Property enhancement of CoCrNi medium-entropy alloy by introducing nano-scale features

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:817

Article

Li, Mingyang¹  Guo, Yuanhang¹  Li, Wuming¹  Zhang, Yanwen^2,3  Chang, Yongqin¹ 

[1] Univ Sci & Technol Beijing, Sch Mat Sci & Engn, Beijing 100083, Peoples R China

[2] Oak Ridge Natl Lab, Mat Sci & Technol Div, Oak Ridge, TN 37831 USA

[3] Univ Tennessee, Dept Mat Sci & Engn, Knoxville, TN 37996 USA

关键词: Medium-entropy alloy;    ODS;    Carbide;    Orientation relationship;    Dislocation locks;   

DOI  :  10.1016/j.msea.2021.141368

来源: Elsevier

【 摘 要 】

CoCrNi -medium-entropy alloy (MEA) has been widely investigated due to its superior mechanical properties that overcome strength-ductility tradeoff. Here we show further property enhancement of CoCrNi MEA by introducing nano-scale features. Both CoCrNi and oxide dispersion strengthened (ODS) CoCrNi are fabricated by mechanical alloying and spark plasma sintering. Microstructural characterization and mechanical testing of these nanostructured MEAs revealed that the nano-scale features significantly improves the strength of the alloys. In ODS-CoCrNi MEA, Y2Ti2O7 oxides with an average diameter of 7.3 +/- 3.2 nm are incoherent with the matrix, and a specific orientation relationship exists between Y2Ti2O7 and the matrix, which is [011]Y2Ti2O7//[011]Matrix, (400)Y2Ti2O7//(200)Matrix and (222)Y2Ti2O7//(111)Matrix. The recrystallization and grain growth processes are effectively suppressed by the introduction of Y2Ti2O7 nanoparticles. Strengthening mechanism analyses indicate that the strength improvement of ODS-CoCrNi is mainly ascribed to the precipitation strengthening of Y2Ti2O7

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