Effect of Thermo-Mechanical Treatments on the Microstructure and Mechanical Properties of the Metastable β-type Ti-35Nb-7Zr-5Ta Alloy

Abstract

In this work, theoretical composition design and thermo-mechanical treatments were combined in order to improve the mechanical compatibility of a biomedical β-type titanium alloy. By applying a composition design theory, cold rolling and low temperature aging, a metastable β-type Ti-35Nb-7Zr-5Ta (wt%) alloy with an elastic modulus of 47 GPa and a yield strength of 730 MPa was successfully fabricated. This combination of high yield strength and low elastic modulus resulted in enhanced elastic recoverable strain of 1.7%, which is much higher than that of the conventional metallic biomaterials. The microstructure responsible for the much sought-after mechanical properties was observed to be mainly consisted of a homogeneous distribution of nanometer-sized ω-and α-precipitates in a β-phase matrix obtained via cold rolling plus short-time aging at low temperature, i.e. aging at 673 K for 20 min. These precipitates increase the strength of the material by hindering the motion of dislocations while the β-matrix with relatively low content of β-stabilizers gives rise to the observed low elastic modulus. By extending aging time, a higher strength is reached at the expense of an undesirable increasing in elastic modulus.

A review on β-Ti alloys for biomedical applications: The influence of alloy composition and thermomechanical processing on mechanical properties, phase composition, and microstructure

“…Al's presence in the body raises the risk of Alzheimer's disease. 111 Vanadium (V) ion's presence in the body can change the kinetics of enzymes involved in the inflammatory response. 112 As an alternative to Ti64, another alloy Ti-6Al-7Nb was developed especially for biomedical applications to avoid the toxic element V. Ti-6Al-7Nb is often used for medical equipment such as fracture fixation plates, hip joint stems, fasteners, and wires.…”

A review on various phases and alloy design methods of β-Ti alloys for biomedical applications

“…The alloy showed an elastic modulus of 47 GPa and YS of 730 MPa. 92 Chen et al designed the Ti-Nb-2Ta-3Zr alloys by d-electron method with various Nb compositions, B o ¯ value varied and the M d ¯ value kept constant. As the B o ¯ value increased, up to 35% Nb, the elastic modulus decreased and then increased.…”

Microstructure, Texture Evolution, and Aging Behavior of a Cold‐Rolled Ti–B20 Alloy

“…Generally, SIM transformation readily occurs for β-Ti alloys during cold deformation. [30][31][32][33][34][35][36] The Ti-B20 alloy used in this study is a β-Ti alloy. Nevertheless, SIM transformation does not occur.…”