Consolidation Behaviors of FeB–25Ni Powders in Spark Sintering and Mechanical Properties of Their Compacts

Abstract

25 vol% Ni electroless-plated FeB powders were consolidated by spark sintering for the development of hard materials. The sintering curves of the FeB–25Ni powders were between those of as-received FeB without Ni addition and pure Ni powders. The maximum densification rate in the FeB–25Ni was achieved at an apparent relative density of 0.79, which was higher than that of the as-received FeB (0.6) and close to that of pure Ni (0.74). The densification of FeB–25Ni was predominantly a result of plastic deformation and power-law creep deformation of the Ni binder. The change in densification mechanism occurred roughly at the maximum densification rate. The sintering curve and densification rate of the FeB–25Ni powders could be explained by the combination of sintering curve and densification rate obtained from the as-received FeB and pure Ni powders. The increase in maximum holding temperature led to the improvement in hardness and compressive and fracture toughness properties, which resulted from the increase in apparent relative density due to the activation of diffusion at the interfaces between particles.