High Temperature Oxidation Behavior Research Articles

High-temperature oxidation behaviors of Co-free Cr30Fe30Ni30Al5Ti5 dual-phase multi-component alloys with multi-scale nanoprecipitates

In the context of the growing research interest in multi-component alloys (MAs) and their exceptional performance under extreme environments, the high-temperature oxidation resistance and applications of MAs have attracted significant attention in the field of metallic materials. While the cost-effective and mechanical properties of Co-free MAs are of great importance, their oxidation resistance remains insufficiently understood. In this work, we designed multiple heterogeneous structures within a cast dual-phase Cr30Fe30Ni30Al5Ti5 MA by tailoring the Al and Ti ratio, which consists of body-centered-cubic (BCC) grains reinforced by multi-scale nanoprecipitates (i.e., L21, B2, and η phase) and an L12-strengthened face-centered cubic (FCC) skeleton. Isothermal oxidation experiments at 800 °C, 1000 °C, and 1200 °C with varying exposure durations were conducted. The oxidation kinetics at 800 °C and 1000 °C followed a parabolic law, while both low weight increment and oxidation rate confirm remarkable oxidation resistance. At 800 °C, the oxides mainly consist of Cr2O3 and Al2O3, while are dominated by (TiO2 + Cr2O3) and the mixed oxides of Al2O3, TiO2, and Ti2O above 1000 °C. Importantly, the inability to form a continuous Al2O3 oxide scale at higher temperatures led to a deterioration in oxidation resistance. These findings offer valuable insights into underlying mechanisms contributing to oxidation resistance for Co-free MAs.

Oxidation Behaviour of Fe-28Al-5Si at.% Alloyed with Ti and Mo

AbstractThe high-temperature oxidation behaviour of Fe-28Al-5Si, Fe-28Al-5Si-2Mo and Fe-28Al-5Si-2Ti (in at.%) was investigated. Cyclic oxidation tests of iron aluminides were performed at 900°C and 1100°C. The oxidation kinetics and oxidation behaviour (by measuring of total weight gain, etc.) were described. The structure of the alloys’ surfaces after oxidation, as well as the composition and morphology of oxide layers, was analysed by optical microscopy, scanning electron microscopy, SEM–EDS and X-ray diffraction. The beneficial effect of alloying with titanium or molybdenum on the oxidation resistance of Fe-Al-Si-based alloys was observed at temperatures of 900°C and 1100°C. Titanium and molybdenum suppress the formation of eutectic regions of the secondary phase in the structure, which preferentially oxidize. Therefore, a thin and compact alumina layer (only minor amounts of iron oxides and ZrO2) formed on the surface of Fe-28Al-5Si-2Mo and Fe-28Al-5Si-2Ti at 900°C. These alloys maintain low weight gains even at a temperature of 1100°C. On the other hand, alloy Fe-28Al-5Si contains a high number of eutectics-like areas, which causes ingress of the oxidation (selective oxidation of eutectic areas) and breakaway oxidation is observed at 900°C and 1100°C, respectively.

Short-time high-temperature oxidation behavior of nanocrystalline Ta coating at 850 °C

Short-time high-temperature oxidation behavior of nanocrystalline Ta coating at 850 °C

High Temperature Oxidation Behavior of High Al-Si Alloyed Vermicular Graphite Cast Iron for Internal Combustion Engine’s Hot-End Exhaust Components

High Temperature Oxidation Behavior of High Al-Si Alloyed Vermicular Graphite Cast Iron for Internal Combustion Engine’s Hot-End Exhaust Components

Effects of Zr content on microstructure and properties of 9Cr ferritic/martensitic steel

The effect of the Zr content range in 0.03–0.63 wt% on the microstructure, mechanical properties and high-temperature oxidation behaviors of 9Cr ferritic/martensitic (FM) steels was investigated. The microstructural evolution of steels was studied using Thermo-Calc software, SEM, EBSD and TEM technologies. A full martensite structure was obtained in steels with various Zr contents. The small-sized M23C6 decrease and the larger-sized Zr(C, N) increase with the increasing Zr content, which leads to the increase of martensitic lath width and martensitic block size. The proper Zr content can enhance the oxidation resistance of steel, but Zr addition will reduce the mechanical properties. The decrease in strength and hardness can be ascribed to the reduction of precipitation strengthening and gain size strengthening. The increase in Zr content promotes the formation of Zr oxides, which reduces the formation of MnCr2O4 oxides and Cr2O3 oxides, and finally improves the oxidation resistance of steels.

Effect of Al content on the corrosion behavior and mechanism of AlxCoCrFeNi high-entropy alloys

Al addition is known to improve the tensile strength and high-temperature oxidation behavior of the AlxCoCrFeNi high-entropy alloy (HEA). However, the corrosion behavior and mechanisms associated with these HEAs remain unclear. The corrosion resistance of structural materials is as important as their mechanical properties. In this study, AlxCoCrFeNi HEAs with different molar ratios of Al (x = 0.0, 0.5, 1.0, and 1.5) and various crystal structures (FCC, FCC + BCC, and BCC phases) were prepared, and their corrosion behavior and mechanisms were studied, which revealed a competitive relationship between the Al and Cr passivation films. The thickness of the Al passivation film increased with increasing Al content, which was found to be the main reason for the decrease in the corrosion resistance of the AlxCoCrFeNi HEAs. The corrosion type of the AlxCoCrFeNi HEA changed from pitting corrosion to selective corrosion with increasing Al content, and the corroded elements changed from (Co, Cr, Fe, and Ni) to (Al and Ni) and then (Al, Ni, and Co). Accordingly, the corrosion mechanisms associated with the AlxCoCrFeNi HEAs were elucidated.

The Effect of Refined Coherent Grain Boundaries on High-Temperature Oxidation Behavior of TiAl-Based Alloys through Cyclic Heat Treatment

The grain size of the full lamellae TiAl-based alloy changes from ~400 μm to ~40 μm through the precipitation of metastable structures by cyclic heat treatment. Based on this, two kinds of variant selection processes—coherent metastable γ variants precipitated during the air-cooling process and αs variants precipitated during the holding at a single α phase region process—are identified to promote the formation of refined Type I and Type II coherent grain boundaries. The oxidation tests at 1000 °C for 100 h show that the formation of refined coherent grain boundaries can greatly improve oxidation resistance by inducing the continuous multi-layer protective barrier consisting of (Ti, (Nb, Ta))O2, TiN, and Al(Nb,Ta)2. This protective barrier inhibits the inward diffusion of oxygen and nitrogen.

High-temperature oxidation behavior of TA15 aerospace titanium alloy at 500 °C and 800 °C

This study investigates the high-temperature oxidation behavior and performance of TA15 Ti alloy subjected to 500 and 800 °C service conditions. The oxidation process, microstructural evolution, mechanical property changes, and comprehensive performance were analyzed. At 500 °C, the alloy developed a distinctive blue-colored surface primarily composed of Ti6O, indicating a slow growth rate of the oxide layer. In contrast, the 800 °C condition led to severe oxidation with notable TiO2 and Al2O3 phases and extensive peeling of the oxidation layer. Microstructural analysis revealed that at 500 °C, there was minimal surface oxidation, and the microstructure showed a shallow heat-affected zone. At 800 °C, repeated oxidation and peeling cycles resulted in grain growth and a significant decrease in the β-phase proportion. Mechanical property assessments indicated an increase in micro Vickers hardness at both temperatures, with the 800 °C sample exhibiting higher values. However, tensile strength decreased significantly at 800 °C due to the severe oxidation layer peeling, reducing the effective thickness during tensile testing. In summary, TA15 demonstrated good high-temperature service performance at 500 °C, while at 800 °C, severe oxidation and peeling adversely affected the overall performance. This research provides insights into the differential high-temperature behavior of TA15, crucial for applications in elevated temperature environments.

Microstructure evolution during oxidation of quinary Ti3(AlSiSn)C2 at high temperatures and induced probable performance

Quinary Ti3Al0.6Si0.2Sn0.2C2 and Ti3Al0.5Si0.4Sn0.1C2 solid solution bulks were synthesized via hot-pressing process. High temperature oxidation behaviors were then investigated over a temperature range of 800–1200 °C. The weight gain per surface area and oxidation layer thickness were measured to study the oxidation kinetics. The as-synthesized compounds with varying solid solution ingredients exhibited comparable oxidation kinetics which fitted a parabolic kinetic better with the oxidation duration of 0–20 h, while it appeared to get more complicated after prolonging the oxidation time. The microstructure evolution and phase compositions of the oxide scales during breakaway oxidation were characterized to illuminate the oxidation mechanism. The oxidation layers exhibited a multi-layer structure resulting from the disparities between the diffusion and migration energies of the multi-elements. Anticipated performance induced by high temperature oxidation was further explored through investigation on the crack self-healing and tribological optimization capacities. It was revealed that cracks could be filled by predominant TiO2 and Al2O3 with a high efficiency at 1000 °C during annealing in air. At 800 °C, Ti3Al0.6Si0.2Sn0.2C2 exhibited self-lubricating properties that was attributed to the formation of smoothing tribo-oxide films, as demonstrated by the increasing oxygen content of the friction surface during sliding.

High temperature oxidation behaviors of TaCrTiW and TaCrTiZrW alloy coatings

The high-temperature oxidation behaviors of a series of refractory high entropy alloys TaCrTiW and TaCrTiZrW alloy coatings at 1073 K in air were studied. A complex protective oxide layer consisting of Cr2O3, TiO2, and CrTaO4 oxides was generated on the alloys surface. Among the TaCrTiW alloy coatings, the presence of TiO2 inhibited the generation of unfavorable oxides and promoted the generation of CrTaO4. The Ta41.7Cr50.3Ti4.5Zr1.6W1.9 exhibits excellent oxidation resistance. The addition of Zr not only accelerated the initial oxide formation but also promoted the rapid formation of Cr2O3.

Effect of the incorporating of refractory NbC precipitates in intermetallic iron-aluminide coatings on corrosion and high-temperature oxidation behavior

This study aims to investigate the effects of growing niobium carbide (NbC) particles into intermetallic iron-aluminide (FeAl) coatings on ductile cast iron (SGI) by thermo-reactive diffusion technique (TRD). The study compares the corrosion and oxidation behavior of the FeAl-NbC coatings with SGI, FeAl, and NbC coatings. Corrosion tests were conducted through polarization tests in a 3.5 wt% NaCl solution, while oxidation tests were performed at 900 °C for 4, 16, and 64 h. Before and after corrosion and oxidation tests, the coatings were examined using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The findings show that FeAl coatings with NbC particles had lower graphite nodules, porosity, and surface roughness values compared to FeAl coatings. FeAl-NbC composite coatings provided better corrosion and oxidation resistance compared to untreated SGI, FeAl, and NbC coatings. The results of the comparative analysis of FeAl-NbC, FeAl, NbC, and untreated SGI specimens indicate that corrosion resistance in a 3.5 wt% NaCl solution and oxidation resistance at 900 °C followed the order FeAl-NbC > FeAl > NbC > SGI.

Alloying on the high-temperature oxidation behavior of Nb-Ti-Si-based alloy additively manufactured by laser directed energy deposition

Nb-Si-based alloys have important application prospects in the new generation of high-thrust-to-weight ratio aero-engines hot-end components. Understanding how alloying affects the microstructure and oxidation resistance of Nb-Si-based alloys is crucial for their applications. In this work, the effects of Zr, Cr and Mo on the microstructure and high-temperature oxidation resistance of Nb-23Ti-14Si-based alloys prepared by laser directed energy deposition (LDED) were investigated. Results showed that the oxidation resistance at 1250 °C of as-deposited Nb-23Ti-14Si-based alloys enhanced by Zr, Cr and Mo alloying, of these, Cr is the most significant, followed by Zr and Mo. The oxide film of Nb-23Ti-14Si-based alloys have three distinct oxide layer: the inner, middle, and outer oxide layer. The formation of SiO2 layer in the Nb-23Ti-14Si-based alloys' outer oxide layer when Zr and Cr alloying, respectively. Furthermore, following oxidation at 1250 °C for 20 h, and the weight gain per unit area is around 32.52 mg/cm2, and the creation of CrNbO4 layer when Cr content is up to 10 at.%.

Exploring the Influence of Nanocrystalline Structure and Aluminum Content on High-Temperature Oxidation Behavior of Fe-Cr-Al Alloys.

The present study examines the high-temperature (500-800 °C) oxidation behavior of Fe-10Cr-(3,5) Al alloys and studies the effect of nanocrystalline structure and Al content on their resistance to oxidation. The nanocrystalline (NC) alloy powder was synthesized via planetary ball milling. The prepared NC alloy powder was consolidated using spark plasma sintering to form NC alloys. Subsequently, an annealing of the NC alloys was performed to transform them into microcrystalline (MC) alloys. It was observed that the NC alloys exhibit superior resistance to oxidation compared to their MC counterparts at high temperatures. The superior resistance to oxidation of the NC alloys is attributed to their considerably finer grain size, which enhances the diffusion of those elements to the metal-oxide interface that forms the protective oxide layer. Conversely, the coarser grain size in MC alloys limits the diffusion of the oxide-forming components. Furthermore, the Fe-10Cr-5Al alloy showed greater resistance to oxidation than the Fe-10Cr-3Al alloy.

Self-propagating high-temperature synthesis of AlxCoCrFeNiMoy high-entropy alloys: thermochemical modelling, microstructural evaluation and high temperature oxidation behaviour

In this study, the feasibility of the synthesis of AlxCoCrFeNiMoy (0.5 < x < 3, y = 0.5,1) alloys via cost and energy efficient thermochemical modelling assisted (FactSage™) aluminothermic self-propagating high-temperature synthesis (SHS) method was investigated. In addition, selected SHS alloys were also suction-casted into a bar shape by using a vacuum arc melter and the microstructural changes and oxidation behaviour of selected alloys were investigated. The characterization results demonstrated that AlxCoCrFeNiMoy (0.5 < x < 3, y = 0.5,1) master alloys can be successfully synthesized via thermochemical modelling assisted SHS method with a substantial composition control. The microstructures of the SHS alloys were found to comprise of the FCC-A1, BCC (A2, B2) and σ phases with varying fractions depending on the composition. Increasing Al content was found to increase the hardness of the alloys from 278 HV to 829 HV for the AlxCoCrFeNiMo0.5 system. For AlxCoCrFeNiMo system, on the other hand, it had an increasing effect from Al0.5 to Al1.0 (from 659 HV to 903 HV) initially and then decreased the hardness to the levels of 773 HV with the further addition of Al. Suction-cast alloys exhibited rather similar microstructures with similar phase constituents and hardness values. As a general trend primer B2 phase fraction was increased due to higher cooling rate. Oxidation studies revealed that the Al3.0Mo0.5 alloy, which has higher B2 content (919 HV), exhibited better oxidation resistance after 100 h of exposure to air at 800 °C. Postulated scaling mechanisms, supported with the CALPHAD simulations and Raman analyses, revealed the formation of non-protective spinel oxides and sublimation of volatile MoOx oxides before the stabilization of a protective M2O3 (M = Al,Cr) layer, especially for the AlCoCrFeNiMo alloy.

Effect of Grain Size on High Temperature Oxidation Behavior of IN792 Superalloy

It is known that Ni-based superalloys possess superior mechanical properties in high-temperature and high-pressure environments. One of the drawbacks of these alloys is their tendency to oxidize at high temperatures. Improving their oxidation properties and obtaining a fundamental understanding of the underlying mechanism of their oxidation behavior are critical for high temperature applications. In this work, we manufactured IN792 Ni-based alloys with two different grain sizes to examine the effect of grain size on oxidation behavior at 850&lt;sup&gt;o&lt;/sup&gt;C and 980&lt;sup&gt;o&lt;/sup&gt;C. The oxidation rate became faster as the grain size became finer, and at 850&lt;sup&gt;o&lt;/sup&gt;C, the oxide layer was composed of external oxides (TiO&lt;sub&gt;2&lt;/sub&gt;/NiO, Ni-Co-Cr-O, Cr&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;), internal oxides (TiTaO&lt;sub&gt;4&lt;/sub&gt;, non-oxidized layer, Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;) and a precipitate-free zone (PFZ). At 980&lt;sup&gt;o&lt;/sup&gt;C, this structure became unstable due to the diffusion of Ni, and in particular, a lot of exfoliation of external oxides occurred in the coarse grain. Regardless of the structure of the oxide layers, the thickness of the PFZ increased significantly in the fine grains with a low  fraction. Compared to the hardness of external Cr-rich oxides of ~500 HV, the hardnesses of the internal oxides consisting of Al-rich and Ni-Al-O were approximately 1000 HV and 1500 HV, respectively. Therefore, the most vulnerable position is expected to be the interfacial boundary between the external oxide and internal oxide, and this resulted in the ease of exfoliation of the external oxide in this location, by exposing the Ni-Al-O oxide to the surface in the coarse grain at 980&lt;sup&gt;o&lt;/sup&gt;C. The current work can be a useful method in the design of Ni-based superalloys by controlling the grain size of the components.

Electrochemical Technique to Characterize the High Temperature Oxidation Behavior of Materials

This work demonstrates an approach using solid state electrochemical cells to study the long-term oxidation of materials at 800 °C. The capability of zirconia-based cells to control the oxygen partial pressure was first evaluated using an empty chamber. For most voltages applied to the pump cell, the steady state sensor voltage matches the pump voltage, leakage rates are low, and response times are short, allowing precise and prompt control over the chamber atmosphere. The technique was validated by measuring the oxidation of niobium and nickel. Niobium was oxidized at pump voltages ranging from 0 mV to +500 mV; decreasing the oxygen partial pressure around the specimen reduces the oxidation rate. Comparing the integrated oxidation rate with the weighed mass gain showed good agreement. Measured oxidation rates for nickel were of order 1 μg h−1, illustrating the sensitivity of this technique. For higher oxidation rates, a depression in oxygen partial pressure was observed around the specimen. Improved control over the oxidation potential was achieved by using a sensor cell to dynamically tune the pump voltage. Rates for both metals are compared to literature reports using other techniques.

Enhancing AISI 321 stainless steel's high-temperature oxidation resistance at 600 °C through surface nanocrystallization and pre-oxidation synergy

This study explores the high-temperature oxidation behavior of AISI 321 austenitic stainless steel (ASS) at 600 °C in an Ar-21vol.%O2 atmosphere, considering nanometer-sized surface grain size and pre-oxidation conditions. After initial solution annealing at 1050 °C, AISI 321 ASS samples were water-quenched for homogenized microstructure (SAed samples). Moreover, the surface nanocrystallization of AISI 321 ASS was performed through high-energy shot peening (SNCed samples), reducing the surface grain size to ~75 ± 5 nm. Pre-oxidation occurred at 400 °C for 150 h in Ar-21%O2 for both SAed and SNCed samples. High-temperature oxidation kinetics was analyzed at 600 °C for 150 h using thermal gravimetric analysis (TGA) on pre-oxidized and non-preoxidized SAed and SNCed samples. FESEM/GDOES and GI-XRD revealed that SNCed samples exhibited improved oxidation resistance, showing no Cr depletion in the subsurface oxide layer up to 100 h, and only minor signs after 150 h. Pre-oxidized SNCed samples demonstrated superior oxidation performance, showing no Cr depletion and subsurface Kirkendall pore formation even after 150 h. These findings are coupled with diffusion relationships, and propose potential mechanisms for enhancing the oxidation behavior of pre-oxidized SNCed AISI 321 stainless steel.

Effect of Ti and C addition on oxidation resistance of FeCoCrNiMn high entropy alloys prepared by powder metallurgy

Purpose The purpose of this paper is to study the high temperature oxidation behavior of Ti and C-added FeCoCrNiMn high entropy alloys (HEAs). Design/methodology/approach Cyclic oxidation method was used to obtain the oxidation kinetic profile and oxidation rate. The microstructures of the surface and cross section of the samples after oxidation were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Findings The results show that the microstructure of the alloy mainly consisted of FCC (Face-centered Cubic Structure) main phase and carbides (M7C3, M23C6 and TiC). With the increase of Ti and C content, the microhardness, strength and oxidation resistance of the alloy were effectively improved. After oxidation at a constant temperature of 800 °C for 100 h, the preferential oxidation of chromium in the chromium carbide determined the early formation of dense chromium oxide layers compared to the HEAs substrate, resulting in the optimal oxidation resistance of the TC30 alloy. Originality/value More precipitated CrC can preferentially oxidize and rapidly form a dense Cr2O3 layer early in the oxidation, which will slow down the further oxidation of the alloy.

High temperature oxidation behavior of MoCoB metallic glass

The oxidation behavior of a Mo51Co34B15 metallic glass was investigated at 873–973 K in dry air. The oxidation kinetics generally followed a parabolic-rate law, which indicated the rate-controlling step in the oxidation process is diffusion, and the parabolic-rate constants increased with increasing temperature, showing the oxidation rate is closely related to temperature. The thinner oxide layer was mainly composed of CoMoO4, MoO3, CoO, B2O3, and MoB, while the CoMoO4 and B2O3 oxides resulted in a lower oxidation rate, and the presence of MoB also suggested that small amounts of crystallization were taking place beneath the inner layer.

High temperature oxidation behavior of CoCrFeNiMo0.2 high-entropy alloy coatings produced by laser cladding

The oxidation behavior of CoCrFeNiMo0.2 high-entropy alloy laser cladding coatings at 700°C and 900°C was investigated. The oxidation kinetics of the alloys at all temperatures followed a parabolic behavior, with the oxidation rates increasing significantly with increasing temperature. The alloy exhibits excellent oxidation resistance at 700 °C. Compared with the original alloy structure, the segregation of Mo element in the alloy is more serious after high-temperature treatment. Compared with 700 °C, the oxidation degree of the alloy is more intense at 900 °C. The reaction between iron and chromium oxides forms a chromite layer, and the rapid diffusion of iron ions in the layer forms an outer layer of iron oxides. As the oxidation proceeds, the oxide film is separated from the metal, and the chromium oxide layer grows between the spinel layer and the metal. The thermodynamics of the reaction was calculated, the oxidation mechanism of the alloy was explored, and a high-temperature model of the alloy was developed. This study expands the potential applications of high entropy alloys in surface engineering.