Investigation of pressing and sintering parameters of rapidly solidified nickel copper (Monel 400) alloys powders

In this study, Nickel based alloys (Monel 400) was atomized with water jet cooled rotating disc atomization method and rapidly solidified powder was obtained. The produced powders were pressed for different pressures with uniaxial double effect pres. Finally the green parts were sintered in high purity hydrogen atmosphere. Variation of microstructure and microhardness with particle size was investigated. The results showed that the microhardness values increased with decreasing particle size. Fine grained and equiaxed microstructures were seen for small particles and changed to cellular dendritic and dendritic structure with increasing particle size. The produced powders were compacted in uniaxial double effect pres with pressures of 150, 270, 360, 480 and 600 MPa. Apperant density of the powders was measured as 38% and highest green density was obtained as 83% for 600 MPa pressure. Compacted parts were sintered at temperatures of 1100, 1140, 1180 and 1200oC for sintering times of 60, 75, 90 and 105 minutes. The highest sintering density and strength were obtained for 1200oC temperature and 90 minutes. The values were 94% and 258 MPa for 1200oC temperature and 90 minute sintering time, respectively.