Microstructural and mechanical correlations of Beta Ti-Nb alloy and TiC-reinforced composites in-situ fabricated by additive manufacturing

• Grant number: 25/08589-0
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor
• Start date: September 30, 2025
• End date: June 29, 2026
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
• Principal Investigator: José Eduardo Spinelli
• Grantee: Vinícius Richieri Manso Gonçalves
• Supervisor: Michael Joseph Kaufman
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Institution abroad: Colorado School of Mines, United States
• Associated to the scholarship: 24/00306-7 - Laser additive manufacturing of Beta Ti-Nb alloy and TiC-reinforced composites designed for biomedical applications, BP.PD

Abstract

This study aims to comprehend the correlations between composition, microstructure, and mechanical properties of newly developed composites intended for biomedical applications. Beta-type titanium alloys, renowned for their low elastic moduli, combined with titanium carbide (TiC) reinforcements, have emerged as promising candidates to meet load-bearing and wear-resistant requirements in bone implant demands. The ongoing Research Project, in Brazil, has studied an innovative approach using laser powder bed fusion (LPBF) to in-situ fabricate TiC-reinforced Beta-TMCs, employing powder mixtures of Beta Ti-42Nb alloy and graphite. Recent results evidenced that graphite additions of 0.5, 1.0, 1.5, and 2.0 vol.% resulted in TiC fractions of approximately 2, 5, 6, and 8 vol.%, respectively, in the as-built samples. Microstructural analysis revealed that elevated graphite content led to the formation of nearly spherical TiC nanoparticles, attributed to the hypereutectic composition, where TiC precipitates as a primary phase, while lower graphite levels led to rod-shaped TiC from tens to hundreds of nanometers. Furthermore, increasing in the TiC fraction enhanced hardness and elastic modulus up to 239 HV and 72 GPa, compared to the unreinforced Ti-42Nb alloy (211 HV and 58 GPa). Notably, all Beta-TMCs exhibited lower elastic moduli than that of the Ti-6Al-4V alloy (~110 GPa), whereas hardness suggested the influence of TiC morphology on the strengthening mechanism. To further understand the microstructural-strengthening relationship, the present project intends to perform tensile tests accompanied by in-situ Scanning Electron Microscopy. In addition, Electron Backscatter Diffraction, X-ray Computed Tomography, and Transmission Electron Microscopy analyses are intended for investigating how the size and shape of TiC influence microstructures and properties of Beta-TMCs. (AU)