Powder Metallurgy Ti-6Al-4V Alloy with Wrought-Like Microstructure and Mechanical Properties by Hydrogen Sintering

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.

• Periodical: Key Engineering Materials (Volume 704)
• Pages: 3-14
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.704.3
• Online since: August 2016
• Authors: Matt Dunstan, Zhigang Zak Fang*, Mark Koopman, James Paramore
• Keywords: Hydrogen, Kinetics, Mechanical Properties, Microstructure, Powder metallurgy, Titanium

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