{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,14]],"date-time":"2026-01-14T20:39:27Z","timestamp":1768423167976,"version":"3.49.0"},"reference-count":30,"publisher":"MDPI AG","issue":"17","license":[{"start":{"date-parts":[[2025,8,30]],"date-time":"2025-08-30T00:00:00Z","timestamp":1756512000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>Complex concentrated alloys (CCAs) have attracted significant attention due to their potential to develop materials with enhanced properties, such as increased hardness and strength. These properties are strongly influenced by the chemical composition and the processing method used. Body-centred cubic (BCC) structures are known to have high hardness but low fracture toughness, whereas face-centred cubic (FCC) structures typically exhibit lower hardness but higher toughness. In this study, Al-Cr-Cu-Fe-Mn-Ni CCAs with three distinct compositions were produced using pressureless sintering. One set of samples was prepared with equiatomic composition (composition E), whereas the compositions of the other two sets were defined based on thermodynamic calculations to obtain sintered samples predominantly formed by BCC (composition B) or FCC (composition F) phases. The samples were characterized using X-ray diffraction, scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, electron backscatter diffraction, density measurements, hardness measurements, and uniaxial compression tests. For all compositions, good agreement was obtained between the phases predicted by thermodynamic calculations and those experimentally detected. In addition, significant differences in the mechanical properties were observed between samples with each composition. The samples with composition B exhibited the highest hardness, but almost no ductility. In contrast, samples with composition F showed the lowest yield strength and hardness, but the highest ductility. Samples with composition E had intermediate values between those of samples B and F. These differences were attributed to differences in the proportions and properties of the BCC and FCC phases in each composition and demonstrate that the mechanical properties of Al-Cr-Cu-Fe-Mn-Ni CCAs can be tailored using compositions defined based on thermodynamic calculations.<\/jats:p>","DOI":"10.3390\/ma18174068","type":"journal-article","created":{"date-parts":[[2025,9,2]],"date-time":"2025-09-02T08:23:38Z","timestamp":1756801418000},"page":"4068","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Tailoring Mechanical Properties of Al-Cr-Cu-Fe-Mn-Ni Complex Concentrated Alloys Prepared Using Pressureless Sintering"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3980-8392","authenticated-orcid":false,"given":"Tiago","family":"Silva","sequence":"first","affiliation":[{"name":"Department of Materials and Ceramic Engineering, CICECO-Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8594-1779","authenticated-orcid":false,"given":"Augusto","family":"Lopes","sequence":"additional","affiliation":[{"name":"Department of Materials and Ceramic Engineering, CICECO-Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2025,8,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Gao, M.C., Yeh, J.W., Liaw, P.K., and Zhang, Y. (2016). High-Entropy Alloys-Fundamentals and Applications, Springer.","DOI":"10.1007\/978-3-319-27013-5"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"448","DOI":"10.1016\/j.actamat.2016.08.081","article-title":"A critical review of high entropy alloys and related concepts","volume":"122","author":"Miracle","year":"2017","journal-title":"Acta Mater."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"177","DOI":"10.1016\/j.actamat.2017.06.027","article-title":"Mapping the world of complex concentrated alloys","volume":"135","author":"Gorsse","year":"2017","journal-title":"Acta Mater."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"299","DOI":"10.1002\/adem.200300567","article-title":"Nanostructured high-entropy alloys with multiple principal elements: Novel alloy design concepts and outcomes","volume":"6","author":"Yeh","year":"2004","journal-title":"Adv. Eng. Mater."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"721","DOI":"10.1016\/j.crhy.2018.09.004","article-title":"From high-entropy alloys to complex concentrated alloys","volume":"19","author":"Gorsse","year":"2018","journal-title":"C. R. Phys."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"685","DOI":"10.3166\/acsm.31.685-698","article-title":"Effect of the substitution of Co by Mn in Al-Cr-Cu-Fe-Co-Ni high-entropy alloys","volume":"31","author":"Chen","year":"2006","journal-title":"Ann. Chim. Sci. Mat."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1468","DOI":"10.1007\/s11661-014-2523-7","article-title":"The Mechanical and corrosion behaviors of as-cast and re-melted AlCrCuFeMnNi multi-component high-entropy alloy","volume":"46","author":"Soare","year":"2015","journal-title":"Metall. Mater. Trans."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Silva, T., and Lopes, A. (2024). Microstructural characterization of AlCrCuFeMnNi complex concentrated alloy prepared by pressureless sintering. Materials, 17.","DOI":"10.3390\/ma17102378"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Silva, T., Sim\u00f5es, P., and Lopes, A. (2024). Hot uniaxial pressing and pressureless sintering of AlCrCuFeMnNi complex concentrated alloy\u2014A comparative study. Materials, 17.","DOI":"10.3390\/ma17225457"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1600726","DOI":"10.1002\/adem.201600726","article-title":"Microstructure, mechanical properties, and oxidation behavior of AlxCr0.4CuFe0.4MnNi high entropy alloys","volume":"19","author":"Rao","year":"2017","journal-title":"Adv. Eng. Mater."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"142495","DOI":"10.1016\/j.msea.2021.142495","article-title":"Effect of Al content on microstructure and mechanical properties of as-cast AlxFeMnNiCrCu0.5 high-entropy alloys","volume":"832","author":"Nguyen","year":"2022","journal-title":"Mater. Sci. Eng. A"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"105","DOI":"10.1016\/j.actamat.2013.09.037","article-title":"Effects of Al addition on structural evolution and tensile properties of the FeCoNiCrMn high-entropy alloy system","volume":"62","author":"He","year":"2014","journal-title":"Acta Mater."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"23","DOI":"10.1016\/j.intermet.2016.06.011","article-title":"Affordable FeCrNiMnCu high entropy alloys with excellent comprehensive tensile properties","volume":"77","author":"Rao","year":"2016","journal-title":"Intermetallics"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"122555","DOI":"10.1016\/j.matchemphys.2019.122555","article-title":"Influence of composition and as-cast structure on the mechanical properties of selected high entropy alloys","volume":"242","author":"Mitrica","year":"2020","journal-title":"Mater. Chem. Phys."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Murty, B.S., Yeh, J.W., and Ranganathan, S. (2014). High-Entropy Alloys, Elsevier Inc.","DOI":"10.1016\/B978-0-12-800251-3.00002-X"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2431","DOI":"10.1016\/j.jmrt.2022.01.141","article-title":"Mechanically alloyed high entropy alloys: Existing challenges and opportunities","volume":"17","author":"Kumar","year":"2022","journal-title":"J. Mater. Res. Technol."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Sharma, V., Kumar, S., and Mallick, A. (2023). Light weight MnTiAlNiFe high-entropy alloy (LWHEA) fabricated by powder metallurgy process: Mechanical, microstructure, and tribological properties. Mater. Today Proc.","DOI":"10.1016\/j.matpr.2023.04.157"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Sharma, N., Alam, S.N., and Ray, B.C. (2019). Fundamentals of Spark Plasma Sintering (SPS): An Ideal Processing Technique for Fabrication of Metal Matrix Nanocomposites, Springer Nature.","DOI":"10.1007\/978-3-030-05327-7_2"},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Su\u00e1rez, M., Fern\u00e1ndez, A., Men\u00e9ndez, J.L., Torrecillas, R., Kessel, H.U., Hennicke, J., Kirchner, R., and Kessel, T. (2013). Challenges and Opportunities for Spark Plasma Sintering: A Key Technology Form a New Generation of Materials, INTECH Open Access Publisher.","DOI":"10.5772\/53706"},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Chen, Y., Liu, P., Dong, Z., Liu, H., Wang, J., Guo, X., Xia, Y., and Wang, Q. (2023). Sintering, microstructure, and mechanical properties of TiTaNbZrHf high-entropy alloys prepared by cold isostatic pressing and pressure-less sintering of hydrides. Materials, 16.","DOI":"10.3390\/ma16051759"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"839","DOI":"10.1007\/s11837-012-0365-6","article-title":"Computational thermodynamics aided high-entropy alloy design","volume":"64","author":"Chuan","year":"2012","journal-title":"JOM"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Li, R., Xie, L., Wang, W.Y., Liaw, P., and Zhang, Y. (2020). High-throughput calculations for high-entropy alloys: A brief review. Front. Mater., 7.","DOI":"10.3389\/fmats.2020.00290"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"434","DOI":"10.1016\/j.jallcom.2016.11.383","article-title":"In the quest of single phase multi-component multiprincipal high entropy alloys","volume":"697","author":"Tazuddin","year":"2017","journal-title":"J. Alloys Compd."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1323","DOI":"10.1016\/j.jct.2011.03.021","article-title":"Calculating all local minima on liquidus surfaces using the FactSage software and databases and the mesh adaptive direct search algorithm","volume":"43","author":"Aimen","year":"2011","journal-title":"J. Chem. Thermodyn."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1016\/j.calphad.2011.06.003","article-title":"Calculating optimal conditions for alloy and process design using thermodynamic and property databases, the FactSage software and the mesh adaptive direct search algorithm","volume":"36","author":"Gheribi","year":"2012","journal-title":"Calphad"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1016\/j.actamat.2018.09.001","article-title":"On the prediction of low-cost high entropy alloys using new thermodynamic multi-objective criteria","volume":"161","author":"Gheribi","year":"2018","journal-title":"Acta Mater."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1016\/j.calphad.2016.05.002","article-title":"FactSage Thermochemical Software and Databases, 2010\u20132016","volume":"54","author":"Bale","year":"2016","journal-title":"Calphad"},{"key":"ref_28","unstructured":"(2024). Powder Diffraction File (PDF) Database 2024, International Centre for Diffraction Data."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1007\/s10853-008-3008-0","article-title":"Review: Liquid phase sintering","volume":"44","author":"German","year":"2009","journal-title":"J. Mater. Sci."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"234","DOI":"10.3390\/met15030234","article-title":"Optimization of Microstructure and Mechanical Properties in Al-Zn-Mg-Cu Alloys Through Multiple Remelting and Heat Treatment Cycles","volume":"15","author":"Peng","year":"2025","journal-title":"Metals"}],"container-title":["Materials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1944\/18\/17\/4068\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T18:35:54Z","timestamp":1760034954000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1944\/18\/17\/4068"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,8,30]]},"references-count":30,"journal-issue":{"issue":"17","published-online":{"date-parts":[[2025,9]]}},"alternative-id":["ma18174068"],"URL":"https:\/\/doi.org\/10.3390\/ma18174068","relation":{},"ISSN":["1996-1944"],"issn-type":[{"value":"1996-1944","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,8,30]]}}}