Microstructure and strengthening mechanisms in an FCC structured single-phase nanocrystalline Co25Ni25Fe25Al7.5Cu17.5 high-entropy alloy

被引：392

作者：

Fu, Zhiqiang ^{[1
,2
]}

Chen, Weiping ^{[1
]}

Wen, Haiming ^{[3
,4
]}

Zhang, Dalong ^{[2
]}

Chen, Zhen ^{[1
]}

Zheng, Baolong ^{[2
]}

Zhou, Yizhang ^{[2
]}

Lavernia, Enrique J. ^{[2
,5
]}

机构：

[1] S China Univ Technol, Sch Mech & Automot Engn, Guangzhou 510640, Guangdong, Peoples R China

[2] Univ Calif Davis, Dept Chem Engn & Mat Sci, Davis, CA 95616 USA

[3] Idaho State Univ, Dept Nucl Engn & Hlth Phys, Idaho Falls, ID 83402 USA

[4] Idaho Natl Lab, Characterizat & Adv PIE Div, Idaho Falls, ID 83415 USA

[5] Univ Calif Irvine, Dept Chem Engn & Mat Sci, Irvine, CA 92697 USA

来源：

ACTA MATERIALIA | 2016年 / 107卷

基金：

中国国家自然科学基金;

关键词：

Nanocrystalline; High-entropy alloys; Microstructure; Single-phase; Strengthening mechanism; HIGH-PRESSURE TORSION; ULTRAFINE-GRAINED CU; SOLID-SOLUTION; TENSILE PROPERTIES; DISLOCATION NUCLEATION; THERMAL-STABILITY; AL ADDITION; BEHAVIOR; GROWTH; EVOLUTION;

D O I：

10.1016/j.actamat.2016.01.050

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

We report on a study of the design, phase formation, microstructure, mechanical behavior and strengthening mechanisms of a novel single-phase Co25Ni25Fe25Al7.5Cu17.5 (at.%) high-entropy alloy (HEA). In this investigation, a bulk nanocrystalline (nc) Co25Ni25Fe25Al7.5Cu17.5 HEA with the face-centered cubic (FCC) crystal structure was fabricated by mechanical alloying (MA) followed by consolidation via spark plasma sintering (SPS). The X-ray diffraction (XRD) and transmission electron microscopy (TEM) results revealed that a single FCC solid-solution phase with an average grain diameter of 24 nm was produced following MA. Following SPS, bulk samples exhibiting a bimodal microstructure with both nanoscale grains and ultra-fine grains (UFGs) and with an average grain diameter of 95 nm were obtained, possessing a single FCC solid-solution phase identical to that in the milled powders. The single-phase feature of the Co25Ni25Fe25Al7.5Cu17.5 HEA principally resulted from remarkably high mutual solubility in most binary atom-pairs of the constituent elements, which appears to correspond to a high entropy of mixing. Approximately 5 vol.% of nanoscale twins were observed in the bulk nc samples. The bulk nc Co25Ni25Fe25Al7.5Cu17.5 HEA exhibits a compressive yield strength of 1795 MPa with a hardness of 454 Hv, which is dramatically higher than the yield strength of most previously reported FCC structured HEAs (-130-700 MPa). Compared to those of the bulk coarse-grained (CG) Co25Ni25Fe25Al7.5Cu17.5 HEA fabricated by arc-melting, the yield strength and Vickers hardness values of the bulk nc samples increased by 834.9% and 251.9%, respectively. Quantitative calculations of the respective contributions from each strengthening mechanism demonstrate that grain boundary strengthening and dislocation strengthening are principally responsible for the measured ultra-high strength of the bulk nc Co25Ni25Fe25Al7.5Cu17.5 HEA. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

引用

页码：59 / 71

页数：13

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