Effect of porosity on compressive yield strength of microwave sintered titanium components

Titanium is widely used in biomedical implants because of its excellent mechanical properties, good biocompatibility and high resistance to corrosion. However, the fabrication of titanium components often involves high cost due to the long processing time and difficulty in metalworking. Powder metallurgy is a near-net-Shape processing method which has the advantage of high production rate with low unit cost. In this study, a technique comprising microwave sintering with powder metallurgy has been developed to fabricate titanium components. Commercially pure titanium powdered compacts, prepared by three initial particle size groups of 10±2 μm, 30±2 μm, and50±2 μm, were sintered in a 1.4 kW, 2.45 GHz microwave multi-mode furnace for 2 minutes using silicon carbide particles as the microwave susceptor to assist the heating. The room temperature deformation behavior of titanium components was investigated. Metallographic studies of the porosity and pore size were undertaken by optical microscopy. The results of this study indicate that irregular shaped pores were uniformly distributed within the sintered specimens. Furthermore, the pore size and porosity of the sintered specimens decrease with decreasing initial particle size. The compressive yield strength showed a linear relationship with the porosity, and was found to follow the Hall-Petch relationship with the initial particle size. This study demonstrated that it is feasible to microwave sinter titanium components having various compressive yield strengths by controlling the initial powder size of the titanium.