Structure and properties of titanium and the Ti-6Al-7Nb alloy after isothermal oxidation

Aniołek, Krzysztof

doi:10.1080/02670844.2020.1711631

Cited by 16 publications

(7 citation statements)

References 49 publications

(89 reference statements)

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“…The production of oxide layers by isothermal oxidation enables a significant improvement in the mechanical properties (hardness) of the Ti-6Al-7Nb alloy. As it results from the previous studies presented in [32], the surface hardness of the Ti-6Al-7Nb alloy can be increased even several times and is strictly dependent on the temperature and time parameters of the oxidation process. The most important parameter influencing the increase in hardness of the obtained oxide layers is the oxidation temperature.…”

Section: Introductionsupporting

confidence: 51%

Mechanical Properties, Corrosion Resistance and Bioactivity of Oxide Layers Formed by Isothermal Oxidation of Ti-6Al-7Nb Alloy

et al. 2021

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Titanium and its alloys are among the most promising biomaterials for medical applications. In this work, the isothermal oxidation of Ti-6Al-7Nb biomedical alloy towards improving its mechanical properties, corrosion resistance, and bioactivity has been developed. The oxide layers were formed at 600, 700, and 800 °C for 72 h. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), 3D profilometry, and microindentation test, were used to characterize microstructure, surface geometrical structure, and the hardness of the diphase (α + β) Ti-6Al-7Nb alloy after oxidation, respectively. In vitro corrosion resistance tests were carried out in a saline solution at 37 °C using the open-circuit potential method and potentiodynamic measurements. Electronic properties in the air were studied using the Scanning Kelvin Probe (SKP) technique. The bioactivity test was conducted by soaking the alkali- and heat-treated samples in simulated body fluid for 7 days. The presence of apatite was confirmed using SEM/EDS and Fourier Transform Infrared Spectroscopy (FTIR) studies. The thickness of oxide layers formed increased with the temperature growth from 0.25 to 5.48 µm. It was found that with increasing isothermal oxidation temperature, the surface roughness, hardness, corrosion resistance, and contact potential difference increased. The Ti-6Al-7Nb alloy after oxidation revealed the HAp-forming ability in a biological environment.

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Section: Introductionsupporting

confidence: 51%

Mechanical Properties, Corrosion Resistance and Bioactivity of Oxide Layers Formed by Isothermal Oxidation of Ti-6Al-7Nb Alloy

et al. 2021

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“…They observed activation energies of oxidation between 600 and 700 °C were 276 and 191 kJ/mol -1 , respectively, for an oxidation duration of 72 h. Kumar et al 34 studied the oxidation kinetics of CP Ti alloy and observed 275 kJ/mol -1 activation energy at oxidation temperatures between 500–800 °C (up to 72 h exposure period). Also, Aniołek 35 observed 278 kJ/mol -1 activation energy of CP titanium alloy at oxidation temperatures between 600–800 °C for 72 h oxidation duration. However, 170 kJ/mol -1 activation energy for Ti–6Al–7Nb alloy was found at the same values.…”

Section: Resultsmentioning

confidence: 95%

Effect of oxide layers formed by thermal oxidation on mechanical properties and NaCl-induced hot corrosion behavior of TC21 Ti-alloy

Ahmed

El-Zomor

Ghazala

et al. 2022

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In the current study on TC21 Ti-alloy (6.5Al–3Mo–1.9Nb–2.2Sn–2.2Zr–1.5Cr), the thermal oxidation formed oxide layers that considerably influenced mechanical properties (hardness and wear). TC21 specimens were oxidized at 600, 700, 800, and 900 °C for 5, 20, and 50 h. NaCl-induced hot corrosion testing was carried out on raw (un-oxidized) and oxidized specimens at 600 and 800 °C for 50 h. The cyclic testing was performed at 600 °C for durations of 5, 10, 20, 30, 40, and 50 h. The average thickness of the layer grew with increasing oxidation time and temperature. A thin oxide layer (average 0.16 µm) was generated by oxidation at a temperature of 600 °C for a duration of 5 h, and at 800 °C, a large oxide layer of 10.8 µm thickness was formed. The most significant surface hardness of 1000 ± 150 HV0.05 was produced for the layer oxidized at 900 °C. On the other hand, the lowest hardness of 360 ± 150 HV0.05 was recorded for the raw materials. Best wear resistance had been achieved for specimens oxidized at 800 °C. During NaCl hot corrosion test, the weight loss of the raw specimen was 6.4 mg/cm2 due to the flaking off of the corrosion product. However, for specimens oxidized at 600 °C for 50 h, weight loss after corrosion testing was 0.54 mg/cm2, less than that of the specimen before corrosion. Oxidized specimens at 800 °C exhibited the best mechanical characteristics and corrosion resistance.

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“…The activation energy (Q ox ) for the oxidation of equiaxed TC21 alloy (for 50 h) was determined as 232 kJ mol −1 . The activation energies of Ti-6Al-4 V alloy at oxidation between 600 and 700 °C were 276 and 191 kJ mol −1 , respectively, for 72 h. The activation energies of commercially pure (CP) Ti alloy at oxidation temperatures between 500 and 800 °C were 275 kJ mol −1 for 72 h. The activation energy for Ti–6Al–7Nb was 170 kJ mol −1 19 , 47 , 48 .…”

Section: Resultsmentioning

confidence: 99%

Impact of thermal oxidation parameters on micro-hardness and hot corrosion of Ti-6Al-3Mo-2Nb-2Sn-2Zr-1.5Cr alloy

Ahmed

El-Zomor

Ghazala

et al. 2023

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Protective oxide layers on Ti-6Al-3Mo-2Nb-2Sn-2Zr-1.5Cr (TC21) alloy with equiaxed microstructure considerably influence micro-hardness and hot corrosion resistance. The present work’s thermal oxidation of TC21 alloy was performed at 600, 700, and 800 °C for 5, 20, and 50 h durations. Hot corrosion methods in NaCl and NaCl + Na2SO4 salt media were applied to raw (unoxidized) and oxidized samples at 600 and 800 °C for 50 h. Hot corrosion was conducted at 600 °C for 5 cycles with 10-h steps. The best oxide layer thickness was observed at 800 °C, which increased with increased oxidation time and temperature. The surface hardness of the oxide layer at 800 °C was 900 ± 60 HV0.05 owing to the formation of TiO2 and Al2O3 phases. Raw material hardness was 342 ± 20 HV0.05, increasing threefold due to thermal oxidation. In the case of NaCl, weight loss dominated all samples except at 800 °C for 5 h. In the case of NaCl + Na2SO4, weight gain occurred at 600 and 800 °C for 5 h. Weight loss occurred for the raw samples and those processed at 800 °C for 20 and 50 h, where the oxide layer flaked off. Surface hardness increased upon hot corrosion testing because of the formation of brittle phases, such as TiO2 and Na4Ti5O12. Samples that oxidized at 800 °C for 5 h had the highest hardness and corrosion resistance.

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Structure and properties of titanium and the Ti-6Al-7Nb alloy after isothermal oxidation

Cited by 16 publications

References 49 publications

Mechanical Properties, Corrosion Resistance and Bioactivity of Oxide Layers Formed by Isothermal Oxidation of Ti-6Al-7Nb Alloy

Mechanical Properties, Corrosion Resistance and Bioactivity of Oxide Layers Formed by Isothermal Oxidation of Ti-6Al-7Nb Alloy

Effect of oxide layers formed by thermal oxidation on mechanical properties and NaCl-induced hot corrosion behavior of TC21 Ti-alloy

Impact of thermal oxidation parameters on micro-hardness and hot corrosion of Ti-6Al-3Mo-2Nb-2Sn-2Zr-1.5Cr alloy

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