TY - JOUR
T1 - Microstructural Evaluation of Thermal-Sprayed CoCrFeMnNi0.8V High-Entropy Alloy Coatings
AU - Sfikas, Athanasios K.
AU - Kamnis, Spyros
AU - Tse, Martin C. H.
AU - Christofidou, Katerina A.
AU - Gonzalez, Sergio
AU - Karantzalis, Alexandros E.
AU - Georgatis, Emmanuel
N1 - Funding information: The authors would like to acknowledge the support of the UK Research and Innovation (UKRI-IUK) national funding agency. Project grant: 53662 “Design of high entropy superalloys using a hybrid experimental based machine learning approach: Steel sector application”.
PY - 2023/5/28
Y1 - 2023/5/28
N2 - The aim of this work is to improve the understanding of the effect of the cooling rate on the microstructure of high-entropy alloys, with a focus on high-entropy alloy coatings, by using a combined computational and experimental validation approach. CoCrFeMnNi0.8V coatings were deposited on a steel substrate with high velocity oxy-air-fuel spray with the employment of three different deposition temperatures. The microstructures of the coatings were studied and compared with the microstructure of the equivalent bulk high-entropy alloy fabricated by suction casting and powder fabricated by gas atomization. According to the results, the powder and the coatings deposited by low and medium temperatures consisted of a BCC microstructure. On the other hand, the microstructure of the coating deposited by high temperature was more complex, consisting of different phases, including BCC, FCC and oxides. The phase constitution of the bulk high-entropy alloy included an FCC phase and sigma. This variation in the microstructural outcome was assessed in terms of solidification rate, and the results were compared with Thermo-Calc modelling. The microstructure can be tuned by the employment of rapid solidification techniques such as gas atomization, as well as subsequent processing such as high velocity oxy-air-fuel spray with the use of different spray parameters, leading to a variety of microstructural outcomes. This approach is of high interest for the field of high-entropy alloy coatings.
AB - The aim of this work is to improve the understanding of the effect of the cooling rate on the microstructure of high-entropy alloys, with a focus on high-entropy alloy coatings, by using a combined computational and experimental validation approach. CoCrFeMnNi0.8V coatings were deposited on a steel substrate with high velocity oxy-air-fuel spray with the employment of three different deposition temperatures. The microstructures of the coatings were studied and compared with the microstructure of the equivalent bulk high-entropy alloy fabricated by suction casting and powder fabricated by gas atomization. According to the results, the powder and the coatings deposited by low and medium temperatures consisted of a BCC microstructure. On the other hand, the microstructure of the coating deposited by high temperature was more complex, consisting of different phases, including BCC, FCC and oxides. The phase constitution of the bulk high-entropy alloy included an FCC phase and sigma. This variation in the microstructural outcome was assessed in terms of solidification rate, and the results were compared with Thermo-Calc modelling. The microstructure can be tuned by the employment of rapid solidification techniques such as gas atomization, as well as subsequent processing such as high velocity oxy-air-fuel spray with the use of different spray parameters, leading to a variety of microstructural outcomes. This approach is of high interest for the field of high-entropy alloy coatings.
KW - high-entropy alloy coatings
KW - thermal spray
KW - gas atomization
KW - cooling rate
U2 - 10.3390/coatings13061004
DO - 10.3390/coatings13061004
M3 - Article
SN - 2079-6412
VL - 13
JO - Coatings
JF - Coatings
IS - 6
M1 - 1004
ER -