No abstract

Magnesium metal matrix composites (MMCs) have been receiving attention in recent years as an attractive choice for aerospace and automotive applications because of their low density and superior specific properties. Using stir casting process, AZ91 magnesium alloy metal matrix composites have been produced with different weight percentages (5, 10, 15, 20 and 25) of silicon carbide particles (SiCp) addition. Microstructural characterization reveals uniform distribution of SiC particles with good interfacial bonding between the matrix and reinforcement. Electrical conductivity and Co-efficient of Thermal Expansion (CTE) measurements carried out on these composites have yielded better properties. Improved mechanical properties such as hardness, ultimate tensile strength, and compressive strength are obtained. The microfracture mechanisms involved during tensile fracture is analyzed and correlated with the properties obtained.

Tribological attributes of Mg-alloy (AZ91D) based composites reinforced with 5, 10, 15, 20 and 25 wt% of silicon carbide particle (SiC p) synthesized by stir casting technique are being investigated. The composites show uniform distribution of SiC p and possess refined grains in comparison with the monolithic alloy. The cleaner interface depicts splendid interfacial bonding. The dry sliding wear behavior of the composites has been characterized using a pin on disc wear testing machine at two different normal loads of 19.6 and 39.4N. The volumetric wear rate, wear resistance and coefficient of friction for the composites shows phenomenal variations with fluctuations in load and SiC p content. Scanning electron micrographs of wear surface and wear debris provide excellent insight of the type of wear involved.

In situ Mg-AlN composite has been synthesized by nitrogen gas bubbling method. The morphology of the particles is found to be hexagonal by SEM. The size of the AlN particles is found to be in the range from nano, submicron to a few microns. XRD analysis of the samples confirms the formation of AlN in the melt. Further, the grain size of the magnesium matrix has been reduced by the presence of AlN particles. Hardness of the composite is significantly increased in the particle rich area due to the presence of hard AlN particles.