Achieving strength-ductility synergy of spark plasma sintered (CoCrNi)94Al3Ti3 medium-entropy alloy via post-sintering in-situ precipitation treatment

The single-phase face-centered cubic medium-entropy alloys (MEAs) normally have coarse grains in as-cast state, which exhibit insufficient strength for engineering applications. Here, a superior tensile strength-ductility synergy in a fine grained (CoCrNi)94Al3Ti3 MEA hardened by nanoscale L12 preci...

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Main Authors: Shifeng Luo, Nan Wang, Yan Wang, Xiang Li, Xiaogang Fang, Hongwei Zhou, Jieming Chen, Xinyu Yang, Jiuxing Zhang
Format: Article
Language:English
Published: Elsevier 2024-11-01
Series:Journal of Materials Research and Technology
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Online Access:http://www.sciencedirect.com/science/article/pii/S2238785424020957
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author Shifeng Luo
Nan Wang
Yan Wang
Xiang Li
Xiaogang Fang
Hongwei Zhou
Jieming Chen
Xinyu Yang
Jiuxing Zhang
author_facet Shifeng Luo
Nan Wang
Yan Wang
Xiang Li
Xiaogang Fang
Hongwei Zhou
Jieming Chen
Xinyu Yang
Jiuxing Zhang
author_sort Shifeng Luo
collection DOAJ
description The single-phase face-centered cubic medium-entropy alloys (MEAs) normally have coarse grains in as-cast state, which exhibit insufficient strength for engineering applications. Here, a superior tensile strength-ductility synergy in a fine grained (CoCrNi)94Al3Ti3 MEA hardened by nanoscale L12 precipitates was fabricated by spark plasma sintering (SPS) and post-sintering in-situ precipitation treatment. The SPSed MEAs have a fine grain size of ⁓ 5 μm, and a high number density of L12 precipitates form after in-situ annealing within the SPS machine. A high tensile yield strength of 1141 MPa with an adequate elongation to fracture of 25.8% was achieved in (CoCrNi)94Al3Ti3 MEA after annealing at 700 °C for 4 h. Electron backscattered diffraction and transmission electron microscopy characterizations indicate that the superior mechanical properties mainly originate from fine grains and the coherent spherical L12 precipitates. The dislocation slips and stacking faults prevail in all SPSed MEAs during tensile deformation, while extra Lomer-Cottrell locks are observed in annealed MEAs. The deformation twinning is absent in these precipitation-hardened MEAs with a low stacking fault energy, which may be attributed to the fine grains and numerous nanoscale L12 precipitates. This study not only confirms the effectiveness of powder metallurgy when sintering and precipitation are combined in-situ during the SPS cycle, but also provide guidance for the microstructure regulation process and practical applications of SPSed HEAs/MEAs.
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spelling doaj-art-e0015b1a27084826ada62cefa6d9740c2025-08-20T02:35:26ZengElsevierJournal of Materials Research and Technology2238-78542024-11-013350351410.1016/j.jmrt.2024.09.090Achieving strength-ductility synergy of spark plasma sintered (CoCrNi)94Al3Ti3 medium-entropy alloy via post-sintering in-situ precipitation treatmentShifeng Luo0Nan Wang1Yan Wang2Xiang Li3Xiaogang Fang4Hongwei Zhou5Jieming Chen6Xinyu Yang7Jiuxing Zhang8Key Laboratory of Green Fabrication and Surface Technology of Advanced Metal Materials (Anhui University of Technology), Ministry of Education, Maanshan, 243002, PR China; School of Materials Science and Engineering, Hefei University of Technology, Hefei, 230009, PR China; Corresponding author. Key Laboratory of Green Fabrication and Surface Technology of Advanced Metal Materials (Anhui University of Technology), Ministry of Education, Maanshan, 243002, PR China.School of Materials Science and Engineering, Hefei University of Technology, Hefei, 230009, PR ChinaSchool of Materials Science and Engineering, Hefei University of Technology, Hefei, 230009, PR ChinaSchool of Materials Science and Engineering, Hefei University of Technology, Hefei, 230009, PR ChinaSchool of Materials Science and Engineering, Hefei University of Technology, Hefei, 230009, PR ChinaKey Laboratory of Green Fabrication and Surface Technology of Advanced Metal Materials (Anhui University of Technology), Ministry of Education, Maanshan, 243002, PR ChinaLuoyang Ship Materials Research Institution, Luoyang, 471023, PR ChinaSchool of Materials Science and Engineering, Hefei University of Technology, Hefei, 230009, PR ChinaSchool of Materials Science and Engineering, Hefei University of Technology, Hefei, 230009, PR ChinaThe single-phase face-centered cubic medium-entropy alloys (MEAs) normally have coarse grains in as-cast state, which exhibit insufficient strength for engineering applications. Here, a superior tensile strength-ductility synergy in a fine grained (CoCrNi)94Al3Ti3 MEA hardened by nanoscale L12 precipitates was fabricated by spark plasma sintering (SPS) and post-sintering in-situ precipitation treatment. The SPSed MEAs have a fine grain size of ⁓ 5 μm, and a high number density of L12 precipitates form after in-situ annealing within the SPS machine. A high tensile yield strength of 1141 MPa with an adequate elongation to fracture of 25.8% was achieved in (CoCrNi)94Al3Ti3 MEA after annealing at 700 °C for 4 h. Electron backscattered diffraction and transmission electron microscopy characterizations indicate that the superior mechanical properties mainly originate from fine grains and the coherent spherical L12 precipitates. The dislocation slips and stacking faults prevail in all SPSed MEAs during tensile deformation, while extra Lomer-Cottrell locks are observed in annealed MEAs. The deformation twinning is absent in these precipitation-hardened MEAs with a low stacking fault energy, which may be attributed to the fine grains and numerous nanoscale L12 precipitates. This study not only confirms the effectiveness of powder metallurgy when sintering and precipitation are combined in-situ during the SPS cycle, but also provide guidance for the microstructure regulation process and practical applications of SPSed HEAs/MEAs.http://www.sciencedirect.com/science/article/pii/S2238785424020957Spark plasma sinteringMedium-entropy alloysIn-situ precipitation treatmentMicrostructureMechanical properties
spellingShingle Shifeng Luo
Nan Wang
Yan Wang
Xiang Li
Xiaogang Fang
Hongwei Zhou
Jieming Chen
Xinyu Yang
Jiuxing Zhang
Achieving strength-ductility synergy of spark plasma sintered (CoCrNi)94Al3Ti3 medium-entropy alloy via post-sintering in-situ precipitation treatment
Journal of Materials Research and Technology
Spark plasma sintering
Medium-entropy alloys
In-situ precipitation treatment
Microstructure
Mechanical properties
title Achieving strength-ductility synergy of spark plasma sintered (CoCrNi)94Al3Ti3 medium-entropy alloy via post-sintering in-situ precipitation treatment
title_full Achieving strength-ductility synergy of spark plasma sintered (CoCrNi)94Al3Ti3 medium-entropy alloy via post-sintering in-situ precipitation treatment
title_fullStr Achieving strength-ductility synergy of spark plasma sintered (CoCrNi)94Al3Ti3 medium-entropy alloy via post-sintering in-situ precipitation treatment
title_full_unstemmed Achieving strength-ductility synergy of spark plasma sintered (CoCrNi)94Al3Ti3 medium-entropy alloy via post-sintering in-situ precipitation treatment
title_short Achieving strength-ductility synergy of spark plasma sintered (CoCrNi)94Al3Ti3 medium-entropy alloy via post-sintering in-situ precipitation treatment
title_sort achieving strength ductility synergy of spark plasma sintered cocrni 94al3ti3 medium entropy alloy via post sintering in situ precipitation treatment
topic Spark plasma sintering
Medium-entropy alloys
In-situ precipitation treatment
Microstructure
Mechanical properties
url http://www.sciencedirect.com/science/article/pii/S2238785424020957
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