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.

中文翻译：

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SHS和SPS的组合使用：重要的机械细节

摘要

在模型实验和SPS加工的实际条件下，研究了Ti-Cu球形颗粒混合物中的电流流动和反应引发过程。我们的结果使我们得出结论，粉末材料在SPS固结过程中的局部过热是由一些优选的电流通路的形成引起的，其中电流密度显着大于相邻区域内的电流密度。这导致在粒子与粒子之间的接触处击穿薄的介电层（氧化膜，真空纳米间隙），这种途径的电导率急剧增长，并且构成的粒子有选择地过热。反过来，局部过热使SHS反应开始，并在样品块中形成反应区域。