This study explores reducing the oxygen content of a commercial Ti-48Al-2Cr-2Nb powder to less than 400 ppm by deoxidation in the solid state (DOSS) using Ca vapor, and investigates the effect of Ca vapor on the surface chemical state. As the deoxidation temperature increases, the oxygen concentration of the Ti-48Al-2Cr-2Nb powder decreases, achieving a low value of 745 ppm at 1100°C. When the deoxidation time is increased to 2 h, the oxygen concentration decreases to 320pp m at 1100°C, and the oxygen reduction rate is approximately 78% compared to that of the raw material. The deoxidized Ti-48Al-2Cr-2nb powder maintains a spherical shape, but the surface shape changes slightly owing to the reaction of Ca and Al. The oxidation state of Ti and Al on the surface of the Ti-48Al-2Cr-2Nb powder corresponds to a mixture of TiO₂ and Al₂O₃. As a result, the peaks of metallic Ti and Ti suboxide intensify as TiO₂ and Al₂O₃ in the surface oxide layer are reduced by Ca vapor deposition

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• Production of spherical TiAl alloy powder by copper-assisted spheroidization
  Jin Qian, Bo Yin, Dashun Dong, Geng Wei, Ming Shi, Shaolong Tang
  Journal of Materials Research and Technology.2023; 25: 1860.     CrossRef
• Ca-Mg Multiple Deoxidation of Ti-50Al-2Cr-2Nb Intermetallic Compound Powder for Additive Manufacturing
  Seongjae Cho, Taeheon Kim, Jae-Won Lim
  ECS Journal of Solid State Science and Technology.2022; 11(4): 045008.     CrossRef

In the present work, a new hydrogen added argon heat treatment process that prevents the formation of hydrides and eliminates the dehydrogenation step, is developed. Dissolved hydrogen has a good effect on sintering properties such as oxidation resistance and density of greens. This process can also reduce costs and processing time. In the experiment, commercially available Ti-6Al-4V powders are used. The powders are annealed using tube furnace in an argon atmosphere at 700°C and 900°C for 120 min. Hydrogen was injected temporarily during argon annealing to dissolve hydrogen, and a dehydrogenation process was performed simultaneously under an argon-only atmosphere. Without hydride formation, hydrogen was dissolved in the Ti-6Al-4V powder by X-ray diffraction and gas analysis. Hydrogen is first solubilized on the beta phase and expanded the beta phases’ cell volume. TGA analysis was carried out to evaluate the oxidation resistance, and it is confirmed that hydrogen-dissolved Ti-6Al-4V powders improves oxidation resistance more than raw materials.

Cu-Mn compacts are fabricated by the pulsed current activated sintering method (PCAS) for sputtering target application. For fabricating the compacts, optimized sintering conditions such as the temperature, pulse ratio, pressure, and heating rate are controlled during the sintering process. The final sintering temperature and heating rate required to fabricate the target materials having high density are 700°C and 80°C/min, respectively. The heating directly progresses up to 700°C with a 3 min holding time. The sputtering target materials having high relative density of 100% are fabricated by employing a uniaxial pressure of 60 MPa and a sintering temperature of 700°C without any significant change in the grain size. Also, the shrinkage displacement of the Cu-Mn target materials considerably increases with an increase in the pressure at sintering temperatures up to 700°C.

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• Fabrication and Mechanical Property of Fe-20Cu-1C Compacts by SPS process with Different Heating Rate
  Jung-Han Ryu, Soo-Sik Shin, Byung-Rok Ryu, Kyung-Sik Kim, Jun-Ho Jang, Ik-Hyun Oh, Kap-Tae Kim, Hyun-Kuk Park
  Journal of Korean Powder Metallurgy Institute.2017; 24(4): 302.     CrossRef