Spark Plasma Sintering Process as a Tool for Achieving Microstructural Integrity

The fact that real materials are not perfect crystals, is critical to materials engineering as the presence of crystalline defects is the most important feature of the microstructure which influences the mechanical properties. Exposure of materials to high temperature for long duration would result in structural failure, when a sub-size crack grows into a critical level. This paper concentrates on the novel application of spark plasma sintering (SPS) technique in achieving microstructural integrity of materials by crack closure using the superior capability of SPS for annealing the defects in materials. Due to the presence of applied compressive stress, expansion is restricted and brings about the closure of cracks. The crack surfaces then come in contact with each other, and energization between the crack surfaces causes them to bond. The presentation would bring about the nature of bonding achieved through SPS when two model systems, diffusion bonding of stainless steel discs and stainless steel with ferroboron powder, were considered and highlighted its applicability through systematic optimization.