Journal
COMPOSITES PART B-ENGINEERING
Volume 210, Issue -, Pages -Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.compositesb.2021.108638
Keywords
Selective laser melting; High-entropy alloy; Nanocomposite; Carbon contents; In-situ carbides; Microstructure; Tensile property; Deformation mechanism
Funding
- Fundamental Research Program of the Korea Institute of Materials Science [PNK5520]
- National Research Foundation of Korea (NRF) - Korea government (MEST) [2019R1A2C1008904]
- National Research Council of Science & Technology (NST), Republic of Korea [PNK5520] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
- National Research Foundation of Korea [2019R1A2C1008904] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)
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The study investigated the effect of carbon content on the microstructure evolution, tensile properties, and deformation mechanisms of high-entropy alloy matrix nanocomposites additively manufactured by selective laser melting. It was found that an increase in carbon content led to enhancements in strength, work hardening rate, and elongation, while also affecting the microstructural features such as nano-sized carbides and average grain sizes. Furthermore, the formation of dislocation networks and deformation twins were observed, contributing to the high back stresses and yield strengths of the samples.
The fabrication of high-entropy alloy (HEA) matrix nanocomposites by additive manufacturing (AM) is challenging due to that the control of defect-low sample having even distribution of reinforcement via AM is extremely hard. In this study, we investigated the effect of carbon content on the microstructure evolution, tensile properties, and deformation mechanisms of C-x(Co20Cr20Fe20Mn20Ni20)(100-x) (x = 0.5, 1.0, and 1.5 at.%) HEA matrix nanocomposites additively manufactured by selective laser melting (hereafter referred to as SLM-built C-HEAs). SLM-built C-HEAs showed epitaxial growth grains, dislocation networks, and nano-sized carbides. In addition, with an increase in carbon content, the number density of nano-sized carbides, and the average grain sizes and columnar widths increased. In addition, the strength, work hardening rate, and elongation of SLM-built C-HEAs were enhanced as the carbon content increased. Dislocation networks in the as-built samples hindered the dislocation motion in the early to later stages of deformation, thus leading to high back stresses in SLM-built C-HEAs. Deformation twins were also formed in the three samples, because the critical stress for twinning was similar to the flow stresses at an early stage of deformation of SLM-built C-HEAs. Further, the yield strengths of SLM-built C-HEAs were predicted using six strengthening mechanisms that considered the microstructural factors. Based on the above findings, we discussed the correlations between the microstructure, mechanical properties, and deformation mechanisms of SLM-built C-HEAs with different carbon contents.
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