Troisiéme Conférence Européenne sur les Matériaux et les Procédés Avancés
J. Phys. IV France 03 (1993) C7-1837-C7-1843
The role of rare earths additions to aluminium-matrix compositesP. MOLDOVAN1, C. ALEXANDRU1, G. POPESCU1, D. CONDEIU1 and G.V. GHICA2
1 Faculty of Materials Science and Engineering, University Politechnica, Splaiul Independentei 313, Bucharest 77206, Romania
2 I.N.T.E.C.-S.A. Bucharest, Romania
Aluminium alloy (Al-5 wt.% Mg) matrix composites with ceramic particles (SiCp) as dispersoids and additions of 1-1.5 wt .% mischmetal (55 % Ce ; 20 % La ; 15 % Nd ; 6.5 % Pr ; .36 % Fe ; bal.others) have been synthesised by liquid metallurgy. During preparation of the composites a reacted layer which contains rare earths (La, Dy, Tb) has been found to form at the matrix / ceramic particles interface. The thikness of reaction layer can be controlled by vortex technique. The rare earth additions can play similar role like Mg for improving the wetting between the matrix and the surface of dispersoids. The rare earth oxides can form spinels with other oxides. La and Ce can form intermetallic compounds with Al (LaAl4, CeAl4) with changes the chemical activity and viscosity of the melt thereby minimising the agglomeration of ceramic particles and improving the dispersion of SIC particles in cast composite.
© EDP Sciences 1993