A Comparative Study on Ex-Situ & In-Situ Formed Metal Matrix Composites

An attempt has been made to synthesize the aluminium based ex-situ (Al-SiC) and in-situ (Al-TiB2) formed metal matrix composites with varying weight percentage of reinforcement contents such as 4wt.%, 6wt.% and 8wt.%. Synthesized composites were subjected to a cold extrusion process followed by heat treatment according to the ASTM B 918-01 standards. The mechanical properties of in-situ composites were evaluated as per the ASTM guidelines and compared with ex-situ formed composites and base metal properties. Superior properties were noticed in the in-situ formed composites and the mechanical properties such as yield strength, Ultimate tensile strength (UTS) and Hardness for both ex-situ and in-situ composites were found to increase with increasing the reinforcement addition. Cold extruded Al-8 wt.% SiC composite properties such as hardness, yield strength and UTS are 87 RB, 152 MPa, 216 MPa respectively. Whereas, for Al-8 wt.% TiB2 composite, the corresponding properties are 94 RB, 192 MPa, 293 MPa. The morphology of the composites is analysed by Optical and Scanning Electron Microscopic (SEM) whereas presence of reinforcement particles such SiC and TiB2 along with intermetallic phases Mg2Si and Al5FeSi are confirmed by EDX, XRD and Element Mapping analyses.