Previous studies showed that niobium can largely increase martensitic transformation stresses, stiffness, and radiopacity of NiTi alloys, which are highly demanded by many medical applications.
Nano-size niobium fibers embedded inside a NiTi matrix can produce process-tunable hysteresis from narrow to wide, beneficial for applications ranging from high transformation-stress vascular guidewires, to impact-energy dissipation in automotive structures. Being in the same group in the periodic table as niobium, tantalum has a higher modulus and better radiopacity. Like niobium, it also forms a nearly pure secondary phase in the NiTi matrix during solidification.
In this study, a metal matrix composite comprising Nitinol with varied tantalum area fractions are melted and processed to 0.50 mm diameter wires. Tensile and bending fatigue mechanical properties after various heat treatments are evaluated. In-situ synchrotron X-ray diffraction is used to investigate the stress-induced transformation behavior and the influences of tantalum fibers at the microscopic level. This gives preliminary data to inform applied research in academia and industry.
Abstract of A Nitinol Tantalum Metal Matrix Composite for High Plateau Stress or Energy Dissipation, by Dr. S. Cai, Dr. Jeremy E. Schaffer, Fort Wayne Metals Research Products Corporation, Fort Wayne, Indiana
Presentation is from SMST 2019, May 13 – 17, Kostanz, Germany
