Powder Metallurgy Production of Ti-2 Wt Pct Si Alloy: Structural, Mechanical, and Electrochemical Characterization of the Sintered Material

Several commercial alloys use silicon (Si) to improve titanium (Ti) resistance to creep and oxidation at high temperatures and to improve Ti corrosion resistance in acid media. According to the Ti-Si phase diagram, reported stable solid phases in the Ti-rich region are β-Ti, α-Ti, Ti₃Si, and Ti₅Si₃. Nevertheless, very few works in the literature discuss Ti₃Si intermetallic production. As such, this work studied the possibility of obtaining an α-Ti-Ti₃Si alloy by hot pressing α-Ti supersaturated solid solution powders obtained by mechanical alloying. The consolidation of milled powders was performed using uniaxial hot press equipment. Structural and morphological evolutions during the sintering process were investigated by X-ray diffraction and scanning electron microscopy. Electrochemical behaviors of sintered samples were evaluated by open circuit potential and linear sweep voltammetry. Results show a fine and uniform Ti₃Si alloy distribution in the α-Ti matrix produced by the proposed powder metallurgy route. The sintered samples demonstrated high micro-hardness and resistance to sulfuric acid corrosion. Additionally, Ti₃Si was shown to have a significant hardening effect on the α-Ti matrix. Electrochemical behavior further demonstrates that a fine and homogeneous Ti₃Si distribution in the α-Ti matrix contributes to a more stable superficial oxide layer against sulfuric acid corrosion.