Abstract

CoCrFeNi is a well-studied face centered cubic (fcc) high entropy alloy (HEA) that exhibits excellent ductility but only limited strength. The present study focusses on improving the strength-ductility balance of this HEA by addition of varying amounts of SiC using an arc melting route. Chromium present in the base HEA is found to result in decomposition of SiC during melting. Consequently, interaction of free carbon with chromium results in the in-situ formation of chromium carbide, while free silicon remains in solution in the base HEA and/or interacts with the constituent elements of the base HEA to form silicides. The changes in microstructural phases with increasing amount of SiC are found to follow the sequence: fcc → fcc + eutectic → fcc + chromium carbide platelets → fcc + chromium carbide platelets + silicides → fcc + chromium carbide platelets + silicides + graphite globules/flakes. In comparison to both conventional and high entropy alloys, the resulting composites were found to exhibit a very wide range of mechanical properties (yield strength from 277 MPa with more than 60% elongation to 2522 MPa with 6% elongation). Some of the developed high entropy composites showed an outstanding combination of mechanical properties (yield strength 1200 MPa with 37% elongation) and occupied previously unattainable regions in a yield strength versus elongation map. In addition to their significant elongation, the hardness and yield strength of the HEA composites are found to lie in the same range as those of bulk metallic glasses. It is therefore believed that development of high entropy composites can help in obtaining outstanding combinations of mechanical properties for advanced structural applications.

Details

Title
Ceramic-reinforced HEA matrix composites exhibiting an excellent combination of mechanical properties
Author
Mehmood, M. Adil 1 ; Shehzad, Khurram 1 ; Mujahid, M. 1 ; Yaqub, Talha Bin 2 ; Godfrey, Andy 3 ; Fernandes, Filipe 4 ; Muhammad, F. Z. 5 ; Yaqoob, Khurram 1 

 National University of Sciences and Technology (NUST), School of Chemical and Materials Engineering (SCME), Islamabad, Pakistan (GRID:grid.412117.0) (ISNI:0000 0001 2234 2376) 
 University of Coimbra, Department of Mechanical Engineering, CEMMPRE - Centre for Mechanical Engineering Materials and Processes, Coimbra, Portugal (GRID:grid.8051.c) (ISNI:0000 0000 9511 4342) 
 Tsinghua University, School of Materials Science and Engineering, Beijing, China (GRID:grid.12527.33) (ISNI:0000 0001 0662 3178) 
 University of Coimbra, Department of Mechanical Engineering, CEMMPRE - Centre for Mechanical Engineering Materials and Processes, Coimbra, Portugal (GRID:grid.8051.c) (ISNI:0000 0000 9511 4342); Polytechnic of Porto, ISEP - School of Engineering, Porto, Portugal (GRID:grid.410926.8) (ISNI:0000 0001 2191 8636) 
 CESAT, Islamabad, Pakistan (GRID:grid.410926.8) 
Publication year
2022
Publication date
2022
Publisher
Nature Publishing Group
e-ISSN
20452322
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2753453082
Copyright
© The Author(s) 2022. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.