Ultralow‐Temperature Sintering of Titanium Powder by Spark Plasma Sintering Under Cyclic Pressure

Abstract

Spark plasma sintering (SPS) is a promising method for producing titanium components from powder but a limitation is that high sintering temperatures (>900 °C) are normally required to eliminate porosity. Herein, the SPS of commercially pure titanium powder is reported using both cyclic and constant uniaxial pressure and compare densification, microstructure, and mechanical behavior. The following parameters are varied: sintering temperature, TS, 400 to 900 °C; cyclic and constant pressures, 100 to 500 MPa; with and without an isothermal dwell of 60 min at TS. The mechanical behavior is determined by bend and tensile testing. It is demonstrated that the application of cyclic pressure (cyclic‐SPS) gives superior densification over the range of parameters investigated compared with a constant pressure. Bend testing reveals improved ductility after cyclic‐SPS compared with a constant pressure. The dwell at TS further improves mechanical properties, giving excellent tensile ductility and strength. Consequently, at the ultralow temperature of 500 °C, nearly fully dense, ductile, titanium is achieved. It is shown that cyclic pressure enhances the degree of powder compaction at room temperature, and mechanisms are proposed to rationalize the effect of cyclic‐SPS on enhancing the rates of densification and sintering as the temperature increases during processing.