Optimization of Spark Plasma Sintering Technology for TC4 Titanium Alloy Powder by Orthogonal Experimentation

An orthogonal approach of experimentation was employed to study the effects of temperature, pressure and holding time on relative density, hardness and microstructure of TC4 titanium alloy sintered compact which were prepared by spark plasma sintering technique. The sintering process parameters were optimized on the basis of the relative density and hardness of the sintered compact. The result show that the sintering temperature was the most essential factor on relative density, hardness and microstructure of the sintered compact, while the pressure and the holding time had less influences. With the increase of sintering temperature, relative density of the sintered compact increased gradually and the hardness firstly increased and then decreased, meanwhile the microstructure gradually changed from equiaxed grain to lamellar structure, and the grain size increased. With the increase of pressure, the relative density of the sintered compact increased and its hardness firstly increased and then decreased. With the increase of holding time, both relative density and hardness increased. The optimal sintering parameters was obtained as follows: temperature of 850 ℃, sintering pressure of 40 MPa, holding time of 8 min. At the parameters, the sintered compact exhibited higher relative density of 99.09% and hardness of 42.3 HRC.