Abstract

Hydrogen sintering phase transformation (HSPT) is a low-cost, blended elemental, press and sinter powder metallurgy process. During HSPT, compacts of TiH2 powder are sintered in dynamically controlled partial pressures of hydrogen followed by a vacuum anneal (dehydrogenation). The use of hydrogen in the sintering atmosphere allows phase transformations in the Ti – H system to create an ultra-fine lamellar microstructure in the as-sintered state with mechanical properties that exceed ASTM standards. Additionally, the fine lamellar structure allows for secondary heat treatments to produce wrought-like microstructures. The removal of hydrogen in the dehydrogenation step is critical to prevent hydrogen embrittlement. The kinetics of dehydrogenation are discussed, in which a model for the concentration profile and an empirical equation for maximum hydrogen concentration as a function of time and size are developed.

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