Low-oxygen Ti-6Al-4V alloy powder synthesized by an aluminothermic reduction combined with deoxidation process

Abstract

A novel aluminothermic reduction combined with deoxidation process was developed in this research to prepare low-oxygen Ti-6Al-4V alloy powder. First, with Al and Al-V alloy powders as reducing agents and additives, crude Ti-6Al-4V alloy powder was fabricated by reduction-vacuum distillation using Na2TiF6 as a titanium source. The aluminothermic reduction process was investigated by TG-DSC technique, and the thermal kinetic parameters of the reaction process were calculated by the Kissinger method. The oxygen content of the crude Ti-6Al-4V alloy powder with a coral-like porous structure was detected as 0.366 %. Furthermore, the existential states of the oxygen contained in the crude product powder was analyzed using XPS. The results indicated that the oxygen existed in three chemical states: metal oxides, defective oxygen, and adsorbed oxygen. Therefore, the deoxygenation of the crude Ti-6Al-4V alloy powder with calcium as a deoxidizer was carried out at 900 °C. As a result, the final Ti-6Al-4V powder with an oxygen content of approximately 822 ppm could be obtained. The contents of Ti, Al, V, Fe, and O in the obtained Ti-6Al-4V powders met the requirements of GB/T 3620.1−2016. This work had demonstrated the feasibility of preparing Ti-6Al-4V alloy powder by the novel aluminothermic reduction combined with deoxidation process.