Effects of Cold Rolling Deformation and Solution Treatment on Microstructural, Mechanical, and Corrosion Properties of a Biocompatible Ti-Nb-Ta-Zr Alloy

Abstract

One of the most important requirements for a metallic biomaterial is the mechanical biocompatibility, which means excellent mechanical properties—high strength and fatigue strength, but low elastic modulus, to be mechanically harmonized with hard tissues. In order to improve the mechanical and biocompatible performance of the Ti-25.5Nb-4.5Ta-8.0Zr wt% alloy, the influence of cold plastic deformation and solution treatment on its properties were investigated. The Ti-25.5Nb-4.5Ta-8.0Zr wt% alloy was fabricated by melting in a cold crucible furnace (in levitation) and then subjected to several treatment schemes, which include cold rolling and different solution treatments. Microstructural and mechanical characteristics of specimens in as-cast and thermo-mechanically processed condition were determined by SEM microscopy and tensile testing, for different structural states: initial as-cast/as-received, cold rolled and solution treated at different temperatures (800, 900, and 1000 °C) and durations (5, 10, 15, and 20 min), with water quenching. It was concluded that both cold rolling and solution treatment have important positive effects on structural and mechanical properties of the biomaterial, increasing mechanical strength and decreasing the elastic modulus. Samples in different structural states were also corrosion tested and the results provided important information on determining the optimal processing scheme to obtain a high-performance biomaterial. The final processing route chosen consists of a cold rolling deformation with a total deformation degree of 60%, followed by a solution heat treatment at 900 °C with maintenance duration of 5 min and water quenching. By applying this thermo-mechanical processing scheme, the Ti-25.5Nb-4.5Ta-8.0Zr wt% alloy showed an elastic modulus of 56 GPa (5% higher than in the as-cast state), an ultimate tensile strength of 1004 MPa (41.8% higher than in the as-cast state), a yield strength of 718 MPa (40.6% higher than in the as-cast state), and increased corrosion resistance (the corrosion rate decreased by 50% compared to the as-cast state).

The Effect of Solution Treatment Duration on the Microstructural and Mechanical Properties of a Cold-Deformed-by-Rolling Ti-Nb-Zr-Ta-Sn-Fe Alloy

“…Also, it can be remarked that the TNZTSF alloy subjected to cold deformation by rolling (CR) does not present discontinuities in volume, proving that the alloy's microstructure remained homogeneous/undamaged even after applying intense cold deformation (60% deformation degree). Similar observations were also recorded in other studies performed on various types of Ti-based alloys [46][47][48].…”

Effects of Cold Rolling or Precipitation Hardening Treatment on the Microstructure, Mechanical Properties, and Corrosion Resistance of Ti-Rich Metastable Medium-Entropy Alloys

“…In addition, the phase boundaries of multi-phase alloys are also high-energy areas that are prone to preferential corrosion. Furthermore, several studies have shown that the Ecorr value of Ti alloys decreased significantly after cold working [48][49][50][51]. However, this study found that the Ecorr value of the Ti80-Nb10-Mo5-Sn5 significantly increased after cold rolling.…”

Evolution of Microstructural and Mechanical Properties during Cold-Rolling Deformation of a Biocompatible Ti-Nb-Zr-Ta Alloy

“…Mechanical characterization by tensile tests was performed using a GATAN Micro Test-2000N testing machine (Gatan Inc., Pleasanton, CA, USA), with a strain rate of 1 × 10 −4 s −1 . The tensile testing procedure is presented in detail in a previous paper [ 51 ]. Mechanical characterization by micro-hardness testing was performed using an INNOVATEST Falcon 500 (INNOVATEST Europe BV, Maastricht, Netherlands) equipment with a 200 gf testing force and a 30 s dwell time.…”