Corrosion and Oxidation Behavior of Ti-Based Amorphous and Nanocrystalline Alloys

2011 ◽  
Vol 171 ◽  
pp. 51-66 ◽  
Author(s):  
S.K. Sharma
Keyword(s):  
Oxidation Resistance ◽  
Amorphous Alloys ◽  
Oxidation Behavior ◽  
Aqueous Media ◽  
Nanocrystalline Alloys ◽  
Structural Defects ◽  
Nanocrystalline Phase ◽  
Nanocrystalline State ◽  
Chemical Homogeneity ◽  
Corrosion And Oxidation

Amorphous alloys, in general, exhibit superior mechanical and chemical properties as compared to their crystalline counterparts, which is attributed to their chemical homogeneity and to the absence of crystal-like structural defects. Nanocrystalline and fully crystallized forms of these alloys can be easily obtained by a suitable thermal annealing treatment. It is important to have the knowledge of corrosion/oxidation behavior of amorphous and nanocrystalline alloys for various possible applications. In contrast to many investigations on corrosion and oxidation behavior of amorphous alloys reported in the literature, only limited studies have been carried out on comparison of corrosion/oxidation behavior of amorphous and nanocrystalline states of the same alloy. With this motivation potentiodynamic polarization studies were carried out on amorphous and nanocrystalline states of the alloy Ti60Ni40 in several aqueous media at room temperature. The oxidation in air was also investigated in the temperature range 2800C-3800C using a thermogravimetric analyzer. It was found from these investigations that nanocrystalline state exhibits the maximum corrosion/oxidation resistance in comparison to amorphous and crystalline states. The better corrosion/oxidation resistance of nanocrystalline state can be explained in terms of the nature of the nanocrystalline phase/phases and the size of the crystallites. The results of the present study are supported by other similar studies reported in the literature. A short review on comparison of corrosion/oxidation behaviour of amorphous and nanocrystalline Ti-based alloy is also presented in the paper.

A Comparative Study of Corrosion Behaviour of Amorphous and Nanocrystalline Ti60Ni40 in 0.5 M H2SO4 and 0.5 M HNO3 Aqueous Media

2009 ◽  
Vol 67 ◽  
pp. 179-184 ◽  
Author(s):  
Shubhra Mathur ◽  
Rishi Vyas ◽  
S.N. Dolia ◽  
Kanu Sachdev ◽  
S.K. Sharma
Keyword(s):  
Corrosion Behaviour ◽  
Aqueous Media ◽  
Amorphous State ◽  
Side Surface ◽  
Corrosion Current ◽  
Nanocrystalline Phase ◽  
X Ray Diffraction ◽  
Nanocrystalline State ◽  
X Ray ◽  
Corrosion Studies

Corrosion studies were carried out using potentiodynamic polarization method on amorphous, nanocrystalline and crystalline states of the alloy Ti60Ni40 in 0.5 M H2SO4 and 0.5 M HNO3 aqueous media at room temperature. The nanocrystalline state of Ti60Ni40 was obtained by removing about 10 μm from the air side surface (crystalline state) by polishing. The presence of nanocrystalline phase was confirmed by X-ray diffraction (XRD). It was found from polarization results that the corrosion current density was higher in the amorphous state than in the nanocrystalline state in both 0.5 M H2SO4 and 0.5 M HNO3 aqueous media. These results are corroborated by the weight loss studies which were carried out in both of these media. Results are discussed in the paper in the light of data reported in the literature on similar type of alloys.

scholarly journals Oxidation behavior of non-stoichiometric (Zr,Hf,Ti)Cx carbide solid solution powders in air

2021 ◽  
Author(s):  
Huilin Lun ◽  
Yi Zeng ◽  
Xiang Xiong ◽  
Ziming Ye ◽  
Zhongwei Zhang ◽  
...  
Keyword(s):  
Solid Solution ◽  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Group Iv ◽  
Hypersonic Vehicles ◽  
Metal Carbides ◽  
Initial Oxidation ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Kinetics Of

AbstractMulti-component solid solutions with non-stoichiometric compositions are characteristics of ultra-high temperature carbides as promising materials for hypersonic vehicles. However, for group IV transition-metal carbides, the oxidation behavior of multi-component non-stoichiometric (Zr,Hf,Ti)Cx carbide solid solution has not been clarified yet. The present work fabricated four kinds of (Zr,Hf,Ti)Cx carbide solid solution powders by free-pressureless spark plasma sintering to investigate the oxidation behavior of (Zr,Hf,Ti)Cx in air. The effects of metallic atom composition on oxidation resistance were examined. The results indicate that the oxidation kinetics of (Zr,Hf,Ti)Cx are composition dependent. A high Hf content in (Zr,Hf,Ti)Cx was beneficial to form an amorphous Zr-Hf-Ti-C-O oxycarbide layer as an oxygen barrier to enhance the initial oxidation resistance. Meanwhile, an equiatomic ratio of metallic atoms reduced the growth rate of (Zr,Hf,Ti)O2 oxide, increasing its phase stability at high temperatures, which improved the oxidation activation energy of (Zr, Hf, Ti)Cx.

scholarly journals Rare Earth Elements Enhanced the Oxidation Resistance of Mo-Si-Based Alloys for High Temperature Application: A Review

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1144
Author(s):  
Laihao Yu ◽  
Yingyi Zhang ◽  
Tao Fu ◽  
Jie Wang ◽  
Kunkun Cui ◽  
...  
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
Rare Earth Elements ◽  
Oxidation Resistance ◽  
Oxidation Behavior ◽  
Strengthening Mechanism ◽  
Advanced Materials ◽  
Performance Requirements ◽  
Large Numbers ◽  
The One

Traditional refractory materials such as nickel-based superalloys have been gradually unable to meet the performance requirements of advanced materials. The Mo-Si-based alloy, as a new type of high temperature structural material, has entered the vision of researchers due to its charming high temperature performance characteristics. However, its easy oxidation and even “pesting oxidation” at medium temperatures limit its further applications. In order to solve this problem, researchers have conducted large numbers of experiments and made breakthrough achievements. Based on these research results, the effects of rare earth elements like La, Hf, Ce and Y on the microstructure and oxidation behavior of Mo-Si-based alloys were systematically reviewed in the current work. Meanwhile, this paper also provided an analysis about the strengthening mechanism of rare earth elements on the oxidation behavior for Mo-Si-based alloys after discussing the oxidation process. It is shown that adding rare earth elements, on the one hand, can optimize the microstructure of the alloy, thus promoting the rapid formation of protective SiO2 scale. On the other hand, it can act as a diffusion barrier by producing stable rare earth oxides or additional protective films, which significantly enhances the oxidation resistance of the alloy. Furthermore, the research focus about the oxidation protection of Mo-Si-based alloys in the future was prospected to expand the application field.

Effects of Yttrium on Cyclic Oxidation Resistance of Co-10Cr-5Al Alloy at 700 °C

2014 ◽  
Vol 528 ◽  
pp. 25-29
Author(s):  
Ling Yun Bai ◽  
Xian Chao Xu ◽  
Jun Huai Xiang ◽  
Yun Xiang Zheng ◽  
Jun Wang
Keyword(s):  
Oxide Scale ◽  
Oxidation Resistance ◽  
Oxidation Rate ◽  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Adhesive Property ◽  
Complex Mode ◽  
Rate Law ◽  
Parabolic Rate

The cyclic oxidation behavior of Co-10Cr-5Al alloys in atmosphere at 700 °C was investigated. The addition of 0.3 at.% Y changed the oxidation behavior from the approximate parabolic rate law to complex mode. The scale grown on the surface of Co-10Cr-5Al cracked seriously, while the oxide scale the Y doped alloy had better adhesive property. Yttrium doped in the sample promoted the forming of continuous Al2O3layer and decreased the oxidation rate of Co-10Cr-5Al alloys.

Effect of Phase Fraction Ratio Between Al3Mg2 and Mg2Si on the Oxidation Behavior of Al–Mg–Si Alloys

2021 ◽  
Vol 16 (7) ◽  
pp. 1047-1051
Author(s):  
Seong-Ho Ha ◽  
Abdul Wahid Shah ◽  
Bong-Hwan Kim ◽  
Young-Ok Yoon ◽  
Hyun-Kyu Lim ◽  
...  
Keyword(s):  
Oxidation Resistance ◽  
High Temperatures ◽  
Cross Sections ◽  
Oxidation Behavior ◽  
Eutectic Phase ◽  
Mg Alloy ◽  
Phase Fraction ◽  
The Matrix ◽  
Si Content

The effect of the phase fraction ratio between Al3Mg2 and Mg2Si on the oxidation resistance of Al–Mg–Si alloys at high temperatures was investigated. With addition of 1 mass%Si in Al-6 mass%Mg alloy, the as-cast microstructures showed formation of Mg2Si phase by eutectic reactions. With increasing Si content more than 3 mass%, the Mg2Si and Si are formed as eutectic phases with no β-Al3Mg2 phase. In addition, with an increase in the Si content from 3 mass%, significantly refined as-cast microstructures and distribution of extended eutectic phase areas were observed. The oxidized cross-sections of Al-6 mass%Mg and Al-6 mass%Mg-1 mass%Si alloys showed coarse and dark areas, which are considered as oxide clusters, nonuniformly grown into the matrix. However, Al-6 mass%Mg-3 mass%Si and Al-6 mass%Mg-5 mass%Si alloys had no significantly grown oxide clusters on the surfaces. Based on the results, it was concluded that the reduction of the ratio between β-Al3Mg2 and Mg2Si phases can reduce the rapid oxidation of Mg.

scholarly journals Oxidation Resistance of Nanocrystalline Alloys

10.5772/34928 ◽  
2012 ◽  
Author(s):  
Nick Birbilis ◽  
Jianqiang Zhang ◽  
Rajeev Gupt
Keyword(s):  
Oxidation Resistance ◽  
Nanocrystalline Alloys

scholarly journals The Process of Magnetizing FeNbYHfB Bulk Amorphous Alloys in Strong Magnetic Fields

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1367
Author(s):  
Bartłomiej Jeż ◽  
Jerzy Wysłocki ◽  
Simon Walters ◽  
Przemysław Postawa ◽  
Marcin Nabiałek
Keyword(s):  
Magnetic Fields ◽  
Amorphous Alloys ◽  
Magnetization Vector ◽  
Direct Methods ◽  
Structural Defects ◽  
Alloy Sample ◽  
Magnetization Curves ◽  
Magnetization Process ◽  
Strong Magnetic Fields ◽  
Antiferromagnetic Ordering

The structure of amorphous alloys still has not been described satisfactorily due to the lack of direct methods for observing structural defects. The magnetizing process of amorphous alloys is closely related to its disordered structure. The sensitivity of the magnetization vector to any heterogeneity allows indirect assessment of the structure of amorphous ferromagnetic alloys. In strong magnetic fields, the magnetization process involves the rotation of a magnetization vector around point and line defects. Based on analysis of primary magnetization curves, it is possible to identify the type of these defects. This paper presents the results of research into the magnetization process of amorphous alloys that are based on iron, in the areas called the approach to ferromagnetic saturation and the Holstein–Primakoff para-process. The structure of a range of specially produced materials was examined using X-ray diffraction. Primary magnetization curves were measured over the range of 0 to 2 T. The process of magnetizing all of the tested alloys was associated with the presence of linear defects, satisfying the relationship Ddi p < 1H. It was found that the addition of yttrium, at the expense of hafnium, impedes the magnetization process. The alloy with an atomic content of Y = 10% was characterized by the highest saturation magnetization value and the lowest value of the Dspf parameter, which may indicate the occurrence of antiferromagnetic ordering in certain regions of this alloy sample.

An Effective Approach to Improve the Oxidation Resistance of Ti-6Al-4V Alloy by Combination of Phosphorization and Silica Coating

2011 ◽  
Vol 148-149 ◽  
pp. 534-537
Author(s):  
Chun Xiang Gao
Keyword(s):  
Oxidation Resistance ◽  
Cyclic Oxidation ◽  
Oxidation Behavior ◽  
Sol Gel ◽  
Synergetic Effect ◽  
Silica Coating ◽  
Dip Coating ◽  
Sio2 Coating ◽  
Amorphous Sio2 ◽  
Dip Coating Technique

A very effective approach to improve the oxidation resistance of Ti-6Al-4V alloy was proposed. The Ti-6Al-4V alloy was firstly phosphated and then coated by silica using sol-gel dip-coating technique. A duplex layer of TiP2O7 and amorphous silica was synthesized at the alloy surface. The isothermal and cyclic oxidation behavior of the treated alloy with silica coating and the corresponding bare alloy was investigated at 600 oC in static air to investigate the synergetic effect of phosphorization and amorphous SiO2 coating on the oxidation resistance of the alloy. The isothermal and cyclic oxidation resistances of the alloy were greatly improved.

MICROSTRUCTURE EVALUATION OF Fe-BASED AMORPHOUS ALLOYS INVESTIGATED BY DOPPLER BROADENING POSITRON ANNIHILATION TECHNIQUE

2013 ◽  
Vol 27 (19) ◽  
pp. 1341014
Author(s):  
WEI LU ◽  
PING HUANG ◽  
YUXIN WANG ◽  
BIAO YAN
Keyword(s):  
Grain Size ◽  
Positron Annihilation ◽  
Amorphous Alloys ◽  
Annealing Temperature ◽  
Amorphous Matrix ◽  
Nanocrystalline Phase ◽  
Magnetic Alloy ◽  
Type I ◽  
Doppler Broadening ◽  
Average Grain Size

Microstructure of Fe -based amorphous and nanocrystalline soft magnetic alloy has been investigated by X-ray diffraction (XRD), transmission electronic microscopy (TEM) and Doppler broadening positron annihilation technique (PAT). Doppler broadening measurement reveals that amorphous alloys (Finemet, Type I) which can form a nanocrystalline phase have more defects (free volume) than alloys (Metglas, Type II) which cannot form this microstructure. XRD and TEM characterization indicates that the nanocrystallization of amorphous Finemet alloy occurs at 460°C, where nanocrystallites of α- Fe with an average grain size of a few nanometers are formed in an amorphous matrix. With increasing annealing temperature up to 500°C, the average grain size increases up to around 12 nm. During the annealing of Finemet alloy, it has been demonstrated that positron annihilates in quenched-in defect, crystalline nanophase and amorphous-nanocrystalline interfaces. The change of line shape parameter S with annealing temperature in Finemet alloy is mainly due to the structural relaxation, the pre-nucleation of Cu nucleus and the nanocrystallization of α- Fe ( Si ) phase during annealing. This study throws new insights into positron behavior in the nanocrystallization of metallic glasses, especially in the presence of single or multiple nanophases embedded in the amorphous matrix.

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