Microstructure and Mechanical Properties of Titanium Processed by Spark Plasma Sintering (SPS)

Spark plasma sintering (SPS) is emerging as an important processing technique in which powders can be consolidated rapidly with simultaneous application of pressure and current. In the present study, commercially pure titanium was processed by SPS using a three-step sintering process that resulted in 100% densification. The three-step process was arrived at through a comparison with single-step or continuous sintering cycle. Light and scanning electron microscopy showed acicular α-Ti grains with a maximum aspect ratio up to eight and average grain size of 64 μm. Hardness and room temperature uniaxial compressive properties were evaluated and the elastic modulus was determined by nanoindentation and ultrasonic methods. The average hardness was found to be 325 HV0.3. The 0.2% proof stress was 728 MPa and the nominal ultimate compression strength was found to be 1,560 MPa. These values were substantially higher than reported values for CP Ti. Compression samples failed diagonally at angle of about 45° indicating failure along the planes of maximum shear stress. © 2013 Springer Science+Business Media New York and ASM International.