Influence of processing parameters on dehydrogenation of TiH2 in the preparation of Ti–Nb: A review

Abstract

Commercially pure titanium (cp-Ti) and Ti–6Al–4V alloy have emerged as excellent candidates for use as biomaterials in medical implants due to their high strength-to-weight ratio and biocompatibility. β-type Ti alloys composed of non-toxic metallic elements such as niobium (Nb) have been extensively studied in order to resolve the issue of a high elastic modulus and toxicity of certain elements, particularly in Ti–6Al–4V alloy. Titanium hydride (TiH2) has recently received a lot of attention due to its densification, oxidation levels, and material costs. Powder metallurgy combined with mechanical alloying has become an attractive route for producing near-net shape components of Ti-based alloys, mainly where porosity control and better homogeneity are required. This review aims to create a platform for investigating the feasibility of producing Ti from TiH2 via a dehydrogenation process. The dehydrogenation behaviour of TiH2 is affected by variables such as sintering condition, alloying element, and particle size. The review revealed that TiH2 decomposition occurs at various temperatures (400 °C to 800 °C), resulting in the formation of several sequences of phases. Although the dehydrogenation process was unaffected, the addition of alloying elements was found to change the starting and ending temperatures of the reactions. The use of vacuum accelerates the dehydrogenation process more than argon flow. TiH2 powder with smaller particle size, on the other hand, eliminates hydrogen faster than larger ones due to the larger surface area exposed. This review also looks at the best processing conditions for getting a high concentration of β phase in Ti–Nb alloys. β-type titanium alloys with a low elastic modulus (10–40 GPa) similar to human bone are a potential strategy for reducing premature implant failure.