A new ohmic contact scheme for gallium nitride is presented. The use of Nitrideforming metal Over Gallide-forming metal, “NOG”, can modify the thermodynamic activity of N and Ga near the interface. This in turn can modify the near-surface point defect concentrations, particularly the vacancies of Ga and N. The principle of this contact scheme was shown to be consistent with results from Ni/Au, ...

AIM The purpose of this study was to evaluate the load and unload deflection and permanent deformation of round 0.016'' and rectangular 0.016'' × 0.022'' regular and coated Ni-Ti wires. MATERIALS AND METHODS Ni-Ti archwires produced by two manufacturers were evaluated. Both regular and coated round and rectangular Ni-Ti wire segments (n = 15) from each group were submitted to a three-point be...

Surface modification with oxide nanostructures is one of the efficient ways to improve physical or biomedical properties of shape memory alloys. This work reports a fabrication of highly ordered Ti-Ni-O nanotube arrays on Ti-Ni alloy substrates through pulse anodization in glycerol-based electrolytes. The effects of anodization parameters and the annealing process on the microstructures and sur...

While the main features of the Fe–Ni–Ti system are well known at low Ti content, literature review of the Ti-rich corner revealed inconsistencies between experimental reports. This investigation presents new experimental results, defined to remove the uncertainties concerning melting behavior and solid-state phase equilibria of the (Ni,Fe)Ti2 phase with the adjacent (Fe,Ni)Ti (B2, CsCl-type str...

The microstructure of sputter deposited Ti-rich Ni-Ti thin films doped with Cu in the range 020.4 at.% and annealed for 1 h at 500 and 600°C has been investigated and correlated with the mechanical properties of the films measured by depth-sensing nanoindentation. X-ray diffraction analysis showed the microstructural evolution of Ni-Ti thin films when doped with Cu and annealed at different tem...

In the case of medical implants, foreign materials are preferential sites for bacterial adhesion and microbial contamination, which can lead to the development of prosthetic infections. Commercially biomedical TiNi shape memory alloys are the most commonly used materials for permanent implants in contact with bone and dental, and the prevention of infections of TiNi biomedical shape memory allo...

intermetallic phase formation and oxidation reaction during combustion synthesis (cs) of ni-ti equiatomic mixture are affected by mechanical activation (ma) and pre-heating conditions. important parameters are ignition time, reaction duration, temperature rise, microstructural change, titanium oxidation and intermetallic phase formation. superelasticity and shape memory effects are influenced b...

introduction: pulpectomy of primary teeth is commonly carried out with hand files and broaches; a tricky and time consuming procedure. the purpose of this in vitro study was to compare the cleaning efficacy and time taken for instrumentation of deciduous molars using hand k-files and flex master rotary system. materials and methods: in this study, 68 canals of 23 extracted primary molars with a...

This study investigates phase transformation and mechanical properties of porous NiTi alloys using two different powder compacts (i.e., Ni/Ti and Ni/TiH2) by a conventional press-and-sinter means. The compacted powder mixtures were sintered in vacuum at a final temperature of 1373 K. The phase evolution was performed by in situ neutron diffraction upon sintering and cooling. The predominant pha...

Porous NiTi with an average porosity of 55 vol % and a general pore size of 100-600 microm was synthesized by self-propagating high temperature synthesis (SHS) with the addition of mechanically alloyed nanocrystalline Ni-Ti as the reaction agent. The SHS of porous NiTi using elemental powders was also performed for comparison. To enhance the bioactivity of the metal surface, porous NiTi synthes...