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Effects of Spark Plasma Sintering on Binary Diffusion of Beta Phase Ti-Nb

  • Author(s): Middleton, Stoney
  • Advisor(s): Lavernia, Enrique J
  • et al.
Abstract

Interest in titanium for mass-scale applications has driven an exploration for rapid, cost-effective consolidation of titanium powders. The effects of electric current and pressure on binary diffusion in beta phase titanium niobium are studied to enhance understanding of Spark Plasma Sintering (SPS), an advanced powder consolidation technology. Binary diffusion couples were annealed in the SPS system, as well as a custom-fabricated load-free furnace, for one hour to elucidate the influences of pressure and current at 1000, 1100, and 1150 C. The results show Ti-Nb interdiffusion coefficient dependence on composition, temperature, current, and pressure. Compared to published results, the activation energy for low concentration Nb, 10-22 at%, has shown to be reduced in the SPS by an average 38kJ/mol at 15MPa and 70kJ/mol at 80MPa. The effect on activation energy of direct current without pressure, at a similar current density as the SPS, shows an average decrease of 105kJ/mol. The possible mechanisms for these changes are discussed, and concepts for subsequent studies are provided.

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