Densification and microstructural development of stainless steel powder during hot powder vehicle compaction was investigated. The preheated powder preform, vacuum encapsuled in a borosilicate glass, was compacted in a steel die using preheated alumina granules as a pressure transmitting medium. The condition for the full densification was determined as a function of pressure and temperature. Three microstructural features were observed during the compacting process; solutioning of dendritic structure, recrystallization and normal grain growth, each of which was found to be mainly dependent on preheating temperature. It has been found that a submicron-sized microstructure is formed during the recrystallization stage. Kinetic analysis showed that plastic flow is a dominant mechanism of densification of the present compaction process.
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