Ti-Mo alloys with various Mo contents from 6wt% to 14wt% were processed by spark plasma sintering based on elemental pow- ders. The influence of sintering temperature and Mo content on the microstructure and mechanical properties of the resulting alloys were investigated. For each Mo concentration, the optimum sintering temperature was determined, resulting in a fully dense and uniform microstructure of the alloy. The optimized sintering temperature gradually increases in the range of 1100-1300℃ with the increase in Mo content. The microstructure of the Ti-（6-12）Mo ahoy consists of acicular α phase surrounded by equiaxed grains of 13 phase, while the Ti-14Mo al- loy only contains single 13 phase. A small amount of fine α lath precipitated from 13 phase contributes to the improvement in strength and hardness of the alloys. Under the sintering condition at 1250℃, the Ti-12Mo alloy is found to possess superior mechanical properties with the Vickers hardness of Hv 472, the compressive yield strength of 2182 MPa, the compression rate of 32.7%, and the elastic modulus of 72.1 GPa. These results demonstrate that Ti-Mo alloys fabricated via spark plasma sintering are indeed a perspective candidate alloy for dental applications.
A numerical model was developed to simulate the jet-flow solid fraction of W18Cr4 V high-speed steel during spray forming. The whole model comprises two submodels: one is an individual droplet model, which describes the motion and thermal behaviors of individual droplets on the basis of Newton's laws of motion and the convection heat transfer mechanism; the other is a droplet distribution model, which is used to calculate the droplet size distribution. After being verified, the model was used to analyze the effects of parameters, including the initial gas velocity, deposition distance, superheat degree, and the ratio of gas-to-metal mass flow rates, on the jet-flow solid fraction. Finally, an equation to predict the jet-flow solid fraction directly and conveniently according to the parameters was presented. The values predicted by the equation show good agreement with those calculated by the numerical model.
