Property Improvement of TiNi by Cu Addition for Orthodontics Applications

Abstract

This study aims to investigate mechanical properties and transformation behavior of TiNiCu shape memory alloys to obtain optimal conditions for utilizing as orthodontic wires. TiNi binary alloys with Ni-content 50.6 at.%, TiNiCu alloys with Cu-content ranging from 5 to 10 at.% were prepared. The alloys were melted by electrical arc-melting method and then homogenized at 800°C for 3600 s. The alloys were subsequently sliced into thin plates (1.5 mm) by EDM wire cutting machine. To evaluate mechanical properties, the specimens were cold-rolled with 10, 20 and 30%, followed by heat treatment at 400°C and 600°C for 3600 s, respectively. A Differential Scanning Calorimeter (DSC) was used to detect transformation temperatures. Mechanical properties were evaluated by micro hardness and three-point bending tests. The results showed that transformation temperatures were strongly increased with increasing Ni-content. Moreover, the decrease in transformation temperature after increasing level of cold-rolling reduction ratio suggests that internal stress can depress transformation. However, internal stress seemed to support the introduction of superelasticity for each specimen. In addition, specimens heat treated at 400°C have, more appropriate properties as orthodontic wires than those heat-treated at 600°C due to the remaining effect of cold-working. These results can be take into consideration for optimizing alloy composition and mechanical properties of TiNiCu shape memory alloys for orthodontics wires purposes.

Effect of milling time on the structure, micro-hardness, and thermal behavior of amorphous/nanocrystalline TiNiCu shape memory alloys developed by mechanical alloying

“…However, these properties are significantly altered by a composition deviation and can be considerably improved by the addition of a third element (such as Cu) to the binary compound. By the partial replacement of Ni with Cu, not only the composition sensitivity of the alloy is reduced [8][9][10], but also the corrosion resistance of the alloy can be improved and the transformation behavior and shape memory characteristics can be affected. For instance, a two-stage transformation (cubic-B2 to orthorhombic-B19 and B19 to monoclinic-B19 0 ) occurs by the addition of 10 at.% Cu, whereas a one-stage transformation (B2-B19) occurs provided that the amount of Cu exceeds 10 at.% [7,11].…”

Exploring the Influence of the Microstructure on the Passive Layer Chemistry and Breakdown for Some Titanium-Based Alloys in Normal Saline Solution

“…1. Tables 4 and 5, it is evident that the Ti, Al, Sn and Zr elements tend to segregate to α phase than to β phase [23]. However, V, Nb, Cr and Mo are β forming elements [24], meaning that higher ratios of these elements are found in β phase rather than in α phase.…”

Fabricating TiNiCu Ternary Shape Memory Alloy by Directed Energy Deposition via Elemental Metal Powders

“…The temperature range for the phase transformation becomes longer when the location gets higher, which shows that the homogeneity of martensite is the highest at location H1, and it follows a descending trend when going up along the BD direction [42]. Adding Cu to replace a certain atomic number of Ni was reported to be able to reduce the thermal hysteresis, which is usually defined by the difference between A p and M p [46], or the difference between A f and M s [47]. In this work, the thermal hysteresis calculated by |A p −M p | of these three sections can be found for S12 (11 • C), S23 (12 • C), and S34 (16 • C).…”