In this experiment, we carried out a two-step deoxidation process to obtain Ti ingots with low oxygen concentration from commercial Ti powder. The first step was to primarily reduce oxygen in Ti powder using Ca and the second was to melt the deoxidized Ti powder in Ar atmosphere with added hydrogen using a vacuum arc melting system. We used two types of raw Ti powder, one with a high oxygen concentration of 5,600 ppm and average powder size of 35 µm, and the other with 2,200 ppm and 115 µm. The high oxygen of 5,600 ppm in the Ti powder was reduced to approximately 1,460 ppm by the two-step process of melting after deoxidizing the Ti powder with Ca at 973 K. On the other hand, in the case of the Ti powder with low oxygen of 2,200 ppm, the Ti ingot with low oxygen of 600 ppm could be prepared by the twostep process of melting after deoxidizing at 1,103 K. The Vickers hardness and c/a value of Ti ingots decreased as the oxygen concentration decreased.

In this study, we carried out an electron beam (EB) melting purification process to obtain a 5N-grade high-purity Ru ingot from commercial Ru powder. The first step was to primarily sinter Ru powder compact by means of vacuum heat treatment at 1,773 K. Vacuum sintering was employed to ensure a high vacuum condition during EB melting by the removal of remaining gaseous elements between the compact powders. The second step was to obtain Ru ingots by EB melting of the sintered Ru compact. The purity of the Ru raw powder was 99.962 mass% and the purity of a premelted Ru button ingot obtained by EB melting was 99.9873 mass%. The purities of the respective Ru button ingots remelted for 2 and 4 min were 99.9988 and 99.9992 mass%, respectively. As a result, the sum of metallic impurities in the Ru ingot refined for 6 min was 5.3 mass ppm and the purity of the ingot considerably increased up to 99.9995 mass%, which means that a 5N-grade high-purity Ru ingot can be obtained by the EB melting purification process. Furthermore, the EB-melted Ru ingot showed an excellent ability to remove interstitial impurities.