T2 phase site occupancies in the Cr-Si-B system: a combined synchroton-XRD/first-principles study

SCRIPTA MATERIALIA

卷:199

Article

Dorini, Thiago T.¹  de Freitas, Bruno X.²  Ferreira, Pedro P.²  Chaia, Nabil²  Suzuki, Paulo A.²  Joubert, Jean-Marc³  Nunes, Carlos A.²  Coelho, Gilberto C.²  Eleno, Luiz T. F.² 

[1] Univ Lorraine, IJL, CNRS, Nancy, France

[2] Univ Sao Paulo EEL USP, Mat Engn Dept Demar, Computat Mat Sci Grp ComputEEL MatSci, Escola Engn Lorena, Lorena, SP, Brazil

[3] Univ Paris Est Creteil, ICMPE, CNRS, UMR 7182, 2 Rue Henri Dunant, F-94320 Thiais, France

关键词: X-ray diffraction (XRD);    Density Functional Theory (DFT);    Refractory metals;    Cr-Si-B;    Intermetallics;   

DOI  :  10.1016/j.scriptamat.2021.113854

来源: Elsevier

【 摘 要 】

Boron and Silicon site occupancies of the T2 phase in the Cr-Si-B system were investigated experimentally and by first-principles electronic-structure calculations. A sample with nominal composition Cr0.625B0.175Si0.2 was arc-melted under argon, encapsulated in a quartz-tube and heat-treated at 1400 degrees C for 96 hours. It was then analyzed using Scanning Electron Microscopy (SEM) and X-Ray Diffractometry (XRD) with synchrotron radiation. An excellent agreement was obtained between experiments and theoretical calculations, revealing that Si occupies preferably the 4 a sublattice of the structure, as boron atoms in 8 h nearest-neighbors form very stable dumbbell bonds. Site preferences are thus a key factor for the stabilization of the structure. The results of this work provide important information to support a better description of this phase in alloys with Si and B, since T2 phases are known to occur in many important Transition Metal-Si-B ternary systems, such as Nb/Mo/W/Ta/V-Si-B. (c) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

【 授权许可】

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