High Temperature Oxidation Behavior Research Articles

High-Temperature Oxidation Behavior of FeCoCrNi+(Cu/Al)-Based High-Entropy Alloys in Humid Air

Previous studies showed some transition metal high-entropy alloy (HEA) compositions can have good oxidation resistance in air up to 800 °C. Four equiatomic HEAs have been developed based on FeCoCrNi with additions of Mn, Cu, Al or Al+Cu. The oxidation behavior of these HEAs was compared in humid (10 vol.% H2O) air at 800 °C for 100–500 h to investigate the influence of water vapor on the oxidation mechanisms. The Cu- and Al-containing alloys exhibited improved oxidation resistance over the Mn composition. For the Cu-containing alloy, a local attack of the Cu-rich phase was observed, which formed an Fe/Ni/Co/Cr spinel that was surrounded by Cr2O3. This oxide was thicker for the humid air atmosphere when compared to dry air, and the transition of the Cu oxide to the spinel was accelerated. The Al-containing HEA formed a thin Al2O3 scale with humidity suppressing AlN formation and forming a smoother oxide layer. The Al+Cu composition had the highest overall oxidation resistance (minimal local attack, no nitridation) and also showed a smooth oxide scale topography under humid air oxidation as opposed to a plate-like, rougher scale under dry air.

High temperature oxidation behaviour of NiCrAlY clad developed on SS-304 through microwave irradiation

The current study investigates the underlying causes of the microstructural features, microhardness and high-temperature oxidation behaviour of the NiCrAlY powder cladded stainless steel (SS-304) substrate. The cladding was performed by utilizing an industrial multimode microwave apparatus, operating at 1.1 kW and 2.45 GHz with a 900 s processing time. The fabricated clad layer unveiled perfect metallurgical integration with the substrate and was noticed to be free from obvious flaws, including cracks or improper bonding at the clad-base material interface. The deposited clad layer revealed an equiaxed dendritic microstructure at the top while a typical columnar dendritic microstructure at the centre. The X-ray diffraction (XRD) examination of the clad sample revealed the existence of intermetallic compounds like γ′-Ni3Al, and Al5Y3O12 in addition to a solid solution of Iron (Fe) and Nickel (Ni) and chromium (Cr) enriched matrix. The microhardness of the clad layer was noticed to be higher than that of the uncladded SS-304 specimen. High-temperature oxidation investigation performed at 900 °C in air revealed weight gain by all the samples (bare and clad) in a parabolic fashion, initially for around 10 cycles of oxidation, beyond which the weight gain is noticed to saturate. The maximum oxidation resistance exhibited by the clad sample was credited with having intensified α-Al2O3 in the surface layer.

Study on the Effect of Niobium on the High Temperature Oxidation Resistance of Ferritic Stainless Steel

More and more cars are installing urea selective catalytic reduction (SCR) systems to solve the problem of exhaust emissions, which often operates at high temperatures in the exhaust system and is prone to failure of the exhaust pipe due to high-temperature oxidation. And niobium containing ferritic stainless steel has been widely used in the manufacturing of automotive exhaust pipes. In order to extend the service life of ferrite stainless steel exhaust pipes, niobium plays a crucial role as an added alloying element. The solid solution and precipitation of niobium in ferritic stainless steel will give ferritic stainless steel more excellent high temperature resistance. The precipitation of Nb can change the organizational structure in steel and refine the grains. However, if the content is not properly controlled, large particles of (Nb, Ti) C will precipitate, which will reduce the high temperature oxidation resistance. In this paper, the high temperature oxidation behavior of two kinds of ferritic stainless steels with different Nb content at 700 °C, 800 °C and 900 °C was studied. The microstructure of the oxide film on the surface of the material, the thickness of the oxide layer on the cross section, the distribution of chemical composition, the existence form and distribution of Nb element were analyzed by SEM, EDS, XRD and TEM. The results show that the higher the niobium content, the better the high temperature oxidation resistance, and the higher the temperature, the more obvious the high temperature oxidation resistance of niobium. This is because the high Nb content steel is easy to precipitate NbN and other Nb-containing precipitates at the grain boundary, which is helpful to the high temperature resistance. In the case of less Nb content, its ability to generate (Nb, Ti) C precipitates and coarsen at high temperatures reduces its high-temperature resistance.

Comparative study on mechanical properties and high temperature oxidation behaviour of Hastelloy X and Inconel 718 fabricated by laser directed energy deposition

The high temperature oxidation resistance is crucial to assure the reliability of nickel-based superalloy parts serving at elevated temperature. Hastelloy X is a solid solution strengthening superalloy featured by decent mechanical properties and excellent high temperature oxidation resistance, having the potential to replace the commonly used nickel-based superalloy Inconel 718 in appropriate high-end manufacturing fields. In this work, a comparative study on mechanical properties and high temperature oxidation behaviour of Hastelloy X and Inconel 718 fabricated by laser directed energy deposition was carried out. Under the same processing parameters, the as-built Hastelloy X consisted of columnar and cellular γ phase with dispersed carbides, but Inconel 718 contained columnar γ phase with dispersed carbides and γ′ phase. At ambient temperature, Hastelloy X showed better ductility but inferior strength and hardness. Additionally, the isothermal oxidation tests at 1000 and 1100 °C demonstrated that the oxidation kinetics curves of both as-built superalloys followed the parabolic law. Hastelloy X owned a better high temperature oxidation resistance, which could be attributed to the uniformly distributed dense Cr2O3 and the relatively slight exfoliation of oxides in the oxide scales.

A new insight into the mechanism of Ce enhancing high temperature oxidation resistance of hot-formed steel

In this paper, the effect of Ce addition on high temperature oxidation behavior of hot-formed steel was studied by high temperature oxidation experiment. The structure and phase composition of surface oxide layer of specimens with different Ce content were systematically analyzed by SEM, EDS, XPS. The results showed that the addition of Ce promoted the formation of a dense oxide layer during the initial oxidation stage, and effectively weaken the oxidation degree of the steel surface. Meanwhile, the Ce2O3 particles segregation in Si–Cr rich phase reduced the concentration of vacancy defects in oxide layer and enhanced the adhesion between oxide layer and substrate. After Ce addition, the surface oxidation resistance of hot-formed steel is significantly improved.

Mechanism of interstitial atoms on oxidation and fracture of niobium‑silicon alloys

To investigate the effect of interstitial atoms on high-temperature oxidation behavior and fracture room-temperature fracture toughness of niobium‑silicon alloys. The Nb-16Si-24Ti-xC-yB (x = 1, 2; y = 5, 10) alloys were prepared by arc melting. Results show that the addition of C and B elements shifts solidification path to hypereutectic direction and promotes the generation of coarse silicide and lamellar Nb5Si3-Nbss eutectic structure. TiB2 appears in 1C10B and 2C10B alloy as primary phase. The KQ value of 1C5B alloy reaches 12.30 MPa·m1/2 and increased by 95.5% compared to Nb-16Si-24Ti alloy. The surfaces of alloys do not generate stable oxide layer which could defense oxidation effectively. However, the increase of silicide and the obstructive effect of interstitial atoms on inward diffusion of O atoms improves the oxidation resistance of 1C10B and 2C10B alloy. The existence of interstitial atoms reduces the internal stress of oxide film and improves the integrity of oxide layers.

Surface oxidation behavior of spark plasma sintered AlCrCuFeMnWx high entropy alloys at an elevated isothermal temperature

The high-temperature surface oxidation behavior of high-entropy alloys (HEAs) with compositions of AlCrCuFeMnWx (x = 0, 0.05, 0.1, and 0.5) was studied at 800 °C as an isothermal temperature for 50 h. The high entropy alloys (HEAs) were synthesized by mechanical alloying (MA) followed by spark plasma sintering (SPS). This study focused on the effect of oxidation resistance properties with different elevated temperatures on the high entropy alloy over the surfaces. The XRD and Raman analysis confirmed the formation of various oxides like Al2O3, Cr2O3, Fe2O3, and CrO2 mainly. The HEAs follow the single-stage parabolic law at 800 °C. To achieve better resistance against the heat, rather than adding more amount of refractory elements. Consequently, AlCrCuFeMnWx HEAs showed excellent oxidation resistance at elevated temperatures in a specific amount of tungsten. Different values of mass gain, loss, and complex oxidation kinetics were observed for the varying W-containing HEAs. These alloys formed inhomogeneous oxide scales possessing different regions with porous oxide layers and some areas revealed thin oxide scales due to the formation of discontinuous Mn, Cr, and Al-rich scales evidence found through the SEM images. It is noted that complicated oxides formed considerably more frequently on the W0 alloy than on other alloys, indicating that the addition of tungsten in the presence of Cr may inhibit the growth of certain types of multiphasic oxides and prevent spallation.

High-temperature oxidation behavior of laser additively manufactured AlCrCoNiSi-based high-entropy alloys at 1100 ℃

High-temperature oxidation behavior of two laser additively manufactured AlCrCoNiSi-based high-entropy alloys (Al10 and Al15) are systematically studied in this work. These two alloys exhibit similar oxidation behaviors involving initial linear kinetics oxidation and subsequent parabolic kinetics oxidation at 1100 ℃. However, Al10 alloy has a superior oxidation resistance than Al15 alloy according to the oxidation rate constant. α-Al2O3 is the predominant phase of the oxide scales grown on both alloys. Cross-sectional views of the scales show that the scales consist of surface equiaxed grains and underlying columnar grains. For all oxidized alloys, a newly-formed fcc layer forms in the subsurface Al-depletion zone due to the preferential oxidation of aluminum. Al10 alloy exhibits a much thicker newly-formed fcc layer than Al15 alloy after the same oxidation time. This work ascribes the superior oxidation resistance of Al10 alloy to its thick newly-formed fcc layer, which suppresses the outward Al diffusion from the substrate to scale-metal interface by increasing the diffusion distance.

A Method Probing High-Temperature Oxidation Behavior of Crystalline Materials.

To date, the oxidation behavior of crystal materials is not fully understood; additional research is needed to understand the oxidation of materials. Herein, density functional theory (DFT) calculations and a 3D kinetic Monte Carlo (KMC) model are used to investigate the infiltration and diffusion behaviors of oxygen atoms within the crystal. Oxygen molecules readily adsorbes on crystal surfaces of the material and rapidly dissociates, verified by both first-principles calculations and energy-dispersive spectrometer (EDS) results. The infiltration ability of oxygen atoms into the inner crystal layers is affected by the surrounding oxygen atom, lattice compactness, and other factors. Energy-barrier calculations show that crystal thin/dense layers have significant effects on the crystal oxidation process, so high-pressure technology is used to investigate this correlation experimentally. KMC calculations and thermogravimetric analyses (TGA) show the infiltration behavior of oxygen atoms in the main crystal plane (211) toward the inner layers has the highest proportion to the actual high-temperature oxidation behavior of the title material. The results of both the KMC calculations and thermal experiments show the material peeled off upon further oxidation, which accelerates oxidation. At the same time, high-pressure treatment increases the oxidation resistance of materials at lower temperatures (<600°C).

Effect of Cu addition on the tribological properties and oxidation behavior of nanomultilayered AlTiN/Cu coatings

As a soft metal, the addition of Cu has an important influence on the high-temperature tribological properties and oxidation behavior of nanomultilayered AlTiN/Cu coatings. At room temperature (RT), due to abrasive wear, the AlTiN coating exhibited a high friction coefficient of 0.97 and low wear resistance. After adding Cu layer, the friction coefficient gradually decreased to 0.59 at 18.4 at.% Cu due to the lubricating effect of soft metal Cu and CuO, and the best wear resistance was achieved at 2.9 at.% Cu. At 800 °C, the oxidation resistance sharply reduced after adding Cu layer, and exhibited oxidation delamination. At low Cu contents (≤4.5 at.%), by the inward diffusion of O, a mixed oxide layer of Al2O3, TiO2, and CuO formed. At 18.4 at.% Cu, by the outward diffusion and oxidation of Cu, double-layer oxides formed, and the top layer of CuO contributed to a low friction coefficient of 0.53, but also caused a reduce in the wear resistance.

The response of 316 L steel manufactured by selective laser melting route to high-temperature oxidation behaviour: The role of microstructure modification

The current work examines the effect of 316 L steel's microstructure, which is modified through varying scanning angles with the sample surface (HNS (0°), INS (45°), and VNS (90°)) in the selective laser melting (SLM) method and through surface mechanical attrition treatment (SMAT), on its high-temperature oxidation behaviour (at 600–800 °C) is investigated. We have obtained a deeper understanding of the steel's oxidation behaviour by applying various characterisation techniques. The SMATed steel has a ∼ 1000 μm thick deformed layer containing a gradient microstructure, and its topmost layer contains fine twins and nanograins (∼30 nm). The hardness of this surface is ∼1.65 times the non-treated steel's hardness. All samples follow a parabolic rate law during oxidation. The VNS sample unveils the slowest oxidation rate amid the non-treated samples. SMAT increases the activation energy of oxidation. The distribution of elements across the oxidised samples' cross-section shows discontinuous Cr spreading within the oxide layer on the non-treated samples; however, the deformed samples show uniform distribution. Unlike non-SMATed samples, a minute decline in Cr and Mn content is observed underneath the oxide layer on the SMATed samples, confirming their enhanced outward diffusion. The oxide layer on SMATed samples has more Cr- and Mn-rich oxides. These oxides occupy the grain boundaries of the oxidised non-SMATed surfaces, where the micro-pores and cracks are present. Conversely, oxidised SMATed surfaces display uniform, defect-free Cr- and Mn-rich oxides with finer grains. Moreover, the SMATed layer remains reasonably stable during high-temperature oxidation (hardness drop ranges between ∼9 and ∼ 30%).

High-Temperature Oxidation and Hot Corrosion Behaviors and Mechanism of One Typical Aero-Engine Material 0Cr18Ni9 by One Novel Superhydrophobic and Oleophobic Ultrafine Dry Powder Extinguishing Agent

High-Temperature Oxidation and Hot Corrosion Behaviors and Mechanism of One Typical Aero-Engine Material 0Cr18Ni9 by One Novel Superhydrophobic and Oleophobic Ultrafine Dry Powder Extinguishing Agent

Evaluating laser surface melting of NiCrAlY-APS coating and its effect on high-temperature oxidation behavior of NiCrAlY/YSZ thermal barrier coating before and after surface melting

This research study was conducted to investigate the laser melting parameters of NiCrAlY-APS coating. High-temperature oxidation was investigated using yttria partially stabilized zirconia (YSZ) ceramic coating. Also, the oxidation behavior of the TBC coating was investigated and studied before to and after laser surface melting of the NiCrAlY coating. Microstructural characterization was done using a scanning electron microscope (SEM), elemental analysis by energy dispersive spectroscopy (EDS), and phase analysis by X-ray diffraction (XRD). Surface melting was then performed in the power range of 150–300 W and scanning speed of 2–6 mm s−1. Surface melting was also conducted on the coating using two strategies: single-pass and multi-pass. The obtained results showed that the average melting depth and thickness reduction were directly related to the laser power, while they had an inverse relation with the laser scanning speed. Furthermore, multi-pass surface melting parameters reduced porosity to less than 0.1 %. Roughness measurements also showed a decrease in the coating's surface hardness after surface melting, as compared to the APS coating. The structure consisted of oriented columnar dendrites after melting the laser. The adhesion strength of the TBC coating and laser surface melting coating was at 41 MPa and 53 MPa, respectively. After 200 h of oxidation in the G1504 sample, the TGO layer's growth was decreased; due to the growth of a single oxide layer, it had better oxidation resistance in comparison to the other sample.

Revealing High-Temperature Oxidation and Tensile Behaviors along with Underlying Mechanisms of a Titanium Alloy with Precipitated Titanium Silicide

Titanium alloys, with their impressive strength relative to their weight, resistance to corrosion, and compatibility with biological systems, have found extensive applications in various industries. In high-temperature environments, especially within the aerospace sector, it is essential to advance titanium alloys that boast enhanced resistance to oxidation and superior mechanical characteristics. This work investigates the oxidation characteristics and mechanical performances at high temperatures of a titanium alloy with titanium silicide particles. Oxidation at temperatures of 600–700 °C over a span of 8–32 h led to the formation of protective oxide layers and moderate oxidation rates. However, accelerated oxidation and oxide spallation occurred after exposed at 800 °C for a period of 16 h, indicating inadequate oxidation resistance over 800 °C. Subsequent tensile tests at 650 °C revealed intricate dislocation patterns in the α-Ti matrix and their strong interaction with interfaces of α-Ti/Ti5Si3, which is indicative of an efficient load transfer between the precipitates and the matrix. Overall, this study offers fresh perspectives on the oxidation kinetics and the deformation processes of titanium alloys with in-situ Ti5Si3 particles at high temperatures. These insights will guide subsequent alloy development endeavors aiming to broaden the use of titanium alloys in increasingly challenging high-temperature settings.

High-temperature oxidation behaviour of a Co-based superalloy fabricated through laser powder bed fusion

This study investigated the oxidation behaviour of a Co-based superalloy fabricated through laser powder bed fusion at 900 ℃. In terms of oxidation products, the results revealed the generation of basic oxides, such as CoO, Al2O3 and TiO2, and Co-containing spinels, such as CoAl2O4 and Co2TiO4. Heat treatment improved oxidation resistance by reducing the parabolic oxidation rate constant from 0.17234 to 0.10032 mg2 cm−4 h−1. γ′ precipitates, twin boundaries and less spallation in the heat-treated sample contributed to this improvement, leading to a superior oxidation resistance in this study than in previously reported Co-Al-W-based alloys.

High temperature oxidation of cold spray Cr-coated accident tolerant zirconium-alloy cladding with Nb diffusion barrier layer

Cr-Nb bilayer coatings on Optimized ZIRLO™ light water reactor (LWR) fuel cladding tubes were developed using cold spray deposition technology to increase the limiting operational temperature (i.e., binary Cr-Zr eutectic temperature, 1332 °C) of Cr-coated Zr-alloy system. The properties of the dual-layered coatings were improved by varying the type of Cr powder and post-annealing of the cold sprayed Nb layer. High temperature oxidation behavior of Cr-Nb-coated cladding at 1200 °C and 1425 °C in flowing steam were compared with those of Cr-coated cladding and uncoated cladding. At 1200 °C, both Cr-coated cladding and Cr-Nb coated cladding exhibited outstanding oxidation resistance and a continuous intermetallic compound layer (1 – 3 μm thickness) of predominantly Zr-Cr and Cr2Nb formed at the Cr/Zr and Cr/Nb interface, respectively. At 1425 °C, the Cr-coated Zr-alloy cladding showed enhanced oxidation due to rapid consumption of Cr coating by interdiffusion and liquid phase formation, and consequent destabilization of the outer protective Cr-oxide layer. However, the Nb diffusion barrier layer between the Cr coating and Zr-alloy substrate prevented the melting and the outer Cr coating provided excellent oxidation resistance. For this bi-layered system, a diffusion layer devoid of intermetallic phases was observed at the Nb/Zr interface due to the miscibility of the two metals. Reaction pathways that include both surface oxidation and interdiffusion effects within the coating-substrate system have been proposed based on experimental results.

High Temperature Oxidation Behavior of Ni-based High Entropy Superalloys

A new class of polycrystalline gamma-prime strengthened superalloys with alloy compositions of (wt%) Ni-20Co-13Cr-6Fe-4Al-3W-2Mo-(4-x)Nb-(x)Ti (x = 0,1,2) were subjected to cyclic oxidation exposures in dry air at 800 °C for 3600 h. The alloys were borderline chromia/alumina formers, showing good oxidation resistance relative to commercially available materials of similar composition. While all alloys formed alumina scales initially, only the alloy with the lowest Ti/Nb ratio retained an alumina scale for the duration of the exposure. Formation of a continuous layer of rutile TiO2 at the alumina/alloy interface is proposed to cause eventual alumina failure for the alloys containing Ti.

High temperature oxidation behavior and oxide film properties of IN718 alloy after heat treatment by hot pressing sintering

The IN718 superalloy was prepared by hot pressing sintering method, and the IN718 alloy blocks under different sintering pressures were obtained. The hot-pressed IN718 superalloy(HPS IN718) prepared by the optimum sintering pressure was treated by solid solution and aging. The high temperature oxidation behavior and the properties of oxide film of HPS IN718 at 850 °C in air were studied. The microstructure of HPS IN718 was characterized by optical microscope(OM), X-ray diffractometer(XRD), scanning electron microscope(SEM), and energy dispersive spectrometer(EDS). The morphology and microstructure of the oxide film of HPS IN718 at 850 °C for different oxidation times were analyzed. The adhesion and wear resistance of the oxide film was tested by an automatic scratch tester and a pin-on-disc friction and wear tester. The results show that the IN718 alloy prepared by sintering pressure 30 MPa has good density, and more uniform structure. The results of the oxidation test show that with the increase in oxidation time, the weight of the sample increases parabolically. The oxidation rate was 3.84 × 10−3 mg/(cm2·h1), which belongs to the complete oxidation resistance level. The oxides gradually aggregate and grow from small particles and clusters in the early stage of oxidation. After 125 h oxidation, the thickness of the oxide layer is 3–4 µm. The outermost layer of the oxide film is composed of TiO2, Fe2Cr2O4, and Fe0.7Cr1.3O3, the subsurface layer is dense Cr2O3, and the inner oxide is Al2O3. As the oxidation time increases, the adhesion between the oxide film and the substrate increases. The surface friction coefficient of the sample is reduced. It is found that after oxidation for 125 h, the adhesion between the oxide film and the substrate is 15 N, the surface friction coefficient is 0.08, the friction coefficient is reduced by 0.37 compared with the substrate, and the wear resistance is the better.

Laser shock peening of AlCoCrCuFeNi high-entropy alloy fabricated by laser powder bed fusion: An enhanced oxidation-resistance mechanism at high-temperature

The high-temperature oxidation behaviors of laser powder bed fusion (LPBF)-fabricated AlCoCrCuFeNi high-entropy alloy (HEA) with and without laser shock peening (LSP) were investigated over different exposure durations and temperatures. Results revealed that LSP converted the surface stress from tensile to compressive, while also inducing grain refinement and high-density dislocations. Under high temperatures, the coupled effects of grain refinement and compressive residual stress resulted in the formation of dense protective oxidation scales, which inhibited the inward diffusion of oxygen. LSP improved the high-temperature oxidation resistance of LPBF-fabricated AlCoCrCuFeNi HEA, and the enhanced oxidation-resistance mechanisms were discussed.

High temperature oxidation behavior of NiCoCrAlFeY high entropy bond coating fabricated by high-speed laser cladding

The low-diluted NiCoCrAlFeY high entropy bond coating is prepared by high-speed laser cladding (HSLC). Investigation shows it exhibits excellent high temperature oxidation resistance and slow TGO (thermally growth oxides) growth rate, for a protective α-Al2O3 layer fast covering its surface. Meanwhile, the bulk-like structure by HSLC process suppress the internal oxidation effectively. The severe lattice distortion of high entropy composition makes high diffusion energy and low diffusion coefficient for Al, leading the Al slowly consumed in the coating. Results confirm the bond coating deposited by HSLC possess a tremendous potential application at elevated temperature.