Influence of partial titanium substitution by its hydride on structure and mechanical properties of TNM-B1 heat-resistant alloy, obtained by SHS powder hot isostatic pressing

This paper investigates the influence of partial substitution of titanium by its hydride on the microstructure and mechanical properties of TNM-B1 alloy obtained by powder metallurgy technology. The impact of the Ti:TiH₂ ratio in the reaction mixture and heat treatment modes on the microstructure and mechanical properties of TNM-B1+1%Y₂O₃ alloy, obtained using high-energy ball milling (HEBM), selfpropagating high-temperature synthesis (SHS), and hot isostatic pressing (HIP) methods, has been examined. It was observed that a 10 % substitution of titanium with its hydride in the reaction mixtures reduces the oxygen content in SHS products from 1 % to 0.8 % due to the generation of a reducing atmosphere during the decomposition of TiH₂ in the combustion wave. When the Ti : TiH₂ ratio is 90 : 10, highest mechanical properties of TNM-B1+1%Y₂O₃ alloy were achieved: a compressive strength (σ_u) of 1200±15 MPa and a yield strength (YS) of 1030±25 MPa. An increase in the proportion of TiH₂ results in a higher content of oxygen impurity, leading to the formation of Al₂O₃, which reduces the strength and ductility of the material. With additional heat treatment of TNM-B1+1%Y₂O₃ alloy, the globular structure transforms into a partially lamellar one, leading to an increase in σ_u by 50–300 MPa, depending on the TiH₂ content. This attributed to a decrease in the average grain size and a reduction in dislocation mobility during deformation.

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