Inhibition of localized corrosion of Ni–Ti superelastic alloy in NaCl solution by hydrogen charging

Rate Dependency During Relaxation of Superelastic Orthodontic NiTi Alloys After Hydrogen Charging

“…In contrast, in the Zhao study they assumed that the hydrides, formed after charging, presented pinning points that increased the internal friction [14]. On the other hand, during aging, the hydrides tended to be decomposed and thus they would affect the decrease in internal friction [13]. In addition, Runciman et al [28] showed that the latent heat, that was responsible for the relaxation behavior of asreceived NiTi, decreased with the increase in the hydrogen amount.…”

“…Cheng et al [12] performed X-ray diffraction and optical microscopy on a charged NiTi alloy and monitored hydride nucleation and growth at grain boundaries. In another work [13], it was noticed that the NiTiH-type hydrides developed after hydrogen charging at a current density of 10 A m -2 in \4 h, then decomposed and disappeared after aging 240 h at ambient conditions. In addition, Zhao et al [14] indicated, in a recent study, that the hydrogen-induced martensite reduced with the formation and growth of the Ti 2 NiH 0.5 -type hydrides that presented pinning points that increased sharply the internal friction.…”

Monitoring Tensile Fatigue of Superelastic NiTi Wire in Liquids by Electrochemical Potential

“…Yokoyama and coworkers systematically investigated embrittlement of hydrogenated NiTi (see [38][39][40] and references there). They hydrogenated NiTi both by exposing it to gaseous hydrogen at high temperatures and by Fig.…”

“…The wire was kept in the elongated state during the SEM observation. While the small oxide cracks (detail in the inset) which are homogeneously dispersed over the wire surface cannot be seen in low magnification, the longer/wider oxide cracks appearing preferentially at inclusions and/or notches are clearly visible the electrolytic route to find out that the adsorbed hydrogen brings about severe decrease of the strength [37,38] and leads to brittle fracture [38,41]. Particularly, they claimed that the hydrogen adsorption rate is much faster, when the NiTi is electrolytically hydrogenated while it transforms during cyclic mechanical loads [40], compared to the cases when it is stress free, under constant stress or cyclically loaded in elastic range.…”

Nondestructive technique application for corrosion evaluation by hydrogen charging of stainless steel

“…Stainless steel is used to transfer and store the hydrogen, and hydrogen embrittlement of stainless steel is a big issue at present researches. Yokoyama tion of the localized corrosion of Ni-Ti superelastic alloy by amount of hydrogen charging [4]. Hasegawa et al researched anomalous corrosion of hydrogen containing ferritic steels in aqueous acid solution, and found that corrosion behavior often depends on the existence of hydrogen in metals and alloys [5].…”