Fabrication of in situ aluminium matrix composite by change in addition sequence of MnO 2 particles

Abstract

In-situ composite of commercially pure aluminium (CPA) matrix and 1 to 4 wt% MnO 2 reinforcement particles were fabricated using stir casting method. 3 wt% Mg was added to improve the wettability of generated in situ phases in CPA matrix. MnO 2 additions were carried out in two sequences named as A and B. In sequence A, MnO 2 was added after melting of CPA with 3 wt% Mg while in sequence B, MnO 2 added before melting of CPA with 3 wt% Mg. The sequence of addition of MnO 2 has been studied in terms of recovery of Mn, mechanical properties and microstructures of fabricated composite. Maximum recovery of Mn obtained in case of sequence B. Improved results in microstructure and mechanical properties were found in sequence B compared to sequence A. Formation of in situ phases such as MnAl 6, MgSiO 3, Al 2 O 3, cemented carbide Mn 3 AlC and small quantity of MgFeSiO 3, were confirmed by Xy diffraction analysis in final composite materials.