Microstructure Of The Gravity Cast AlMg10-Graphite Particles Composites
Zbigniew Konopka, Małgorzata Cisowska Politechnika Częstochowska, Wydział Metalurgii i Inżynierii Materiałowej, al. Armii Krajowej 19, 42-200 Częstochowa
Annals 1 No. 1, 2001 pages 86-88
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abstract Fabrication and microstructure of the AlMg10 matrix composite containing 10% volume fraction of graphite particles were presented in this paper. The electrographite particles and chemically refined graphite flakes were used in order to comparison their wetting by liquid metal and arrangement in composite matrix. Composite suspension was manufactured by using mechanical stirring where the propeller mixer was applicated. During stirring process the temperature of liquid metal, time of mixing and rotational speed of mixer were fixed. After stirring process composite suspension was gravity cast into metal mould. Microscopic observations of composite microstructure were carried out. Different arrangements of graphite particles in composite matrix were found. Uniform arrangements of chemically refined graphite flakes in composite matrix were observed in comparison with electrographite particles. In these composite castings any clusters of graphite particles and porosity have been observed. In composites with electrographite particles the graphite clusters are formed and distribution is generally less uniform. Numerous voids were found in spaces between graphite particles in these clusters and good wetting of graphite phase has not been achieved. On the ground of obtained results it can be concluded that chemically refined graphite flakes are better wetted by liquid matrix alloy and very good arrangements of these particles can be achieved.