High-Temperature Mechanical Properties and Fracture Mechanisms of FeNiCo(AlSi)ₓ High-Entropy Alloys

Zhe Li

doi:10.6919/ICJE.202604_12(4).0019

Authors

Zhe Li

DOI:

https://doi.org/10.6919/ICJE.202604_12(4).0019

Keywords:

High-entropy Alloys; FCC-to-BCC Phase Transformation; High-temperature Mechanical Properties; Fracture Mechanisms; Dynamic Strain Aging.

Abstract

High-entropy alloys(HEAs)have attracted considerable attention as next-generation structural materials owing to their exceptional combination of mechanical properties and elevated-temperature stability.In this study,we systematically investigated the high-temperature microstructural evolution,compressive and tensile mechanical behavior,and fracture mechanisms of FeNiCo(AlSi)ₓ(x=0.1–0.6)HEAs at 400 °C.Ingots were synthesized by vacuum induction levitation melting and homogenized at 1000°C for 4 hours.With increasing AlSi content,a progressive FCC-to-BCC structural transition was confirmed,with the critical two-phase coexistence zone identified near x=0.3.At 400 °C,the x=0.1 alloy exhibited anomalous high-temperature strengthening with a compressive strength of approximately 3075 MPa,attributed to dynamic strain aging and dynamic recovery operating synergistically within the continuous FCC matrix.Alloys with x≥0.3 underwent severe high-temperature embrittlement driven by thermally accelerated B2 phase precipitation,with fracture modes transitioning progressively from ductile dimple rupture to transgranular and intergranular brittle cleavage.The composition x=0.2 demonstrated the most favorable overall high-temperature mechanical performance,providing critical design guidelines for FeNiCo-based structural applications in elevated-temperature service environments.

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