Phase Constitution and Martensitic Transformation Behavior of Au-51Ti-18Co Biomedical Shape Memory Alloy Heat-Treated at 1173K to 1373K

Abstract

Phase constitution and martensitic transformation behavior were investigated for a Au–51Ti–18Co alloy heat-treated at 1173 K to 1373 K for 3.6 ks. The Au–51Ti–18Co alloy was fabricated by Ar arc-melting technique and subsequently by hot-forging at 1423 K for 10.8 ks. X-ray diffraction analysis revealed that B2 parent phase, B19 martensite phase and AuTi3 simultaneously appeared regardless of the heat-treatment temperatures. By increasing the heat-treatment temperature, the volume fraction of AuTi3 was slightly reduced. Besides, the lattice transformation strain which was calculated from the precisely-determined lattice parameters was evaluated to be 7 % in the Au–51Ti–18Co alloy in all the heat-treated conditions. This value is comparable to that of NiTi practical alloys. From differential scanning calorimetry (DSC) analysis, reverse martensitic transformation temperature was slightly increased with the heat-treatment temperature. From the lattice transformation strain point of views, the Au–51Ti–18Co has a large potential for novel biomedical shape memory alloy.

Mechanical and Superelastic Properties of Au-51Ti-18Co Biomedical Shape Memory Alloy Heat-Treated at 1173 K to 1373 K

“…It was found that the CSS was slightly decreased with increasing heat-treatment temperature in this experimental range, even though there is small deviation in the results of HT1373. It can be understood that, the reduction in the CSS is majorly caused from the decrease in amount of precipitates which already reported in the references [1][2]. Fig.…”

“…In the other words, the SIMT increased with decreasing the M s of the specimen when the testing temperature is kept constant at room temperature. It has been reported that the M s was slightly increased in the higher heat-treatment conditions in the Au-51Ti-18Co alloy [1][2], the reduction in the σ 0.2 is understandable.…”

“…Furthermore, the superelasticity with maximum shape recovery strain of 4 % and the unusual precipitation of Au 3 Ti with L1 2 structure have been reported in this alloy after heat-treatment at 1173 K for 3.6 ks [2][3]. It is also found that the volume fraction of the Au 3 Ti (L1 2 ) precipitates gradually decreases with increasing the heat-treatment temperature from 1173 K to 1473 K [1-2].…”

“…Nowadays, Au-Ti-Co ternary alloys have received a lot of attention owing to their good biocompatible and sufficient X-ray radiographic properties [1][2][3][4]. These features fulfill a drawback of Ni-Ti practical alloys which are the possibility of Ni-hypersensitivity [5][6] and not enough X-ray radiography [7][8].…”

On the design strategies for SMA-based morphing actuators: state of the art and common practices applied to a fascinating case study

“…Au-based biomedical [12][13][14][15] Ni-Ti-based medical instruments (medical implants, 16 stent, 17 orthodontics, 18 surgery, 19 rehabilitation devices 20 ), Aerospace devices (rotary actuators, 21 solar sail, 22 morphing wing 23 ) Cu-based 24 pipe couplings, 25 hydraulic fittings, 26 mechanical dampers, 27,28 energy dissipation devices, 29 textiles 30 Fe-based 31 fishplates for crane rails, 32 pipe couplings, 25 civil structures 33 (concrete reinforcement, 34 damping, 35 pre-stressing elements 36 ) aerodynamic devices. In particular, it can be noted that most of the devices are dealing with aircraft components, with specific regard to wings, and focusing on design, fabrication, testing and modeling aspects.…”