Effect of reinforcement particle size on Fe-Cr-AL2O3 Metal Matrix composite

Abstract

Particulate reinforced iron-based composite has unique properties are of interest for a variety of industrial application. However, the properties of such composites are still unrevealed due to limited investigation. In this study, iron-based composites of Fe-Cr reinforced with Al2O3 is produced using solid state route of conventional powder metallurgy technique. A range of reinforcement size of the reinforcing powders (13, 23, 24 and 64 µm) are mixed with the metal powders, compacted and sintered. A green compact was prepared by mixing at 250 rpm for 30 minutes, uni- xially pressed at 750 MPa and vacuum sintered at 1100°C for two hours at 10°C/min heating rate. The effect of reinforcement particle size on the composites is investigated using SEM, EDX, XRD, micro-Vickers hardness and Archimedean principle according to ASTM B311 – 93, to determine the properties of the composites. Experimental data show that a smaller size of reinforcement particle (13 μm) resulted in better properties of the composites compared to a sample with bigger size of the reinforcement. Microstructure of composite with smaller reinforcement size is homogeneous meanwhile the porosity was found to increase with increase in reinforcement size. Consequently the micro-Vickers hardness reading is higher for the composites with smaller reinforcement size. The micro-Vickers hardness reading for the composite with smallest reinforcement is 86.68HV and for the composite with biggest reinforcement size is 46.16HV.