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Atomic-scale observation and analysis of chemical ordering in M3B2 and M5B3 borides
Hu, XB; Niu, HY; Ma, XL; Oganov, AR; Fisher, CAJ; Sheng, NC; Liu, JD; Jin, T; Sun, XF; Liu, JF; Ikuhara, Y; Ma, XL (reprint author), Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, Shenyang 110016, Liaoning, Peoples R China.; Ikuhara, Y (reprint author), Japan Fine Ceram Ctr, Nanostruct Res Lab, Nagoya, Aichi 4568587, Japan.; Oganov, AR (reprint author), SUNY Stony Brook, Inst Adv Computat Sci, Ctr Mat By Design, Dept Geosci, Stony Brook, NY 11794 USA.
2018-05-01
Source PublicationACTA MATERIALIA
ISSN1359-6454
Volume149Pages:274-284
AbstractSecondary phases precipitated in diffusion affected zones (DAZs) of a transient liquid phase (Tip) bonded Ni-based superalloy have a large impact on materials properties. Here we report an atomic-scale analysis of the crystal structures and elemental distributions within DAZ precipitates in a TLP-bonded single-crystal superalloy using a range of electron microscopy techniques. The predominant precipitate phases are found to be M3B2- and M5B3-type borides, where M is a mixture of transition metal elements. Atomically-resolved energy-dispersive X-ray spectroscopy in an aberration-corrected scanning transmission electron microscope (STEM) enabled the distributions of metal atoms within the precipitates to be determined. The observation that different metals occupy preferred sites within the crystals indicates that these phases are not uniform solid solutions, but instead are chemically ordered. Both borides contain two distinct metal lattice sites such that the phases can be described as L2SB2 and L4SB3, where L and S are elements with larger (e.g., W, Mo) and smaller (e.g., Cr, Co, Ni) atomic numbers, respectively. Ordering of W and Cr is found to be particularly strong. A systematic search for stable phases within the chemical space of the W-Cr-B ternary system using the crystal structure prediction (CSP) program USPEX provided further insights into the nature of the observed chemical ordering. This combination of STEM and CSP techniques provides a direct and robust way of determining chemical features and local structures of multicomponent phases with atomic resolution even when particle sizes are too small for analysis using conventional methods. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.; Secondary phases precipitated in diffusion affected zones (DAZs) of a transient liquid phase (Tip) bonded Ni-based superalloy have a large impact on materials properties. Here we report an atomic-scale analysis of the crystal structures and elemental distributions within DAZ precipitates in a TLP-bonded single-crystal superalloy using a range of electron microscopy techniques. The predominant precipitate phases are found to be M3B2- and M5B3-type borides, where M is a mixture of transition metal elements. Atomically-resolved energy-dispersive X-ray spectroscopy in an aberration-corrected scanning transmission electron microscope (STEM) enabled the distributions of metal atoms within the precipitates to be determined. The observation that different metals occupy preferred sites within the crystals indicates that these phases are not uniform solid solutions, but instead are chemically ordered. Both borides contain two distinct metal lattice sites such that the phases can be described as L2SB2 and L4SB3, where L and S are elements with larger (e.g., W, Mo) and smaller (e.g., Cr, Co, Ni) atomic numbers, respectively. Ordering of W and Cr is found to be particularly strong. A systematic search for stable phases within the chemical space of the W-Cr-B ternary system using the crystal structure prediction (CSP) program USPEX provided further insights into the nature of the observed chemical ordering. This combination of STEM and CSP techniques provides a direct and robust way of determining chemical features and local structures of multicomponent phases with atomic resolution even when particle sizes are too small for analysis using conventional methods. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
description.department[hu, x. b. ; ma, x. l. ; liu, j. f.] chinese acad sci, inst met res, shenyang natl lab mat sci, shenyang 110016, liaoning, peoples r china ; [hu, x. b. ; fisher, c. a. j. ; ikuhara, y.] japan fine ceram ctr, nanostruct res lab, nagoya, aichi 4568587, japan ; [niu, h. y. ; oganov, a. r.] suny stony brook, inst adv computat sci, ctr mat by design, dept geosci, stony brook, ny 11794 usa ; [ma, x. l.] lanzhou univ technol, sch mat sci & engn, lanzhou 730050, gansu, peoples r china ; [oganov, a. r.] skolkovo innovat ctr, skolkovo inst sci & technol, 5 nobel st, moscow 143026, russia ; [oganov, a. r.] northwestern polytech univ, sch mat sci & engn, int ctr mat discovery, xian 710072, shaanxi, peoples r china ; [oganov, a. r.] moscow inst phys & technol, dolgoprudnyi 141700, moscow region, russia ; [sheng, n. c. ; liu, j. d. ; jin, t. ; sun, x. f.] chinese acad sci, inst met res, superalloys div, shenyang 110016, liaoning, peoples r china ; [ikuhara, y.] univ tokyo, inst engn innovat, tokyo 1138586, japan
KeywordCrystal-structure Prediction Total-energy Calculations Nickel-base Superalloys Ni-based Superalloy X-ray Spectroscopy Wave Basis-set Probe Tomography Polycrystalline Superalloy Grain-boundary Resolution
Subject AreaMaterials Science, Multidisciplinary ; Metallurgy & Metallurgical Engineering
Funding OrganizationNational Natural Science Foundation of China [11327901]; Russian Science Foundation [16-13-10459]; MEXT, Japan [12024046]
Indexed BySCI
Language英语
Document Type期刊论文
Identifierhttp://ir.imr.ac.cn/handle/321006/79326
Collection中国科学院金属研究所
Corresponding AuthorMa, XL (reprint author), Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, Shenyang 110016, Liaoning, Peoples R China.; Ikuhara, Y (reprint author), Japan Fine Ceram Ctr, Nanostruct Res Lab, Nagoya, Aichi 4568587, Japan.; Oganov, AR (reprint author), SUNY Stony Brook, Inst Adv Computat Sci, Ctr Mat By Design, Dept Geosci, Stony Brook, NY 11794 USA.
Recommended Citation
GB/T 7714
Hu, XB,Niu, HY,Ma, XL,et al. Atomic-scale observation and analysis of chemical ordering in M3B2 and M5B3 borides[J]. ACTA MATERIALIA,2018,149:274-284.
APA Hu, XB.,Niu, HY.,Ma, XL.,Oganov, AR.,Fisher, CAJ.,...&Oganov, AR .(2018).Atomic-scale observation and analysis of chemical ordering in M3B2 and M5B3 borides.ACTA MATERIALIA,149,274-284.
MLA Hu, XB,et al."Atomic-scale observation and analysis of chemical ordering in M3B2 and M5B3 borides".ACTA MATERIALIA 149(2018):274-284.
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