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Oxidation Behavior of Zr–1Nb Corroded in Air at 400 °C after Plasma Immersion Titanium Implantation
(2018)
In this paper, the influence of plasma immersion titanium implantation into the zirconium alloy Zr-1Nb on the oxidation behavior at 400 °C for 5, 24, 72, and 240 h in air under normal atmospheric pressure (101.3 kPa) was shown. The influence of implantation on the protective properties of the modified layer was shown. The valence of the oxides before and after implantation was analyzed by means of X-ray photoelectron spectroscopy (XPS). Grazing incidence X-ray diffraction (GIXRD) was carried out to examine the phase composition after titanium ion implantation and oxidation. Differential scanning calorimetry (DSC) revealed that titanium implantation exhibited effects of stabilizing the β phase. The formation of the t-ZrO2 and m-ZrO2 was observed during the oxidation of the as-received and modified Zr-1Nb. The measurement of weight gain showed an improvement in oxidation resistance of Ti implanted Zr-1Nb at the oxidation up to 24 h when compared with that of the as-received Zr-1Nb. However, at longer oxidation cycle the oxidation rate of Ti-implanted zirconium alloy is the same with the as-received alloy, which attributed to the layer thickness. Nevertheless, the corrosion of the Ti-implanted alloy is more uniform, while a local corrosion and cracks was detected on the surface of the as-received alloy.
Hydrogen Interaction with Deep Surface Modified Zr-1Nb Alloy by High Intensity Ti Ion Implantation
(2018)
A deep surface modified TiZr layer was fabricated by high-intensity low-energy titanium ion implantation into zirconium alloy Zr-1Nb. Gas-phase hydrogenation was performed to evaluate protective properties of the modified layer against hydrogen permeation into Zr-1Nb alloy. The effects of ion implantation and hydrogen on microstructure, phase composition and elemental distribution of TiZr layer were analyzed by scanning electron microscopy, X-ray diffraction, and glow-discharge optical emission spectroscopy, respectively. It was revealed that TiZr layer (~10 μm thickness) is represented by α′ + α(TiZr) lamellar microstructure with gradient distribution of Ti through the layer depth. It was shown that the formation of TiZr layer provides significant reduction of hydrogen uptake by zirconium alloy at 400 and 500 °C. Hydrogenation of the modified layer leads to refinement of lamellar plates and formation of more homogenous microstructure. Hydrogen desorption from Ti-implanted Zr-1Nb alloy was analyzed by thermal desorption spectroscopy. Hydrogen interaction with the surface modified TiZr layer, as well as its resistance properties, are discussed.