The Experts below are selected from a list of 51 Experts worldwide ranked by ideXlab platform
Adrian Leyland - One of the best experts on this subject based on the ideXlab platform.
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On the Nitrogen-Induced Lattice Expansion of a Non-stainless Austenitic Steel, Invar 36^®, Under Triode Plasma Nitriding
Metallurgical and Materials Transactions A, 2020Co-Authors: Allan Matthews, Adrian LeylandAbstract:Chromium, as a strong Nitride-Forming Element, is widely regarded to be an “essential” ingredient for the formation of a nitrogen-expanded lattice in thermochemical nitrogen diffusion treatments of austenitic (stainless) steels. In this article, a proprietary “chrome-free” austenitic iron-nickel alloy, Invar^® 36 (Fe-36Ni, in wt pct), is characterized after triode plasma nitriding (TPN) treatments at 400 °C to 450 °C and compared with a “stainless” austenitic counterpart RA 330^® (Fe-19Cr-35Ni, in wt pct) treated under equivalent nitriding conditions. Cr does indeed appear to play a pivotal role in colossal nitrogen supersaturation (and hence anisotropic lattice expansion and superior surface hardening) of austenitic steel under low-temperature (≤ 450 °C) nitrogen diffusion. Nevertheless, this work reveals that nitrogen-induced lattice expansion occurs below the Nitride-containing surface layer in Invar 36 alloy after TPN treatment, implying that Cr is not a necessity for the nitrogen-interstitial induced lattice expansion phenomenon to occur, also suggesting another type of γ _N.
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On the Nitrogen-Induced Lattice Expansion of a Non-stainless Austenitic Steel, Invar 36 ® , Under Triode Plasma Nitriding
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2019Co-Authors: Allan Matthews, Adrian LeylandAbstract:Chromium, as a strong Nitride-Forming Element, is widely regarded to be an “essential” ingredient for the formation of a nitrogen-expanded lattice in thermochemical nitrogen diffusion treatments of austenitic (stainless) steels. In this article, a proprietary “chrome-free” austenitic iron-nickel alloy, Invar® 36 (Fe-36Ni, in wt pct), is characterized after triode plasma nitriding (TPN) treatments at 400 °C to 450 °C and compared with a “stainless” austenitic counterpart RA 330® (Fe-19Cr-35Ni, in wt pct) treated under equivalent nitriding conditions. Cr does indeed appear to play a pivotal role in colossal nitrogen supersaturation (and hence anisotropic lattice expansion and superior surface hardening) of austenitic steel under low-temperature (≤ 450 °C) nitrogen diffusion. Nevertheless, this work reveals that nitrogen-induced lattice expansion occurs below the Nitride-containing surface layer in Invar 36 alloy after TPN treatment, implying that Cr is not a necessity for the nitrogen-interstitial induced lattice expansion phenomenon to occur, also suggesting another type of γN.
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Structure and mechanical properties of nitrogen-containing Zr?Cu based thin films deposited by pulsed magnetron sputtering
Journal of Physics D, 2008Co-Authors: O Jimenez, Allan Matthews, M. Audronis, Mark A. Baker, Adrian LeylandAbstract:Pulsed-dc magnetron sputtered zirconium?copper films were deposited with a range of different compositions (of varying Zr/Cu ratio and nitrogen content). Adding nitrogen to the low-miscibility binary Zr?Cu system as a solution hardening and/or Nitride-Forming Element permits the deposition of two- (or multi-) phase nanostructured coatings. Structure and morphology of the coatings was studied by means of x-ray diffraction and scanning electron microscopy. Elemental compositions and Zr/Cu atomic ratios were obtained by quantitative energy-dispersive x-ray analysis. Nanoindentation measurements were made to evaluate coating hardness and elastic modulus. Coating structure was found to depend on the chemical composition; at low nitrogen contents coatings exhibited a columnar morphology, while the maximum N2 flow rate used resulted in a compact and fully dense coating structure. ZrCu(N) films produced with little or no nitrogen (N2 gas flow rates of 0 and 1?sccm) showed a partially amorphous structure with broad, low intensity Zr and Cu x-ray diffraction peaks. An increase in N2 flow rate (3?sccm) developed coatings with nanocrystalline Zr and ZrN phases for the Zr-rich coatings, while increased amorphization, followed by Cu segregation, was observed for Cu-rich coatings deposited at the same N2 flow rate. At the highest N2 flow rate of 5?sccm crystalline ZrN-based coatings were produced. Zr-rich coatings deposited at 0, 1 and 3?sccm N2 flow rates (with Zr/Cu ratios of ~2.2?6.2) demonstrated slightly higher hardness values than coatings exhibiting lower Zr/Cu ratios, while the elastic modulus in the majority of cases showed an opposite trend. This behaviour is shown to correlate well with film chemical composition and the expected mechanical properties of the resulting constituent phases?the exception being the nitrogen-free coatings which (surprisingly) appeared to develop a lower elastic modulus with increasing copper content.
Allan Matthews - One of the best experts on this subject based on the ideXlab platform.
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On the Nitrogen-Induced Lattice Expansion of a Non-stainless Austenitic Steel, Invar 36^®, Under Triode Plasma Nitriding
Metallurgical and Materials Transactions A, 2020Co-Authors: Allan Matthews, Adrian LeylandAbstract:Chromium, as a strong Nitride-Forming Element, is widely regarded to be an “essential” ingredient for the formation of a nitrogen-expanded lattice in thermochemical nitrogen diffusion treatments of austenitic (stainless) steels. In this article, a proprietary “chrome-free” austenitic iron-nickel alloy, Invar^® 36 (Fe-36Ni, in wt pct), is characterized after triode plasma nitriding (TPN) treatments at 400 °C to 450 °C and compared with a “stainless” austenitic counterpart RA 330^® (Fe-19Cr-35Ni, in wt pct) treated under equivalent nitriding conditions. Cr does indeed appear to play a pivotal role in colossal nitrogen supersaturation (and hence anisotropic lattice expansion and superior surface hardening) of austenitic steel under low-temperature (≤ 450 °C) nitrogen diffusion. Nevertheless, this work reveals that nitrogen-induced lattice expansion occurs below the Nitride-containing surface layer in Invar 36 alloy after TPN treatment, implying that Cr is not a necessity for the nitrogen-interstitial induced lattice expansion phenomenon to occur, also suggesting another type of γ _N.
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On the Nitrogen-Induced Lattice Expansion of a Non-stainless Austenitic Steel, Invar 36 ® , Under Triode Plasma Nitriding
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2019Co-Authors: Allan Matthews, Adrian LeylandAbstract:Chromium, as a strong Nitride-Forming Element, is widely regarded to be an “essential” ingredient for the formation of a nitrogen-expanded lattice in thermochemical nitrogen diffusion treatments of austenitic (stainless) steels. In this article, a proprietary “chrome-free” austenitic iron-nickel alloy, Invar® 36 (Fe-36Ni, in wt pct), is characterized after triode plasma nitriding (TPN) treatments at 400 °C to 450 °C and compared with a “stainless” austenitic counterpart RA 330® (Fe-19Cr-35Ni, in wt pct) treated under equivalent nitriding conditions. Cr does indeed appear to play a pivotal role in colossal nitrogen supersaturation (and hence anisotropic lattice expansion and superior surface hardening) of austenitic steel under low-temperature (≤ 450 °C) nitrogen diffusion. Nevertheless, this work reveals that nitrogen-induced lattice expansion occurs below the Nitride-containing surface layer in Invar 36 alloy after TPN treatment, implying that Cr is not a necessity for the nitrogen-interstitial induced lattice expansion phenomenon to occur, also suggesting another type of γN.
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Structure and mechanical properties of nitrogen-containing Zr?Cu based thin films deposited by pulsed magnetron sputtering
Journal of Physics D, 2008Co-Authors: O Jimenez, Allan Matthews, M. Audronis, Mark A. Baker, Adrian LeylandAbstract:Pulsed-dc magnetron sputtered zirconium?copper films were deposited with a range of different compositions (of varying Zr/Cu ratio and nitrogen content). Adding nitrogen to the low-miscibility binary Zr?Cu system as a solution hardening and/or Nitride-Forming Element permits the deposition of two- (or multi-) phase nanostructured coatings. Structure and morphology of the coatings was studied by means of x-ray diffraction and scanning electron microscopy. Elemental compositions and Zr/Cu atomic ratios were obtained by quantitative energy-dispersive x-ray analysis. Nanoindentation measurements were made to evaluate coating hardness and elastic modulus. Coating structure was found to depend on the chemical composition; at low nitrogen contents coatings exhibited a columnar morphology, while the maximum N2 flow rate used resulted in a compact and fully dense coating structure. ZrCu(N) films produced with little or no nitrogen (N2 gas flow rates of 0 and 1?sccm) showed a partially amorphous structure with broad, low intensity Zr and Cu x-ray diffraction peaks. An increase in N2 flow rate (3?sccm) developed coatings with nanocrystalline Zr and ZrN phases for the Zr-rich coatings, while increased amorphization, followed by Cu segregation, was observed for Cu-rich coatings deposited at the same N2 flow rate. At the highest N2 flow rate of 5?sccm crystalline ZrN-based coatings were produced. Zr-rich coatings deposited at 0, 1 and 3?sccm N2 flow rates (with Zr/Cu ratios of ~2.2?6.2) demonstrated slightly higher hardness values than coatings exhibiting lower Zr/Cu ratios, while the elastic modulus in the majority of cases showed an opposite trend. This behaviour is shown to correlate well with film chemical composition and the expected mechanical properties of the resulting constituent phases?the exception being the nitrogen-free coatings which (surprisingly) appeared to develop a lower elastic modulus with increasing copper content.
Tom Bell - One of the best experts on this subject based on the ideXlab platform.
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Current Status of Supersaturated Surface Engineered S-Phase Materials
Key Engineering Materials, 2020Co-Authors: Tom BellAbstract:The present paper reviews the scientific development of our understanding of S-Phase. It is now known that S-Phase formation is an example of para equilibrium phenomena. A necessary but not sufficient condition for S-Phase formation is the presence of an fcc structure at least in part with structure in the starting alloy. An essential requirement is for a Nitride Forming Element to be present particularly Cr. After surface engineering with carbon, nitrogen or carbon and nitrogen to generate supersaturated solid solutions, the various tribological, corrosion, mechanical and microstructural studies are reviewed for the various alloy systems. The current industrial status of S-Phase technology on an international basis is examined and the potential for its acceptance in china is discussed.
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Current status of supersaturated surface engineered S phase materials
International Heat Treatment & Surface Engineering, 2020Co-Authors: Tom BellAbstract:AbstractThe present paper reviews the scientific development of the understanding of S phase. It is now known that S phase formation is an example of paraequilibrium phenomena. A necessary but not sufficient condition for S phase formation is the presence of a face centred cubic (fcc) structure at least in part with structure in the starting alloy. An essential requirement is for a Nitride Forming Element to be present, particularly Cr. After surface engineering with carbon, nitrogen or carbon and nitrogen to generate supersaturated solid solutions, the various tribological, corrosion, mechanical and microstructural studies are reviewed for the various alloy systems. The current industrial status of S phase technology on an international basis is examined and the potential for its acceptance in China is discussed.
O. V. Chudina - One of the best experts on this subject based on the ideXlab platform.
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Comparison of dispersion hardening by coherent and incoherent Nitrides in nitriding of alloys based on iron, nickel, and cobalt
Metal Science and Heat Treatment, 2000Co-Authors: L. G. Petrova, O. V. ChudinaAbstract:1. A comparison of the efficiency of dispersion hardening of Ni-, Co-, and Fe-matrices has shown that steels are reinforced more strongly by coherent particles (the Mott-Nabarro model), which requires the lowes volume fraction of Nitrides and the lowest concentration of the Nitride-Forming Element in the alloy. In actual Ni- and Co-base alloys the highest hardening effect can be obtained due to incoherent particles too (the Orowan model) given that the Nitride particles have optimum geometrical characteristics (the size and the distance between the particles). 2. The results of measurements of the microhardness of Nitrided alloys agree well with the calculated data, which makes it possible to use models, in particular, for comparing the level of the hardening of individual alloys by various Nitrides or segregations of different sizes. 3. The results of the evaluation of dispersion hardening by Nitrides can be used for choosing nitriding regimes with the aim of providing maximum hardening
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Prediction of hardening of binary iron alloys due to nitriding on the basis of calculation models
Metal Science and Heat Treatment, 2000Co-Authors: L. G. Petrova, O. V. ChudinaAbstract:1. The studied method for modelling the hardening of Nitrided layers as a function of their structure makes it possible to predict successfully the hardness of steels after surface impregnation. 2. The performed calculations and experiments have shown that the alloying Elements (Cr, V, Mo, W, Ti) increase substantially the efficiency of the solid-solution hardening by nitrogen due to the enhanced dissolution of nitrogen in iron. 3. The calculations of dispersion hardening of binary Fe-AE alloys by Nitrides have shown that the hardness can be increased to a maximum level due to the formation of coherent Nitride particles of the alloying Elements, Ti, Cr, and V in the first place. This is confirmed by experimental results. 4. The described method can be used for optimizing the chemical composition of steels subjected to nitriding from the standpoint of the amount and type of the Nitride-Forming Element with the aim to provide the requisite hardness level. 5. By controlling the nitriding parameters and using subsequent aging at a specified temperature we can obtain various structures in the zone of internal nitriding and optimize the mechanical properties (hardness in particular) of steels after surface impregnation.
L. G. Petrova - One of the best experts on this subject based on the ideXlab platform.
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Comparison of dispersion hardening by coherent and incoherent Nitrides in nitriding of alloys based on iron, nickel, and cobalt
Metal Science and Heat Treatment, 2000Co-Authors: L. G. Petrova, O. V. ChudinaAbstract:1. A comparison of the efficiency of dispersion hardening of Ni-, Co-, and Fe-matrices has shown that steels are reinforced more strongly by coherent particles (the Mott-Nabarro model), which requires the lowes volume fraction of Nitrides and the lowest concentration of the Nitride-Forming Element in the alloy. In actual Ni- and Co-base alloys the highest hardening effect can be obtained due to incoherent particles too (the Orowan model) given that the Nitride particles have optimum geometrical characteristics (the size and the distance between the particles). 2. The results of measurements of the microhardness of Nitrided alloys agree well with the calculated data, which makes it possible to use models, in particular, for comparing the level of the hardening of individual alloys by various Nitrides or segregations of different sizes. 3. The results of the evaluation of dispersion hardening by Nitrides can be used for choosing nitriding regimes with the aim of providing maximum hardening
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Prediction of hardening of binary iron alloys due to nitriding on the basis of calculation models
Metal Science and Heat Treatment, 2000Co-Authors: L. G. Petrova, O. V. ChudinaAbstract:1. The studied method for modelling the hardening of Nitrided layers as a function of their structure makes it possible to predict successfully the hardness of steels after surface impregnation. 2. The performed calculations and experiments have shown that the alloying Elements (Cr, V, Mo, W, Ti) increase substantially the efficiency of the solid-solution hardening by nitrogen due to the enhanced dissolution of nitrogen in iron. 3. The calculations of dispersion hardening of binary Fe-AE alloys by Nitrides have shown that the hardness can be increased to a maximum level due to the formation of coherent Nitride particles of the alloying Elements, Ti, Cr, and V in the first place. This is confirmed by experimental results. 4. The described method can be used for optimizing the chemical composition of steels subjected to nitriding from the standpoint of the amount and type of the Nitride-Forming Element with the aim to provide the requisite hardness level. 5. By controlling the nitriding parameters and using subsequent aging at a specified temperature we can obtain various structures in the zone of internal nitriding and optimize the mechanical properties (hardness in particular) of steels after surface impregnation.