Enhanced Oxidation Resistance of Pt‐Containing Inconel 718 Alloy through Facilitated Formation of Protective Chromia

Oxidation characteristics of the electron beam surface-treated Alloy 617 in high temperature helium environments

Development of graded composition and microstructure on Inconel 718 by laser surface alloying with Si, Al and ZrB2 for improvement in high temperature oxidation resistance

Evolution of surface chemistry and morphology of oxide scale formed during initial stage oxidation of modified 9Cr–1Mo steel

There has been steady progress in the development of wrought nickel-containing alloys for use in high temperature oxidizing environments. Contributing significantly to this progress is a growing knowledge base on the role of scales in enhancing oxidation resistance. Future improvements in oxidation resistance must build upon this understanding. This paper seeks to survey a portion of the wealth of information regarding scale characteristics of commercial wrought nickel-containing alloys and how scales are influenced by environment and alloy composition. Some suggestions as to the future direction of alloy development with regard to scale optimization and increased oxidation resistance are proposed.

Improvement of oxidation resistance of Nb–Ti–Si based alloys with additions of Al, Cr and B at different temperatures

Surface passivation, a desirable natural consequence during initial oxidation of alloys, is the foundation for functioning of corrosion and oxidation resistant alloys ranging from industrial stainless steel to kitchen utensils. This initial oxidation has been long perceived to vary with crystal facet, however, the underlying mechanism remains elusive. Here, using in situ environmental transmission electron microscopy, we gain atomic details on crystal facet dependent initial oxidation behavior in a model Ni-5Cr alloy. We find the (001) surface shows higher initial oxidation resistance as compared to the (111) surface. We reveal the crystal facet dependent oxidation is related to an interfacial atomic sieving effect, wherein the oxide/metal interface selectively promotes diffusion of certain atomic species. Density functional theory calculations rationalize the oxygen diffusion across Ni(111)/NiO(111) interface, as contrasted with Ni(001)/NiO(111), is enhanced. We unveil that crystal facet with initial fast oxidation rate could conversely switch to a slow steady state oxidation.

Achieving exceptional high-temperature strength and oxidation resistance in an additively manufactured refractory high-entropy alloy via strategic elemental substitutions

Studies of the initial oxidation of Fe-Si alloys by AES, XPS and EELS

Tantalum carbide (TaC) and hafnium carbide (HfC) have some of the highest melting temperatures among the transition metal carbides, borides, and nitrides, making them promising materials for high‐speed flight and high‐temperature structural applications. Solid solutions of TaC and HfC are of particular interest due to their enhanced oxidation resistance compared to pure TaC or HfC. This study looks at the effect of Hf content on the oxidation resistance of TaC–HfC sintered specimens. Five compositions are fabricated into bulk samples using spark plasma sintering (2173 K, 50 MPa, 10 min hold). Oxidation behavior of a subset of the compositions (100 vol% TaC, 80 vol% TaC + 20 vol% HfC, and 50 vol% TaC + 50 vol% HfC) is analyzed using an oxyacetylene torch for 60 s. The TaC–HfC samples exhibit a reduction in the oxide scale thickness and the mass ablation rate with increasing HfC content. The improved oxidation resistance can be attributed to the formation of a Hf6Ta2O17 phase. This phase enhances oxidation resistance by reducing oxygen diffusion and serving as a protective layer for the unoxidized material. The superior oxidation resistance of TaC–HfC samples makes these materials strong contenders for the development of high‐speed flight coatings.

Thermo-mechanically stabilized nanocrystalline (NC) alloys are increasingly valued for their enhanced mechanical strength and high-temperature stability, achieved through thermodynamic and kinetic stabilization methods. However, their fine-grained structure also increases susceptibility to internal oxidation due to higher atomic diffusivity associated with a greater volume fraction of grain boundaries (GBs). By incorporating solutes that form protective oxides, or the so-called thermally growing oxides (TGO), this vulnerability can be mitigated. The TGO scale acts as a diffusion barrier for oxygen that slows down the oxidation kinetics and prevents internal oxidation that impairs the structural integrity of the metal. This review examines advancements in oxidation-resistant NC alloys, focusing on the interplay between grain size and alloy chemistry. We explore how grain refinement influences diffusion coefficients, particularly the enhanced GB diffusion of Ni and Cr in Ni-Cr-based alloys, which improves oxidation resistance in NC variants like Ni-Cr and Cu-Cr compared to coarse-grained counterparts. We also analyze the role of third elements as oxygen scavengers and the impact of reactive elements such as Hf, Zr, and Y in NiAl alloys, which can slow down diffusion through early establishment of protective TGO layers and enhance oxidation resistance. The concomitant effect of grain size refinement, modifications in alloy stoichiometry, and enhanced atomic diffusion is shown to manifest via drastic reductions in oxidative mass gain, and visualization of the stable, protective oxide scales is delivered through characterization techniques such as TEM, SEM, and EDS. A brief overview is provided regarding stress effects and the role of induced stress in driving oxide scale spallation, which can negatively impact oxidation kinetics. Lastly, we propose future research directions aimed at developing micro-structurally stable NC alloys through multi-solute strategies and surface modification techniques, targeting robust materials for high-stress applications with improved oxidation resistance.

The aim of the present study is to investigate the beneficial influence of an yttrium sol–gel coating on a chromia forming alloy (304 stainless steel), in air, at 1000°C. Thermal cyclic experiments were carried out in order to study the influence of the addition of yttriumon the scale adherence. The yttrium sol–gel coating plays a significant role in enhancing oxidation resistance during isothermal oxidation tests, decreasing specimen weight gain and suppressing the initial transient oxidation stage. Yttrium addition appears to promote silicon segregationat the metal/oxide interface. It is then observed that iron containing oxides are not formed. Under thermal cycling conditions, the addition of yttrium also remarkably improves oxide scale adherence.

Laser surface alloying of Ti with Si, Al and Si+Al for an improved oxidation resistance

Coatings play a key role in modern industry, enhancing the performance of materials. The diversity of their applications and constant progress make them a central area of research and development in materials science and engineering. In this manuscript, we examined some recent works of high-entropy coatings deposited by magnetron sputtering. The first section provides details on the magnetron sputtering technique and deposition mechanism. The change of the parameter influences the microstructure and then the properties of the films. High Power Impulse Magnetron Sputtering is sued to increase the compactness of the film. In the second, a spotlight on High-Entropy Films (HEFs) as an emergent-class material is presented and how their oxidation resistance is improved. Particular attention is being paid to studying the effect of some alloying elements, such as nitrogen and silicon, on oxidation resistance improvement. The last section presents potential applications of these coatings, especially the cutting tools, the diffusion barrier, and other industrial uses.

As the size of an electronic element shrinks to nanoscale, trench design of Si strongly influences the performance of related semiconductor devices. By reactive force field molecular dynamics (ReaxFF MD) simulation, the initial stage oxidation on nano-trenched Si(1 0 0) angled 60°, 90°, 120°, 150° under temperatures from 300 K to 1200 K has been studied. Inhomogeneous oxidation at the convex–concave corners of the Si surface was observed. In general, the initial oxidation process on the Si surface was that, firstly, the O atoms ballistically transported into surface, then a high O concentration induced compressive stress at the surface layers, which prevented further oxidation. Compared to the concave corner, the convex one contacted a larger volume of oxygen at the very beginning stage, leading an anisotropic absorption of O atoms. Afterwards, a critical compression was produced at both the convex and concave corners to limit the oxidation. As a result, an inhomogeneous oxide film grew on nano-trenched Si. Meanwhile, due to enhanced O transport and compression relaxation by increasing temperature, the inhomogeneous oxidation was more obvious under 1200 K. These present results explained the observed experimental phenomena on the oxidation of non-planar Si and provided an aspect on the design of nano-trenched electronic components in the semiconductor field.

Effects of laser shock processing on θ-Al2O3 to α-Al2O3 transformation and oxide scale morphology evolution in (γ’+β) two-phase Ni-34Al-0.1Dy alloys