{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,4]],"date-time":"2026-05-04T07:38:00Z","timestamp":1777880280099,"version":"3.51.4"},"reference-count":29,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2021,9,21]],"date-time":"2021-09-21T00:00:00Z","timestamp":1632182400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["PD\/BD\/143030\/2018"],"award-info":[{"award-number":["PD\/BD\/143030\/2018"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"name":"P2020\/Norte2020","award":["NORTE-08-5369-FSE-000051"],"award-info":[{"award-number":["NORTE-08-5369-FSE-000051"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>Nickel nanocomposites reinforced by carbon nanotubes (Ni-CNTs) are one of the possible candidates for applications in highly demanding industries such as the automotive and aerospace industries. As is well known, one of the limitations on the use of some materials in these applications is thermal stability. Some components in these industries are frequently subjected to high temperatures, which is crucial to understanding their microstructures and, consequently, their mechanical properties. For this reason, the main objective of this research is to understand the microstructural evolution of Ni-CNTs nanocomposites when subjected to heat treatment. The nanocomposites with varying levels of CNT content were produced by powder metallurgy, and unreinforced nickel was used for comparison purposes under the same conditions. The dispersion of CNTs, a critical aspect of nanocomposites production, was carried out by ultrasonication, which already proved its efficiency in previous research. The heat treatments were performed under high vacuum conditions at high temperatures (700 and 1100 \u00b0C for 30 and 120 min, respectively). Microhardness tests analyzed the mechanical properties while the extensive microstructural evaluation was conducted by combining advanced characterization techniques such as scanning electron microscopy (SEM) with electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and high-resolution TEM. The obtained results are promising and show that the presence of CNTs can contribute to the thermal stability of the Ni-CNT nanocomposites produced.<\/jats:p>","DOI":"10.3390\/ma14185458","type":"journal-article","created":{"date-parts":[[2021,9,21]],"date-time":"2021-09-21T22:34:01Z","timestamp":1632263641000},"page":"5458","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Heat-Treated Ni-CNT Nanocomposites Produced by Powder Metallurgy Route"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4798-556X","authenticated-orcid":false,"given":"\u00cdris","family":"Carneiro","sequence":"first","affiliation":[{"name":"DEMM, Department of Metallurgical and Materials Engineering, University of Porto, R. Dr. Roberto Frias, 4200-465 Porto, Portugal"},{"name":"LAETA\/INEGI, Institute of Science and Innovation in Mechanical and Industrial Engineering, R. Dr. Roberto Frias, 4200-465 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4670-4516","authenticated-orcid":false,"given":"S\u00f3nia","family":"Sim\u00f5es","sequence":"additional","affiliation":[{"name":"DEMM, Department of Metallurgical and Materials Engineering, University of Porto, R. Dr. Roberto Frias, 4200-465 Porto, Portugal"},{"name":"LAETA\/INEGI, Institute of Science and Innovation in Mechanical and Industrial Engineering, R. Dr. Roberto Frias, 4200-465 Porto, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2021,9,21]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Tjong, S.C. (2009). Introduction. Carbon Nanotube Reinforced Composites, Wiley-VCH Verlag GmbH & Co. KGaA.","DOI":"10.1002\/9783527626991"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Tjong, S.C. (2009). Carbon Nanotube\u2013Metal Nanocomposites. Carbon Nanotube Reinforced Composites, Wiley-VCH Verlag GmbH & Co. KGaA.","DOI":"10.1002\/9783527626991"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Visakh, P.M., and Morlanes, M.J.M. (2016). Carbon Nanotubes and Their Nanocomposites. Nanomaterials and Nanocomposites: Zero- to Three-Dimensional Materials and Their Composites, Wiley-VCH Verlag GmbH & Co. KGaA. [1st ed.].","DOI":"10.1002\/9783527683772"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"392","DOI":"10.1016\/j.matlet.2016.09.023","article-title":"Molten salt assisted solidification nanoprocessing of Al-TiC nanocomposites","volume":"185","author":"Liu","year":"2016","journal-title":"Mater. Lett."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"138926","DOI":"10.1016\/j.msea.2020.138926","article-title":"The enhanced superplasticity of a 2024 matrix nanocomposite reinforced by TiC particles","volume":"774","author":"Yang","year":"2020","journal-title":"Mater. Sci. Eng. A"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1417","DOI":"10.1016\/j.matpr.2020.02.786","article-title":"Accumulative roll bonding behavior of Al8011\/SiC metal matrix nanocomposites","volume":"27","author":"Lakshmanan","year":"2020","journal-title":"Mater. Today Proc."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Zeng, X., Liu, W., Xu, B., Shu, G., and Li, Q. (2018). Microstructure and Mechanical Properties of Al\u2013SiC Nanocomposites Synthesized by Surface-Modified Aluminium Powder. Metals, 8.","DOI":"10.3390\/met8040253"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"145973","DOI":"10.1155\/2014\/145973","article-title":"Sintering and hardness behavior of Fe-Al2O3 metal matrix nanocomposites prepared by powder metallurgy","volume":"2014","author":"Gupta","year":"2014","journal-title":"J. Compos."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"148","DOI":"10.1179\/174329009X424500","article-title":"Influence of nanosized Al2O3 weight percentage on microstructure and mechanical properties of Al\u2013matrix nanocomposite","volume":"54","author":"Mahboob","year":"2011","journal-title":"Powder Metall."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Mattli, M.R., Shakoor, R.A., Matli, P.R., and Amer Mohamed, A.M. (2019). Microstructure and Compressive Behavior of Al\u2013Y2O3 Nanocomposites Prepared by Microwave-Assisted Mechanical Alloying. Metals, 9.","DOI":"10.3390\/met9040414"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"119","DOI":"10.1016\/j.matlet.2019.01.120","article-title":"Uniformly dispersed Y2O3 nanoparticles in nanocrystalline copper matrix via multi-step ball milling and reduction process","volume":"242","author":"Huang","year":"2019","journal-title":"Mater. Lett."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"56","DOI":"10.1038\/354056a0","article-title":"Helical microtubules of graphitic carbon","volume":"354","author":"Iijima","year":"1991","journal-title":"Nature"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"725","DOI":"10.1017\/S143192761600057X","article-title":"Microstructural Characterization of Aluminum-Carbon Nanotube Nanocomposites Produced Using Different Dispersion Methods","volume":"22","author":"Viana","year":"2016","journal-title":"Microsc. Microanal."},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Sim\u00f5es, S., Viana, F., Reis, M.A.L., and Vieira, M.F. (2017). Aluminum and Nickel Matrix Composites Reinforced by CNTs: Dispersion\/Mixture by Ultrasonication. Metals, 7.","DOI":"10.3390\/met7070279"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"487","DOI":"10.1016\/j.carbon.2013.04.105","article-title":"A combination of ball milling and high-ratio differential speed rolling for synthesizing carbon nanotube\/copper composites","volume":"61","author":"Yoo","year":"2013","journal-title":"Carbon"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"108","DOI":"10.1016\/j.compositesb.2018.02.033","article-title":"Strength and failure mechanisms of cnt-reinforced copper nanocomposite","volume":"145","author":"Faria","year":"2018","journal-title":"Compos. B Eng."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1800422","DOI":"10.1002\/adem.201800422","article-title":"Influence of Processing Parameters on the Mechanical Properties of HPT-Deformed Nickel\/Carbon Nanotube Composites","volume":"21","author":"Katzensteiner","year":"2019","journal-title":"Adv. Eng. Mater."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"83","DOI":"10.1016\/j.jma.2017.12.003","article-title":"An investigation on the hardness and corrosion behavior of MWCNT\/Mg composites and grain refined Mg","volume":"6","author":"Saikrishna","year":"2018","journal-title":"J. Magnes. Alloys"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"122","DOI":"10.1016\/j.msea.2014.12.065","article-title":"Microstructural thermal stability of CNT-reinforced composites processed by severe plastic deformation","volume":"626","author":"Lasserre","year":"2015","journal-title":"Mater. Sci. Eng. A"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"857","DOI":"10.1038\/s41598-020-57946-3","article-title":"Microstructural evolution during heating of CNT\/Metal Matrix Composites processed by Severe Plastic Deformation","volume":"10","author":"Aristizabal","year":"2020","journal-title":"Sci. Rep."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"15","DOI":"10.1016\/j.carbon.2014.01.013","article-title":"Microstructural and mechanical behavior of multi-walled carbon nanotubes reinforced Al\u2013Mg\u2013Si alloy composites in aging treatment","volume":"72","author":"Kondoh","year":"2014","journal-title":"Carbon"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"261","DOI":"10.1016\/j.matchar.2019.05.017","article-title":"Heat treatment behavior and strengthening mechanisms of CNT\/6061Al composites fabricated by flake powder metallurgy","volume":"153","author":"Chen","year":"2019","journal-title":"Mater. Charact."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Abbas, A., and Huang, S.-J. (2021). Investigating the Hall-Petch Constants for As-Cast and Aged AZ61\/CNTs Metal Matrix Composites and Their Role on Superposition Law Exponent. J. Compos. Sci., 5.","DOI":"10.3390\/jcs5040103"},{"key":"ref_24","doi-asserted-by":"crossref","unstructured":"Carneiro, \u00cd., Fernandes, J.V., and Sim\u00f5es, S. (2021). Investigation on the Strengthening Mechanisms of Nickel Matrix Nanocomposites. Nanomaterials, 11.","DOI":"10.3390\/nano11061426"},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Carneiro, \u00cd., Viana, F., Vieira, F.M., Fernandes, V.J., and Sim\u00f5es, S. (2019). EBSD Analysis of Metal Matrix Nanocomposite Microstructure Produced by Powder Metallurgy. Nanomaterials, 9.","DOI":"10.3390\/nano9060878"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"180","DOI":"10.1017\/S1431927618015064","article-title":"Microstructural Characterization of Carbon Nanotubes (CNTs)-Reinforced Nickel Matrix Nanocomposites","volume":"25","author":"Carneiro","year":"2019","journal-title":"Microsc. Microanal."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Carneiro, \u00cd., and Sim\u00f5es, S. (2020). Effect of Morphology and Structure of MWCNTs on Metal Matrix Nanocomposites. Materials, 13.","DOI":"10.3390\/ma13235557"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Carneiro, \u00cd., Viana, F., Vieira, M.F., Valdemar Fernandes, J., and Sim\u00f5es, S. (2019). Characterization of Ni\u2013CNTs Nanocomposites Produced by Ball-Milling. Metals, 10.","DOI":"10.3390\/met10010002"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1681","DOI":"10.1016\/S0008-6223(00)00301-8","article-title":"Purification and structural annealing of multiwalled carbon nanotubes at graphitization temperatures","volume":"39","author":"Andrews","year":"2001","journal-title":"Carbon"}],"container-title":["Materials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1944\/14\/18\/5458\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T07:02:54Z","timestamp":1760166174000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1944\/14\/18\/5458"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,9,21]]},"references-count":29,"journal-issue":{"issue":"18","published-online":{"date-parts":[[2021,9]]}},"alternative-id":["ma14185458"],"URL":"https:\/\/doi.org\/10.3390\/ma14185458","relation":{},"ISSN":["1996-1944"],"issn-type":[{"value":"1996-1944","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,9,21]]}}}