Novel Spark Plasma Extrusion of Titanium Above and Below the β-Transus: Effect on Microstructure and Properties

• Published in: Metallurgical and materials transactions. B, Process metallurgy and materials processing science Process metallurgy and materials processing science, 2020-08, Vol.51 (4), p.1363-1369
• Main Authors: Hallett, R., Cox, J. R., Morsi, K.
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Dendritic powders; Extrusion; Hardness; Materials Science; Mechanical properties; Metallic Materials; Microstructure; Nanotechnology; Plasma sintering; Spark plasma sintering; Structural Materials; Surfaces and Interfaces; Thin Films; Titanium; Widmanstatten structure
• ISSN: 1073-5615; 1543-1916
• DOI: 10.1007/s11663-020-01845-5

Spark plasma extrusion is a new process that has recently shown superiority over spark plasma sintering for powder consolidation. This paper represents the first investigation of novel spark plasma extrusion (SPE) of titanium (Ti) powder. Extrusion temperature (above and below the β -transus) and initial Ti powder type were found to have a pronounced effect on the developed microstructures and properties. SPE conducted above the β -transus resulted in the formation of Widmanstatten microstructures in addition to martensitic α ′ upon cooling, which ultimately lead to superior product hardness. SPE processing, microstructure, and properties were found to be affected by the initial Ti powder used, where dendritic Ti powder resulted generally in lower extrusion pressures and products of lower hardness, compared to irregular/angular Ti powder. The results also confirm the superiority of SPE over SPS for Ti (irrespective of initial Ti powder type or extrusion temperature) as related to mechanical behavior.