Investigation of the effects of conventional sintering and spark plasma sintering methods on the microstructural properties and hardness of nanostructured CoCrFeNi high entropy alloy

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dc.authorid0000-0001-9441-5175
dc.authorid0000-0002-8589-508X
dc.authorid0000-0002-4615-4238
dc.contributor.authorBaloglu, Ali Riza
dc.contributor.authorTekin, Mustafa
dc.contributor.authorKotan, Hasan
dc.date.accessioned2026-02-08T15:14:43Z
dc.date.available2026-02-08T15:14:43Z
dc.date.issued2024
dc.departmentBursa Teknik Üniversitesi
dc.description.abstractGraphical/Tabular CoCrFeNi HEAs were synthesized by mechanical alloying and consolidated via conventional sintering and spark plasma sintering, and microstructural properties and hardness were investigated as a function of sintering type and temperature. The result are shown in Figure A. The findings showed that the as -milled single-phase face centered cubic (fcc) crystal structure retained after conventional sintering at 1000 and 1100 degrees C whereas spark plasma sintering yielded additional Cr-rich carbide (Cr 7 C 3 ) phases at the same temperatures. Figure A. XRD and hardness results of the HEAs correlated with the microstructures Purpose: To investigate the effect of sintering type and temperature on the microstructural properties and hardness by using X-ray diffraction (XRD), focused ion beam microscopy (FIB), transmission electron microscopy (TEM), and microhardness test. Theory and Methods: High energy mechanical alloying was used to synthesize the equiatomic CoCrFeNi HEAs in nanocrystalline structure by SPEX 8000D shaker mill. The as -milled powders were consolidated by conventional sintering and spark plasma sintering methods. Results: The as -milled grain size of 10 nm increased to 450 nm and 1.5 mu m after conventional sintering at 1000 and 1100 degrees C, respectively, which shows that nanocrystalline CoCrFeNi alloy does not remain thermally stable after long temperature exposures at elevated temperatures. After consolidation of as -milled powders by SPS at 1100 degrees C, the grain size of the HEA was retained around 353 nm. This striking thermal stability of HEA is correlated with high heating rates and lower sintering duration by SPS, and the Zener pinning of the boundaries by nano -sized Cr-rich carbide phases. Accordingly, the as -milled hardness of the CoCrFeNi HEA reduced from 4.6 GPa to 2.1 GPa after conventional sintering at 1100 degrees C due to the significant grain growth, while the enhance hardness of 3.6 GPa was maintained after consolidation with SPS at 1100 degrees C. Conclusion: The findings suggest that as -milled CoCrFeNi HEA is not thermally stable particularly at high homologous processing temperatures. Consolidation with spark plasma sintering technique at 1100 degrees C provided higher density and higher thermal stability with a retarded grain growth of around 353 nm.
dc.identifier.doi10.17341/gazimmfd.1344942
dc.identifier.issn1300-1884
dc.identifier.issn1304-4915
dc.identifier.issue4
dc.identifier.scopus2-s2.0-85195680588
dc.identifier.scopusqualityQ2
dc.identifier.trdizinid1257614
dc.identifier.urihttps://doi.org/10.17341/gazimmfd.1344942
dc.identifier.urihttps://search.trdizin.gov.tr/tr/yayin/detay/1257614
dc.identifier.urihttps://hdl.handle.net/20.500.12885/5377
dc.identifier.volume39
dc.identifier.wosWOS:001238308500010
dc.identifier.wosqualityQ3
dc.indekslendigikaynakWeb of Science
dc.indekslendigikaynakScopus
dc.indekslendigikaynakTR-Dizin
dc.language.isoen
dc.publisherGazi Univ, Fac Engineering Architecture
dc.relation.ispartofJournal of The Faculty of Engineering and Architecture of Gazi University
dc.relation.publicationcategoryMakale - Uluslararası Hakemli Dergi - Kurum Öğretim Elemanı
dc.rightsinfo:eu-repo/semantics/openAccess
dc.snmzWOS_KA_20260207
dc.subjectHigh entropy alloys
dc.subjectMechanical alloying
dc.subjectConventional sintering
dc.subjectSpark plasma sintering
dc.subjectMicrostructural characterization
dc.titleInvestigation of the effects of conventional sintering and spark plasma sintering methods on the microstructural properties and hardness of nanostructured CoCrFeNi high entropy alloy
dc.title.alternativeGeleneksel sinterleme ve spark plazma sinterleme yöntemlerinin nanokristal yapılı CoCrFeNi yüksek entropili alaşımın mikroyapısal özellikleri ve sertliği üzerine etkilerinin araştırılması
dc.typeArticle

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