Heating rate effects on properties of powder metallurgy Fe-Cr-Al2O3 composites

Abstract

The aim of this study is to determine the optimum heating rate in fabricating Fe-Cr-Al2O3 composites by powder metallurgy methods. The Fe-based composites reinforced with ceramics are widely used due to their high strength, hardness and wear resistance. Among steps in powder metallurgy methods are mixing, compaction and sintering. Sintering is a very important step due to its ability to evolve microstructural features that govern the end properties. Sintering of green compacts made of iron powder mixture must be performed in vacuum or in a reducing atmosphere because water-atomised iron powder particles are oxidized on the surface and in this way some deoxidation reaction can occur during sintering. The heating process up to sintering temperature, plays a major role, the major proportion of densification occurs during the heating process. The composites produced were subjected to the following tests: densification, Vickers micro hardness, microstructure using SEM and X-ray diffraction analysis. From this investigation, to achieve higher densification and hardness the optimal heating rate is 10°C/minute. X-Ray Diffraction study showed that the fabrication of the composites does not lead to any compositional changes of the matrix phase and the reinforcing phase.