Combined Use of SHS and SPS: Important Mechanistic Details

Abstract—The processes of current flow and reaction initiation in a mixture of Ti–Cu spherical particles were studied in model experiments and in real conditions of SPS processing. Our results allow us to conclude that the local overheating during SPS-consolidation of powder materials is caused by the formation of some preferable current pathways within which current density is markedly greater than within the adjacent areas. This leads to the breakdown of thin dielectric layers (oxide films, vacuum nanogaps) at particle-to-particle contacts, the conductivity of this route sharply grows, and the constituent particles become overheated selectively. In turn, local overheating gives start to SHS reaction and formation of reacted areas in the sample bulk. Our results may turn useful to those engaged in the optimization of process charts and process conditions for SPS-consolidation of materials.