正交试验优选TC4钛合金粉体放电等离子烧结工艺

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

通过正交试验方法研究了放电等离子烧结制备TC4钛合金烧结体工艺中温度、压力和保温时间对其相对密度、硬度和显微组织的影响规律,根据烧结体相对密度和硬度优化了烧结工艺参数。结果表明:温度是影响烧结体性能和显微组织的关键因素,压力和保温时间对其影响较小;随着烧结温度升高,烧结体的相对密度逐渐增大,硬度先增大后减小,晶粒逐渐由等轴状向片层状演变,晶粒尺寸变大;随着压力增大,烧结体的相对密度增大,硬度先增大后减小;随着保温时间延长,烧结体的相对密度和硬度均呈递增的趋势;最优的烧结条件为烧结温度850℃、烧结压力40 MPa、保温时间8min,此时烧结体的相对密度和硬度均较高,分别为99.09%和42.3HRC。

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.