Nickel-free beta-titanium Alloy with Large and Stable Room Temperature Superelasticity
S. Cai, J.E. Schaffer
Fort Wayne Metals Research Products Corp, 9609 Ardmore Ave., Fort Wayne, IN 46809, USA
Clinical Radiologic & Imaging Sciences, Indiana University of Medicine, Fort Wayne, IN 46805, USA
Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439, USA
Fort Wayne Metals has developed a Ni-free ß-Ti alloy showing large and stable superelastic properties at room temperatures (Figure 1). Mechanical properties and fatigue performance of this alloy are within the neighborhood of superelastic NiTi alloys. Plateau strengths can be further tuned to a wide range by low temperature aging similar to Ni-rich binary NiTi. It can be manufactured in large industrial scales by commercial production lines, and has been melted in hundreds of kilogram scale. Compared to other published ß-Ti alloys, it is relatively easy to shape set into device subcomponent forms to achieve similar functional performance to Nitinol (Figures 2 and 3). With additional characteristics such as relatively high X-ray visibility (Figure 4), good corrosion resistance and biocompatibility, this alloy provides a superelastic option in Ni-sensitive dental, orthodontic, orthopedic bone staple, and neurovascular applications, to name a few possibilities.
More details can be found in our recent publication on Materials Today Communications. This link provides free access to this article until December 27th, 2020.
Figure 1: Stress-strain curves of samples after stress-relieve heat treatment and room temperature aging for 4 and 10 days showing large and stable superelasticity.
Figure 2: Oblique view of Ø 10x22 mm one-over-one single wire braids produced from 50 µm THNS (left) and Ni50.9Ti49.9 (right) wire.
Figure 3: (a) Load and displacement curves during compression test of Ni50.9Ti49.9 nitinol and THNS wire braid subcomponents with representative (b) compression and (c) recovery images after 9mm digital compression where similar response was observed for bother materials in the Ø 10x22 mm braids.
Figure 4: X-ray images taken at 60 kVp-20 mAs and 100 kVp-2.5 mAs of different alloys: (a,j) L605; (b,k) 316L; (d,m) NiTi-DFT10%Pt; (f,o) NiTi-DFT-20%Pt; (g,p) NiTi-DFT-30%Pt; (h,q) NiTi-DFT-40%Pt; and (i,r) Pt8W as a high opacity baseline. Sample diameters are 0.100 ± 0.010 mm.
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