Investigation of vertical gradients and lubrication on the final properties of the Cu-15Fe sintered compacts

This study investigates the vertical distribution of density, microstructure, and hardness in Cu-15Fe sintered compacts to explore how sample length influences the final properties of powder metallurgy (PM) components. The motivation arises from the need to control property gradients in vertically oriented PM parts, which are critical for ensuring uniform mechanical and functional performance. Cylindrical specimens were compacted at 200 MPa with a height-to-diameter (H/D) ratio of 3:1 and sintered at 1100 °C. Solid lubricants including paraffin wax (PW), stearic acid (SA), and their composite (PW+SA) were incorporated to evaluate their effect on densification. The results show a distinct density gradient along the vertical axis, indicating that the bottom region has the highest density, while the top region exhibits the lowest density. This variation is attributed to gravity-induced differential compaction and sintering behavior, which contributes to internal stress development. Among all samples, the PW-lubricated specimen showed a 50% reduction in porosity and the most uniform distribution of density and hardness along the sample height, indicating better compaction and improved material homogeneity.