Role of Chromium in High-Dose, High-Rate, Elevated Temperature Nitrogen Implantation of Austenitic Stainless Steels

Williamson, D. L.; Ivanov, I.; Wei, Ronghua; Wilbur, P. J.

doi:10.1557/proc-235-473

Cited by 25 publications

(5 citation statements)

References 15 publications

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“…2. These results are consistent with a qualitative model proposed by Williamson et al (1992 and1994). The model suggests 1) that N solubility is effectively enhanced by N trapping near Cr atoms, which are relatively immobile at 400 °C and 2) that N added to a saturated region via implantation migrates more readily than it would in low-nitrogen SS.…”

Section: Resultssupporting

confidence: 89%

The Effects of Low-Energy-Nitrogen-Ion Implantation on the Tribological and Microstructural Characteristics of AISI 304 Stainless Steel

Wei

Shogrin

Wilbur

et al. 1994

Journal of Tribology

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The effects of nitrogen implantation conditions (ion energy, dose rate, and processing time) on the thickness and wear behavior of N-rich layers produced on 304 stainless-steel surfaces are examined. Surfaces implanted at elevated temperatures ( ~400°C) with 0.4 to 2 keV nitrogen ions at high dose rates (1.5 to 3.8 mA/cm 2 ) are compared to surfaces implanted at higher energies (30 to 60 keV) and lower current densities (0.1 to 0.25 mA/cm 2 ). The most wear-resistant surfaces are observed when the implanted-ion energy is near 1 keV and the dose is very large (>2xl0 19 ions/cm ). Typically, surfaces implanted under these optimum conditions exhibit load-bearing capabilities at least 1000 times that of the untreated material. Some comparisons are also made to surfaces processed using conventional plasma-nitriding. Samples treated using either process have wear-resistant surface layers in which the nitrogen is in solid solution in the fee phase. It is argued that the deep N migration ( >l\x,m) that occurs under low-energy implantation conditions is due to thermal diffusion that is enhanced by a mechanism other than radiationinduced vacancy production.

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Section: Resultssupporting

confidence: 89%

The Effects of Low-Energy-Nitrogen-Ion Implantation on the Tribological and Microstructural Characteristics of AISI 304 Stainless Steel

Wei

Shogrin

Wilbur

et al. 1994

Journal of Tribology

Self Cite

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“…The applicability of expanded austenite relies on the combination of excellent wear resistance and excellent localized (pitting or crevice) corrosion performance. Dissolution of nitrogen into austenitic stainless steel is usually achieved by plasma nitriding [1][2][3][4], nitrogen ion beam implantation [5][6][7][8], plasma immersion ion implantation [9][10][11] or gaseous nitriding in an ammonia-based atmosphere [12], in the temperature range 650-720 K. At the atomic scale the structure of the nitrogen-modified surface zone is mainly reported as: i) a disordered nitrogen-supersaturated solid solution, wherein the N atoms are "trapped" by Cr atoms in octahedral interstices, thus forming a short-range ordered distribution [13][14][15][16][17]; ii) a zone containing both Cr-N short-range order and Fe 4 N-like long-range order of nitrogen atoms [18,19]; iii) a mixture of the stoichiometric nitrides γ ' -Me 4 N and/or ε-Me 2-3 N phases, in a disordered high nitrogen solid solution, and even the nano-scale CrN precipitates dispersed in an expanded Fe 4 N-like long-range ordered phase [2,20,21].…”

Section: Introductionmentioning

confidence: 99%

Co-existence of γ'N phase and γN phase on nitrided austenitic Fe–Cr–Ni alloys- I. experiment

et al. 2019

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“…Trapping of N in Cr sites (trapping-detrapping model). Williamson et al [95] hypothesized that the formation of a N supersaturated phase occurs due to Cr atoms, which tend to trap N atoms in the nearby octahedral sites, with the binding energy of trap sites higher than that of regular solution sites. When all Cr trap sites are occupied, additional N can rapidly diffuse through the S phase layer to reach the leading edge of the N profile.…”

mentioning

confidence: 99%

From Austenitic Stainless Steel to Expanded Austenite-S Phase: Formation, Characteristics and Properties of an Elusive Metastable Phase

Borgioli

2020

Metals

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Austenitic stainless steels are employed in many industrial fields, due to their excellent corrosion resistance, easy formability and weldability. However, their low hardness, poor tribological properties and the possibility of localized corrosion in specific environments may limit their use. Conventional thermochemical surface treatments, such as nitriding or carburizing, are able to enhance surface hardness, but at the expense of corrosion resistance, owing to the formation of chromium-containing precipitates. An effective alternative is the so called low temperature treatments, which are performed with nitrogen- and/or carbon-containing media at temperatures, at which chromium mobility is low and the formation of precipitates is hindered. As a consequence, interstitial atoms are retained in solid solution in austenite, and a metastable supersaturated phase forms, named expanded austenite or S phase. Since the first studies, dating 1980s, the S phase has demonstrated to have high hardness and good corrosion resistance, but also other interesting properties and an elusive structure. In this review the main studies on the formation and characteristics of S phase are summarized and the results of the more recent research are also discussed. Together with mechanical, fatigue, tribological and corrosion resistance properties of this phase, electric and magnetic properties, wettability and biocompatibility are overviewed.

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Role of Chromium in High-Dose, High-Rate, Elevated Temperature Nitrogen Implantation of Austenitic Stainless Steels

Cited by 25 publications

References 15 publications

The Effects of Low-Energy-Nitrogen-Ion Implantation on the Tribological and Microstructural Characteristics of AISI 304 Stainless Steel

The Effects of Low-Energy-Nitrogen-Ion Implantation on the Tribological and Microstructural Characteristics of AISI 304 Stainless Steel

Co-existence of γ'N phase and γN phase on nitrided austenitic Fe–Cr–Ni alloys- I. experiment

From Austenitic Stainless Steel to Expanded Austenite-S Phase: Formation, Characteristics and Properties of an Elusive Metastable Phase

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