Nitride Alloys Research Articles

Comparative Analysis over Tribology Characterization of TiAlN and TiAlSiN PVD Coating on Plasma Nitride Alloy 20

The nickel–iron–chromium (alloy 20) is enriching by hybrid surface treatment through plasma nitride (PN) and physical vapor deposition (PVD) process. The plasma nitriding process takes 12 h at 500 °C. Potentiodynamic testing is used to characterize the corrosion performance of the treated material, followed by morphological analysis of the exposed surface; XRD, EDX, SEM, hardness, and tensile testing are used to investigate appropriate coating properties. Plasma nitride and hybrid PVD nickel–iron–chromium alloys exhibit perlite (γ + α′) phases and martensite (γ + α) phases, respectively. The martensite microstructure ensures superior tensile strength and hardness. The pin-on-disc tribometer test proposes to analyze friction and hard-faced behavior in the dry sliding position. The inclusion of Si improves the adherent oxide film, resulting in a low wear rate in TiAlSiN alloy 20. Due to the presence of the passive film, TiAlSiN alloy 20 exposes the most passive region to attain better corrosion resistance.Graphical Abstract

Characterization of vein-like structures formed in nitrided layers during plasma nitriding of 8Cr4Mo4V steel

In this study, nitrided 8Cr4Mo4V was characterized, using optical microscopy, scanning electron microscopy, transmission electron microscopy (TEM), atom probe tomography (APT), electron probe microanalysis, and Thermo-Calc software, to study the vein-like structures formed during plasma nitriding. The structures existed in a certain zone in the nitrided layers, namely the posterior end of the N-content plateau and the anterior end of the N-content rapid-decline zones. The structures disappeared in the topmost surface layer with increasing nitriding time. For the first time, APT was used to observe these structures. Together, the APT and TEM images revealed that the main components of the structures were Fe3C and alloy nitrides. The structures and matrix were related through the (220) Fe3C//(110)α-Fe, [110] Fe3C//[001]α-Fe orientations. The appearance and disappearance of the structures were closely related to the C and N contents. In the alloy carbides, N replaced C to form alloy carbonitrides and released C and Fe to form Fe3C which appeared as the vein-like structures. In the topmost surface of the nitrided layers, the C content decreased because of decarburization. The Fe3C and alloy carbides were transformed into ferrite and alloy nitrides, and the structures disappeared.

Research on the Effect of Substrate Bias on Properties of Sputtered AlCrNbSiTiV High Entropy Alloy Nitride Films

Research on the Effect of Substrate Bias on Properties of Sputtered AlCrNbSiTiV High Entropy Alloy Nitride Films

Mechanical properties and high temperature oxidation resistance of (AlCrTiV)N coatings synthesized by cathodic arc deposition

High entropy alloy nitrides (AlCrTiV)N coatings were deposited by cathodic arc evaporation at various deposition bias and temperature. The mechanical properties of the as-deposited coatings and their oxidation resistance after annealing at various temperatures were analysed. X-ray analyses show in all coatings a FCC structure with a (111) preferred orientation up to 750 °C. Up to 600 °C, no oxygen penetration is measured in the films while at 800 °C, critical spalling occurs for all samples. The coating deposited at a temperature of 300 °C and negative bias of 100 V exhibits the most interesting compromise in both oxidation resistance and mechanical performances with a hardness of 40 GPa, a friction coefficient of 0.44 and a wear rate of 5.8 · 10−7 mm3·N−1·m−1. Annealing in air at 600 °C for 2h reduces the wear rate to 2.1 · 10−7 mm3·N−1·m−1 and the surface hardness to 17 GPa. Although annealing forms a thin oxide layer that reduces the hardness on the surface of the coating, it also averages the hardness inside the film to 33 GPa regardless of the deposition bias.

Improved crystallinity of GaP-based dilute nitride alloys by proton/electron irradiation and rapid thermal annealing

This study presents the positive effects of proton/electron irradiation on the crystallinity of GaP-based dilute nitride alloys. It is found that proton/electron irradiation followed by rapid thermal annealing enhances the PL peak intensity of GaPN alloys, whereas major photovoltaic III–V materials such as GaAs and InGaP generally degrade their crystal quality by irradiation damage. Atomic force microscopy and transmission electron microscopy reveal no degradation of structural defects. GaAsPN solar cell test devices are then fabricated. Results show that the conversion efficiency increases by proton/electron irradiation, which is mainly caused by an increase in the short-circuit current.

Effect of plasma nitriding process on the fatigue and high temperature corrosion resistance of Inconel 740H nickel alloy

The paper presents a comparison of microhardness, fatigue and high temperature corrosion of Inconel 740H nickel alloy in its as-received state and the same material with nitrided surface layers. The nitrided layers were produced using traditional glow discharge nitriding (specimens nitriding on the cathode potential) and an active screen (specimens nitriding at the plasma potential). A microstructure of the layers was characterized through the scanning electron microscopy, X-ray energy dispersive spectroscopy and X-ray diffraction analysis. Mechanical properties of the nitrided Inconel 740H alloy were examined using microhardness measurements and standard fatigue tests. It was found that Inconel 740H with a nitrided surface exhibited an improved fatigue response of 50 MPa in the whole range of stress amplitudes from 350 to 650 MPa and almost 325% increase of hardness for plasma modified surface and 250% for cathode modified surface. Additionally, the application of cathode nitriding enhanced the corrosion resistance of the alloy in question and effectively protected it against a high temperature oxidation.

Impact of Band Anticrossing on Band-to-Band Tunneling in Highly Mismatched Semiconductor Alloys

We theoretically analyze band-to-band tunneling (BTBT) in highly mismatched, narrow-gap dilute nitride and bismide alloys, and quantify the impact of the $\mathrm{N}$- or $\mathrm{Bi}$-induced perturbation of the band structure---due to band anticrossing (BAC) with localized impurity states---on the electric-field-dependent BTBT generation rate. For this class of semiconductors, the assumptions underpinning the widely employed Kane model of BTBT break down, due to strong band-edge nonparabolicity resulting from BAC interactions. Via numerical calculations based on the Wentzel-Kramers-Brillouin approximation we demonstrate that BAC leads, at fixed band gap, to reduced (increased) BTBT current at low (high) applied electric field compared to that in a conventional ${\mathrm{In}\mathrm{As}}_{1\ensuremath{-}x}{\mathrm{Sb}}_{x}$ alloy. Our analysis reveals that BTBT in ${\mathrm{In}\mathrm{N}}_{x}{\mathrm{As}}_{1\ensuremath{-}x}$ and ${\mathrm{In}\mathrm{As}}_{1\ensuremath{-}x}{\mathrm{Bi}}_{x}$ is governed by a field-dependent competition between the impact of $\mathrm{N}$ ($\mathrm{Bi}$) incorporation on (i) the dispersion of the evanescent Bloch band linking the valence and conduction band edges, which dominates at low field strengths, and (ii) the conduction- (valence-) band-edge density of states, which dominates at high field strengths. The implications of our results for applications in long-wavelength avalanche photodiodes (APDs) and tunneling field-effect transistors (TFETs) are discussed. For APDs, we describe that leakage currents in ideal dilute nitride and bismide devices are likely comparable to those in devices based on conventional III-V materials, but that the expected reduction of the hole impact ionization rate in ${\mathrm{In}\mathrm{As}}_{1\ensuremath{-}x}{\mathrm{Bi}}_{x}$ is promising from the perspective of obtaining low excess noise factor. For TFETs, we describe that $\mathrm{Bi}$ incorporation provides the potential to obtain both reduced subthreshold swing and increased on-state current, making ${\mathrm{In}\mathrm{As}}_{1\ensuremath{-}x}{\mathrm{Bi}}_{x}$ of interest for the development of low-power, high-speed devices.

Evaluation of the Ti6Al4V Alloy Plasma Nitride for Orthopedic Implants: in Vitro Biocompatibility Study in Simulated Body Fluid

In view of this work, plasma nitriding was executed on Ti-6Al-4V and the effect of nitriding by using glow discharge with 2 mbar of Ar+N2 gas on corrosion resistance with different nitriding time and studied. The structure properties and the external appearance for alloys were performed with x-ray diffraction and optical microscopic. The investigation of XRD indicates the Ti alloys are polycrystalline with a cubic type (bcc). When the external appearance of the surface indicates was of β+α structure which have been better technical properties on biomedical application. The biocompatibility investigation of nitride alloys in vitro medium containing human body fluid: we showed a layer of hydroxyapatite HAP which might be considered in good biocompatible ceramic with the expected ability for chemical bonding with bone.

Duplex Aging and Gas Nitriding Process as a Method of Surface Modification of Titanium Alloys for Aircraft Applications

This study discusses the effect of a duplex aging + nitriding process on the wear resistance of an aged double-phase titanium alloy, BT22. Nitriding was applied simultaneously with the heat treatment of the alloy, which is advantageous over the conventional heat and surface treatment methods applied to titanium alloys. According to the results, the thickness of the case depth of the nitrided samples was 40–50 μm. Moreover, nitrogen was uniformly dispersed in the substrate, which was indicated by the hardness tests. The average microhardness of the substrate material was 300 HV0.01, while the hardness of the top layer was 1190 HV0.01, which is an almost four-fold increase. The applied duplex treatment substantially affected the wear performance of the tested alloy. For the untreated alloy, the maximum coefficient of friction was 0.8, while in the surface-modified sample, the maximum fluctuations reached 0.6. The abrasive wear process was dominant in the nitrided samples, while delamination and adhesive wear were observed for the untreated specimens. The nitrided alloy exhibited double the wear resistance of the untreated samples. The proposed treatment does not require additional time or energy consumption, providing a substantial technological advantage over conventional methods. Though the alpha case reduces the mechanical performance of titanium, the nitriding of only the component sections intended to withstand friction will have a positive effect.

Pravci razvoja i primene plazma nitriranja u industriji

This paper presents a discussion of the results of previous research of the effects of surface modification of structural materials and tool steels using plasma nitriding (PN) in order to improve their mechanical, tribological and corrosion behavior. The paper discusses the current status and future directions in the application of PN on various wearing components that are exposed to high loads, stresses and frequent temperature changes. The paper provides an overview of the relevant literature whose results show the most favorable or optimal parameters of the PN process aimed at achieving the best performance in terms of wear and corrosion resistance and hardness increase for the various materials considered. Systematization of literature data about research of the impact of low-temperature PN on stainless steels has placed emphasis on those process mechanisms that achieve benefits for surface layers without creating negative side effects in the form of loss of corrosion resistance. The strengthening of hot forging dies is considered through the reasons and problems that cause the need for the application of PN, and then paper focuses on the role of PN in achieving the tribological properties required to extend the service life of the die. Publications in which the nitriding of titanium alloys is investigated through the reduction of wear, increase of bearing capacity and microhardness depending on the input parameters of the process, ie the optimal parameters applied in order to obtain the best performance characteristics are cited. The application of PN to aluminum and its alloys is discussed, as well as the conditions of testing and the achieved improvements.

Tribological characteristics of samples made from titanium alloy VT5 nitrided in plasma glow discharge

The effect of nitriding of VT5 alloy (3.7115) in the plasma of a glow discharge excited in a hollow cathode on its tribological characteristics in pairs with different materials in jet fuel TS-1 and under dry sliding conditions has been studied. For research and tribological tests, samples of VT5 alloy were nitrided in the plasma of a glow discharge excited in a hollow cathode at a temperature of 975 ± 15 °C and a pressure of 58 ± 2 Pa in a nitrogen-argon gas mixture with a nitrogen content of 78 vol. %. Tribological tests were performed on a friction machine 2070 SMT-1 according to the scheme "cube-roller". Tests under conditions of sliding with jet fuel TS-1 were performed at a load of 200 N. The sliding speed during the tests was 1.3 m/s, and the test time was 75 s. The test under dry sliding conditions was carried out at a load of 100 N and a sliding speed of 0.785 m/s. The test time was 30 minutes. It is shown that the nitrided VT5 alloy in friction pairs with several materials has rather low wear values (≤ 2.26 × 10–6 mm3/Nm), as well as a coefficient of friction at the level of 0.08 to 0.12.

Investigation of the friction and wear properties of nitrided 7075-T6 aluminum alloy under vacuum and ambient air

Investigation of the friction and wear properties of nitrided 7075-T6 aluminum alloy under vacuum and ambient air

Nitriding during Powder Production and Study of the Structure of EP741NP Alloy Doped with Nitrogen

Abstract—The development of modern equipment is limited by the physical and mechanical characteristics of the produced alloys, properties of which are often determined and enhanced by introduced alloying components. One of the alloying elements that have been very actively introduced in recent years is nitrogen. As a rule, alloying with nitrogen is carried out by ferroalloys, less often by gaseous nitrogen, which has significant advantages. In the processes of special electrometallurgy, alloying with nitrogen can be performed using, for example, nitrogen-containing plasma. Such a method may be feasible in the production of powder metal by spraying the ingot with nitrogen-containing plasma. It is known that performance properties of the products made of powder metal are significantly higher than those of cast metal. This stimulated the investigation of the properties of a product obtained from nitrided EP741NP powder alloy. In this work, a study of changes in the chemical composition, microstructure and microhardness of EP741NP alloy samples was carried out. The studied material was nitrided metal powders made on a plasma centrifugal atomization unit (PCAU) and ingots from granules obtained by hot isostatic pressing (HIP). The chemical composition of the obtained samples was determined by wave dispersion X-ray fluorescence spectrometry. In order to study the microstructure of metal powders and ingots, the methods of scanning electron microscopy with EDXS were used. Microhardness of the samples was assessed using a microhardness tester by the Vickers method. The analysis of gas impurities was carried out on a gas analyzer. It is shown that nitriding of heat-resistant EP741NP nickel alloy is possible at the stage of metal powder production, without significant loss of alloying components and a sharp change in chemical composition. An increase in microhardness of the obtained nitrided samples was noted in comparison with the initial one.

Активационные характеристики вязкоупругих свойств жаропрочного сплава на основе системы Ni-Co-Cr, упрочненного объемным азотированием

The results of measurements of the high-temperature internal friction background of the heat-resistant alloy VZh171 in the initial state and after volume nitriding presented. The obtained data used to study the regularities of the transition from the elastic to the viscoelastic state of the material at elevated temperatures. Nitriding the alloy leads to an increase in the transition temperature to the viscoelastic state from 571 K (initial state) to 763 K (after nitriding). The values of activation energy of the high-temperature internal friction background obtained: U f = 0.63 ± 0.01 eV for the alloy VZh171 in the initial state and U f = 0.59 ± 0.01 eV for the alloy after volume nitriding. The activation energies U 0 of the processes responsible for the formation of the viscoelastic properties of the substance are estimated: U 0 ≈ 2.52 eV for the alloy in the initial state, U 0 ≈ 2.36 eV for the nitrided alloy. The obtained values U 0 correspond to the self-diffusion activation energy in nickel, the main component of the alloy matrix. The appearance of dispersed nitride phases in the matrix leads to a decrease in the activation energy of viscoelasticity processes by about 6%. Possible reasons for the change in the transition temperature and the activation energy of the viscoelastic state at moderately high temperatures as a result of nitriding discussed.

Effect of N2/Ar Pressure Ratio On Microstructure, Mechanical Properties, Corrosion Properties and High Temperature Steam Oxidation Performance of Alticrnita High Entropy Alloy Nitride Coatings for Atf

Effect of N2/Ar Pressure Ratio On Microstructure, Mechanical Properties, Corrosion Properties and High Temperature Steam Oxidation Performance of Alticrnita High Entropy Alloy Nitride Coatings for Atf

Rf Magnetron Sputtering Power Induced Changes in Structure and Properties of (Tivcrnbsitaby)N High-Entropy Alloy Nitride Coatings

Rf Magnetron Sputtering Power Induced Changes in Structure and Properties of (Tivcrnbsitaby)N High-Entropy Alloy Nitride Coatings

Improving vacuum gas nitriding of a Ti-based alloy via surface solid phase transformation

The traditional surface nitriding technology of titanium alloy usually adopts the temperature above 700 °C to ensure the nitriding effect, but the high temperature will lead to the deterioration of the Matrix structure and reduce the mechanical properties. In this paper, the metastable β phase was formed on the surface of TiZrAl alloy by laser quenching, compared with the 10 μm thick nitrided layer mainly composed of (TiZr)N and α-Ti phases under the traditional process, the thickness and nitrogen content of nitrided layer were increased by the thermodynamic driving force of β→α phase transformation and the kinetic diffusion of phase interface, the effective thickness of nitrided layer was increased to 15 μm via nitriding at 500 °C. the (TiZr)N and α-Ti phases were dominant in the surface layer, and (TiZr)N0.3 and α-Ti phases were dominant in the inner layer, nitriding layer hardness up to 1200HV. In this paper, a novel nitriding technology is used to achieve excellent nitriding effect at low temperature, which has important reference significance for surface nitriding and carburizing of titanium alloys and other alloy materials.

Efficacy of an external chromia layer in reducing nitridation of high temperature alloys

Six high temperature alloys have been exposed in N2/H2 environments at 900 °C. In order to study the efficacy of a chromia barrier layer against nitrogen ingress, experiments were performed in two environments having the same N2/H2 ratio but slightly different water content, chromia formation being spontaneous in one case only. The samples were evaluated by SEM/STEM/EDX, XRD, gravimetry and GD-OES. The presence of an external chromia scale reduced nitridation of the alloy by 50–95%. Furthermore, in the presence of a continuous alumina layer no nitridation of the alloy was detected.

Ultrawide-bandgap semiconductors: An overview

Ultrawide-bandgap (UWBG) semiconductor technology is presently going through a renaissance exemplified by advances in material-level understanding, extensions of known concepts to new materials, novel device concepts, and new applications. This focus issue presents a timely selection of papers spanning the current state of the art in UWBG materials and applications, including both experimental results and theoretical developments. It covers broad research subtopics on UWBG bulk crystals and substrate technologies, UWBG defect science and doping, UWBG epitaxy, UWBG electronic and optoelectronic properties, and UWBG power devices and emitters. In this overview article, we consolidate the fundamentals and background of key UWBG semiconductors including aluminum gallium nitride alloys (AlxGa1–xN), boron nitride (BN), diamond, β-phase gallium oxide (β-Ga2O3), and a number of other UWBG binary and ternary oxides.Graphical Abstract

Gaseous Nitriding of Binary Ni-Cr Alloys – Observation and Interpretation of Microstructural Features

Gaseous Nitriding of Binary Ni-Cr Alloys – Observation and Interpretation of Microstructural Features