In the actuation field, the most common shape memory alloy is quasi-equiatomic NiTi system, commercially known as Nitinol®. Ti-rich NiTi compounds show characteristic transformation temperatures higher than the room one and they can recover high values of deformation. Moreover, these intermetallic compounds are widely used since they exhibit high thermal and mechanical cycling stability. Other ...

A new powder metallurgy technique for creating porous NiTi is demonstrated, combining liquid phase sintering of prealloyed NiTi powders by Nb additions and pore creation by NaCl space-holders. The resulting foams exhibit well-densified NiTi–Nb walls surrounding interconnected pores created by the space-holder, with controlled fraction, size, and shape. Only small amounts of Nb (3 at.%) are need...

Functionally graded NiTi structures benefit from the combination of the smart properties of NiTi and those of functionally graded structures. This article provides experimental data for thermomechanical deformation behaviour of microstructurally graded, compositionally graded and geometrically graded NiTi alloy components, related to the research article entitled "Functionally graded shape memo...

Since the introduction of engine-driven nickel-titanium (NiTi) instruments, attempts have been made to minimize or eliminate their inherent defects, increase their surface hardness/flexibility and also improve their resistance to cyclic fatigue and cutting efficiency. The various strategies of enhancing instrument surface include ion implantation, thermal nitridation, cryogenic treatment and el...

The shape memory effect and superelastic properties of NiTi (or Nitinol, a nickel-titanium alloy) have already attracted much attention for various biomedical applications (such as vascular stents, orthodontic wires, orthopedic implants, etc). However, for vascular stents, conventional approaches have required coating NiTi with anti-thrombogenic or antiinflammatory drug-eluting polymers which a...

An access device using a combination of a compression coil spring made of NiTi shape memory alloy (SMA) and NiTi superelastic strips has been developed. Particular consideration is given to the application of the concept in transanal endocopic microsurgery (TEM), but it could be used in other procedures where tissue expansion is required. In TEM, it could realize the gasless dilation of the rec...

When deposited at room temperature, sputtered NiTi thin films are amorphous and need to be crystallized before they can be used as a functional material. We present the results of an annealing study on substrate-constrained NiTi shape memory thin films. Amorphous films of a NiTi shape memory alloy were deposited by UHV sputtering. Films of thickness 1.0 μm were grown on (100) Si wafers both wit...

Microstructural evolution of NiTi shape memory alloy (SMA) with a nominal composition of Ni50.9Ti49.1 (at %) is investigated on the basis of heat treatment and severe plastic deformation (SPD). As for as-rolled NiTi SMA samples subjected to aging, plenty of R phases appear in the austenite matrix. In terms of as-rolled NiTi SMA samples undergoing solution treatment and aging, Ni4Ti3 precipitate...

INTRODUCTION The aim of the present study was to evaluate the bending properties of Hyflex instruments, which exhibit a lower percent in weight of nickel (52 Ni %wt) and compare them with other commercially available nickel-titanium (NiTi) rotary instruments. METHODS Ten instruments with tip size 25, 0.06 taper of each of the following NiTi rotary instrumentation techniques were selected for ...

Because of its good radiopacity, superelasticity, and shape memory properties, nickel-titanium (NiTi) is a potential material for fabrication of stents because these properties can facilitate their implantation and precise positioning. However, in vitro studies of NiTi alloys report the dependence of alloy biocompatibility and corrosion behavior on surface conditions. Surface oxidation seems to...