AI(Mg)-Ti02/Mo03 BASED IN-SITU COMPOSITES - SYNTHESIS, TENSILE AND TRIBOLOGICAL PROPERTIES

Abstract

The quest for improved performance leads to continuing search for new materials and combinations. Development of aluminium based in-situ composites by dispersing in molten aluminium such oxides, which could be reduced to release valuable alloying elements to the melt apart from creating a dispersion of fine alumina. On solidification, composite containing fine particles of alumina dispersed in a matrix of alloy stronger than aluminium could result. In cast composites made by dispersing externally added alumina in the melt of aluminium or its alloy it is very difficult to introduce particles finer than 10 pin and the resulting composite is generally very brittle. In the laboratory at IIT Roorkee it has been observed that it is possible even to get percent elongation exceeding 10% in aluminium based in-situ composites developed by addition of oxides. Thereafter, investigations in various systems of aluminium and oxides have continued and the present investigation has been carried out in this context. Particle-reinforced metal matrix composites (PMMCs) are attractive to the designers because of their isotropic properties and so, composites have been developed to contain either hard or soft particles or their mixtures embedded in a ductile metal or alloy matrix depending on the targeted application area. Solidification processing of metal matrix composites is of particular interest due to the use of conventional infrastructure of foundries reducing the costs . PMMCs, by combining metallic properties (ductility and toughness) of the matrix with the characteristics of dispersed particles, may often have unique combination of properties like greater strength, higher wear resistance, low friction and higher service temperature capabilities depending on the nature of particles.