Mechanical properties and fractographic analyses of FeCo-2V alloy heat-treated around order-disorder transition temperature

The effect of heat treatment on the mechanical properties of FeCo-2V alloy was investi-gated at temperatures slightly above and below its order-disorder transition point with varied holding times and cooling rates. The fracture surface, grain size, and recrystallized microstructure were characterized by SEM and EBSD. The correlation between yield strength and microstructural features was analysed. Yield strength was found to decrease with the elevation of heating temperature, extension of holding time, and decrease in cooling rate. Fast cooling significantly improved the mechanical strength and ductility. The quenched samples exhibited microscopically ductile fracture features with shallow dim-ples on the fractured surface, while the slow-cooled ones displayed brittle microscopic fracture features, regardless of the heating temperature and holding time. The yield strength follows two separate Hall-Petch relationships for samples dominantly in the or-dered and disordered states. Our analyses reveal that the mechanical strength of FeCo-2V alloy is mainly controlled by the grain size, thus it is important to regulate the grain recrystallization and growth during the heat treatment process. (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The effect of heat treatment on the mechanical properties of FeCo-2V alloy was investigated. The study found that the yield strength decreases with increasing heating temperature and holding time, and decreasing cooling rate. Fast cooling improves the mechanical strength and ductility. The microstructural characteristics of the fracture surface differ between quenched and slow-cooled samples.