Thermodynamic aspects during the processing of sintered materials

• Thermodynamic aspects have great influence during materials processing and properties.
• Several reactions can occur during processing by powder metallurgy.
• A well designed processing route leads to better material properties.
• The application of thermodynamical concepts increases the materials performance.

This study highlights the thermodynamic aspects that should be considered in the development and processing of powder materials. Several reactions that can occur during sintering of powder mixtures in which particles of different compositions and phases are present, as well as reactions with the furnace atmosphere were discussed. A theoretical basis is presented to predict, evaluate and, in some cases, avoid these reactions. Experiments involving sintering of ferrous materials were performed in order to exemplify the theories addressed in the work. In these experiments were studied the solubility of elementary Mo in Fe–Mo powder compacts, solid lubricant obtaining in situ during sintering by dissociation of silicon carbide, reactions between MoS2 and iron-based matrix, oxidation of a Si-containing alloy, and copper sublimation from 17-4 PH stainless steel parts. The microstructure analysis and properties evaluation of sintered materials indicated to be possible to predict metallurgical aspects using thermodynamic knowledge.

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