Tensile ductility of an AlCoCrFeNi multi-phase high-entropy alloy through hot isostatic pressing (HIP) and homogenization

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

卷:647

Article

Tang, Zhi^1,2  Senkov, Oleg N.³  Parish, Chad M.⁴  Zhang, Chuan⁵  Zhang, Fan⁵  Santodonato, Louis J.^1,4  Wang, Gongyao¹  Zhao, Guangfeng⁶  Yang, Fuqian⁶  Liaw, Peter K.¹ 

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

[2] Virginia Tech, Dept Mat Sci & Engn, Blacksburg, VA 24061 USA

[3] Air Force Res Lab, Mat & Mfg Directorate, Wright Patterson AFB, OH 45433 USA

[4] Oak Ridge Natl Lab, Oak Ridge, TN 37831 USA

[5] CompuTherrn LLC, Madison, WI 53719 USA

[6] Univ Kentucky, Dept Chem & Mat Engn, Lexington, KY 40506 USA

关键词: High-entropy alloys;    Microstructures;    Tensile properties;    Heat treatment;    Thermodynamic modeling;    Crack initiation;   

DOI  :  10.1016/j.msea.2015.08.078

来源: Elsevier

【 摘 要 】

The microstructure and phase composition of an AlCoCrFeNi high-entropy alloy (HEA) were studied in as-cast (AlCoCrFeNi-AC, AC represents as-cast) and homogenized (AlCoCrFeNi-HP, HP signifies hot iso-static pressed and homogenized) conditions. The AlCoCrFeNi-AC ally has a dendritric structure in the consisting primarily of a nano-lamellar mixture of A2 (disordered body-centered-cubic (BCC)) and B2 (ordered BCC) phases, formed by an eutectic reaction. The homogenization heat treatment, consisting of hot isostatic pressed for 1 h at 1100 degrees C, 207 MPa and annealing at 1150 degrees C for 50 h, resulted in an increase in the volume fraction of the A1 phase and formation of a Sigma (sigma) phase. Tensile properties in as-cast and homogenized conditions are reported at 700 degrees C. The ultimate tensile strength was virtually unaffected by heat treatment, and was 396 +/- 4 MPa at 700 degrees C. However, homogenization produced a noticeable increase in ductility. The AlCoCrFeNi-AC alloy showed a tensile elongation of only 1.0%, while after the heat-treatment, the elongation of AlCoCrFeNi-HP was 11.7%. Thermodynamic modeling of nonequilibrium and equilibrium phase diagrams for the AlCoCrFeNi HEA gave good agreement with the experimental observations of the phase contents in the AlCoCrFeNi-AC and AlCoCrFeNi-HP. The reasons for the improvement of ductility after the heat treatment and the crack initiation subjected to tensile loading were discussed. Published by Elsevier B.V.

【 授权许可】

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