In-Situ Precipitated Needle Like Nanocrystalline β-Ti Reinforced Porous Titanium Alloy via Molten Salt Electrolysis

Fabricating porous active metals through chemical dealloying poses challenges due to their reactivity and vulnerability to oxidation in aqueous solutions. The objective of this study was to create micron-sized porous Ti alloy by utilizing the Ti–Mo system as a precursor alloy for chemical dealloying. The impact of phase composition and initial microstructure of the precursor alloys (Tix at% Mo100 − x at%, x = 60 ~ 70) on the morphology of the resulting porous Ti alloy was systematically investigated. To improve the mechanical strength and minimize oxidized phases during the dealloying process, a molten salt electrolysis (MSE) method was employed. The strengthening mechanism of MSE on porous Ti alloys encompassed three key aspects. Firstly, it effectively reduced the presence of oxidized phases, thereby eliminating surface defects. Secondly, MSE facilitated grain growth and eliminated voids and cracks at the grain boundaries, leading to enhanced mechanical properties. Thirdly, the involvement of a secondary phase contributed to the overall strengthening mechanism. Following MSE treatment, the oxygen content in the porous Ti alloy decreased from over 13 to 5 at%, and needle-like nanocrystalline β-Ti precipitates formed within the ligament structure. The accumulation and aggregation of compression-induced dislocations at the grain boundaries of the precipitated phase further improved the mechanical properties. In summary, this work presents an innovative approach to fabricating porous Ti alloy with low oxygen content, high strength, and adjustable microstructure. It elucidates the strength enhancement mechanism by MSE, providing insights for future materials development and applications. Graphic abstract: [Figure not available: see fulltext.].