On the Purity and the Mechanical Properties of Crystalline Ti Produced by the Gaseous Reaction of TiCl₄ and Mg

Abstract

The purity and mechanical properties were examined experimentally on crystalline Ti produced by the reaction in the gaseous phase of TiCl₄ and Mg. We found that it had a purity near that of the iodide process Ti by chemical analysis. Even if a slightly low grade of TiCl₄ or Mg was used as the raw material, high purity Ti was obtained owing to the distillation effect followed by the evaporation of TiCl₄ and Mg. The possibility of admixture of Fe from the construction materials of the reaction vessels was specially studied, but it was found that the admixture of Fe was extremely reduced by using a graphite lining on the inner surfaces of leading pipes of TiCl₄ and Ti-coated frames and sleeves. Iron contamination can occur in the case of excess TiCl₄ which may be caused by the fluctuation of the flow rate of both vapours, therefore when the control of the flow rate is kept precisely constant the admixture of Fe could be kept below 0.01%. The hardness of crystalline Ti produced at our laboratory was in the range of 82 to 100 in V.H.N and 85 in the average. Tensile and Charpy impact tests were carried out and we obtained 30∼35 kg/mm² in tensile strength, 13∼20 kg/mm² in yield strength, 84∼82% in reduction of area and 60∼58% in elongation. It was shown that the crystalline Ti has excellent mechanical properties of high ductility in spite of slightly higher strength than the iodide process Ti. In the impact tests the test specimens with V notch and U notch were not broken even in the low temperature range of liquid nitrogen, and it was shown that the impact value of crystalline Ti was higher as the temperature was lowered.