The aim of this study was to investigate the effect of thermomechanical treatment on mechanical and metallurgical properties of nickel-titanium (NiTi) rotary instruments. Eight kinds of NiTi rotary instruments with sizes of ISO #25 were selected: ProFile, K3, and One Shape for the conventional alloy; ProTaper NEXT, Reciproc, and WaveOne for the M-wire alloy; HyFlex CM for the controlled memory-...

The heat of fusion and the specific heats of the solid and liquid have been experimentally determined for a Ti6&r4a alloy. The data are used to evaluate the Gibbs free energy difference, AG, between the liquid and the 0 phase as a function of temperature to verify a reported spontaneous vitrification (SV) of the fi phase in Ti-Cr alloys. The results show that SV of an undistorted fl phase in th...

Structural, gaseous phase hydrogen storage, and electrochemical properties of a series of the Ti50Zr1Ni44X5 (X = Ni, Cr, Mn, Fe, Co, or Cu) metal hydride alloys were studied. X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed the multi-phase nature of all alloys, which were composed of a stoichiometric TiNi matrix, a hyperstoichiometric TiNi minor phase, and a Ti2Ni seconda...

Both the superelastic and the shape memory properties of the cubic NiTi alloy known as Nitinol arise from two-phase transitions; from a simple cubic austenite phase to a trigonal R-phase and to a lower symmetry martensite phase. In this article, we speculate that two competing forces drive these transitions. One is “mechanical” in nature and it takes the cubic austenite structure of NiTi to a d...

Acrylic bone cement has been an essential non-metallic implant used as fixing agent in the cemented total joint arthroplasty (THA). However, the currently available materials based mainly on polymethylmethacrylate (PMMA) still encounter certain limitations, such as time-consuming polymerization, thermal and chemical necrosis and troublesome revision procedure. Here from an alternative way, we p...

High-pressure torsion (HPT) and thermal annealing were applied to a face-centered cubic as-cast Al0.3CoCrFeNi high entropy alloy. Processing by HPT produced a nanostructure with a higher incremental hardness than in most HPT single-phase materials and subsequent annealing at appropriate temperatures gave an ordered body-centered cubic secondary phase with an additional increase in hardness. The...

An overview will be given of some recent results of microstructural electron microscopy studies on martensitic systems. The precursor structure observed in a ternary Ni-Mn-Ti alloy and its correlation with the ensuing stacking sequence is presented. New types of materials of a well known alloy, in casu splat-cooled and nanoscale thin films of Ni-A1 are investigated revealing particular morpholo...