Design, Fabrication and Characterization of a Quasi-Stable Titanium-Based Gum Metal Alloy

Abstract

Quasi-stable Gum-metal alloys are regarded as promising candidates for medical applications due to their favorable mechanical properties, thermal stability, and biocompatibility. In this study, a suitable composition of this alloy system was designed and synthesized based on thermodynamic criteria, emphasizing properties essential for dental implant fabrication. The initial step involved designing a Gum-metal alloy with targeted characteristics by employing thermodynamic parameters such as bond order (݋ܤതതതത), metal d orbital energy level (݀ܯതതതതത), electron-to-atom ratio (e/a), and atomic radius difference (ݎοതതത), along with calculations based on the CALPHAD database. This composition contained 58% titanium, 37.5% niobium, and 4.5% zirconium, and the values obtained for the indices ݋ܤതതതത, ݀ܯതതതതത, e/a, and ݎοതതത in this composition were 2.87, 2.45, 4.24, and 0.377, respectively, which are within the permissible range for Gum-metal alloys. Following this design, the alloy was produced via vacuum arc remelting (VAR), and the cast ingot was subjected to homogenization, followed by hot and cold rolling processes. To characterize the produced samples, techniques including X-ray diffraction (XRD), transmission electron microscopy (TEM), optical microscopy (OM), and hardness testing were employed. The results indicated that the cast sample primarily consisted of a single β-phase structure. This phase remained dominant throughout the homogenization and deformation stages. Notably, under hot and cold rolling conditions, secondary phases such as α′, α′′, and ω were observed to form within the microstructure. Additionally, cold rolling resulted in the highest increase in hardness (252±6 HV) and dislocation density (3.00×1014 cm-2). Ultimately, the findings demonstrate that, due to the stability of the β-phase and desirable structural properties, this alloy system holds potential as a suitable material for manufacturing dental and orthopedic implants.