallic matrix (MMCs) have made remarkable progress in its development and applications in automotive and aerospace industries in recent decades. Among them the most current application is MMCs with zinc and aluminum matrix. The present work is focused on the study of the effect of the directional heat extraction on the alumina distribution inside the zinc-aluminum matrix and on the columnar – to – equiaxed (CET) phenomenon in samples directionally solidified. The ZA-27 alloy was reinforced with ceramic-particulates of alumina (Al₂O₃) and then vertically directionally solidified. The following parameters were measured: cooling rates, temperature gradients, interphase velocities. And the influence of heat transfer on the solidification microstructure of the MMCs was analyzed. Experimental results include transient metal/mould heat transfer coefficients, secondary dendrite arm spacings and particle distribution as a function of solidification conditions imposed by the metal/mould system. The results about the conditions for the CET in MMCs are compared with those obtained in directional solidification of Zn-Al alloys.