Remarkable thermal stability of nanocrystalline CoCrFeNi high entropy alloy achieved through the incorporation of rare-earth element samarium
Küçük Resim Yok
Tarih
2025
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Elsevier Sci Ltd
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
High entropy alloys (HEAs) with nanocrystalline grain sizes have received significant interest in recent years; however, their microstructural integrity is compromised by a tendency for grain growth due to their high-volume fraction of grain boundaries. Here, nanocrystalline CoCrFeNi with Sm addition was synthesized through mechanical alloying, followed by annealing at temperatures up to 1100 degrees C and for durations of up to 24 h. The results have revealed that the 16 +/- 6 nm as-milled grain size of CoCrFeNi experienced grain coarsening during the annealing process, reaching similar to 1.35 +/- 0.5 mu m and similar to 4.5 +/- 1.1 mu m after 1 and 24 h annealing at 1100 degrees C, respectively. This indicates that the nanocrystalline microstructure of CoCrFeNi lacks thermal stability at elevated temperatures. The average grain size was maintained at 110 nm after 1 h annealing at 1100 degrees C (T/T-m = 0.74) with Sm addition. Furthermore, while large grains (similar to 1.5 mu m) appeared after 24 h of annealing at 1100 degrees C, pockets of nano-sized grains were still present in the microstructure. The resistance to grain growth is ascribed to the presence of rare earth element, Sm, and the formation of Sm-based additional mixed oxide phases (Sm/Cr-O). Consequently, 517.8 +/- 25 HV as-milled hardness of CoCrFeNi decreased dramatically to 221.5 +/- 11 HV due to extensive grain growth but remained elevated at 442.5 +/- 15 HV (84 % of as-milled hardness) with Sm addition after annealing at 1100 degrees C. These findings highlight the potential for optimizing the thermal and mechanical performance of CoCrFeNi HEAs in various applications.
Açıklama
Anahtar Kelimeler
Rare earth element, Samarium, High entropy alloys, Grain growth, Thermal stability, Isothermal annealing, Nanocrystalline
Kaynak
Intermetallics
WoS Q Değeri
Q1
Scopus Q Değeri
Q1
Cilt
178
