Precipitation behavior of AlxCoCrFeNi high entropy alloys under ion irradiation

Abstract

Materials performance is central to the satisfactory operation of current and future nuclear energy systems due to the severe irradiation environment in reactors. Searching for structural materials with excellent irradiation tolerance is crucial for developing the next generation nuclear reactors. Here, we report the irradiation responses of a novel multi-component alloy system, high entropy alloy (HEA) AlxCoCrFeNi (x = 0.1, 0.75 and 1.5), focusing on their precipitation behavior. It is found that the single phase system, Al0.1CoCrFeNi, exhibits a great phase stability against ion irradiation. No precipitate is observed even at the highest fluence. In contrast, numerous coherent precipitates are present in both multi-phase HEAs. Based on the irradiation-induced/enhanced precipitation theory, the excellent structural stability against precipitation of Al0.1CoCrFeNi is attributed to the high configurational entropy and low atomic diffusion, which reduces the thermodynamic driving force and kinetically restrains the formation of precipitate, respectively. For the multiphase HEAs, the phase separations and formation of ordered phases reduce the system configurational entropy, resulting in the similar precipitation behavior with corresponding binary or ternary conventional alloys. This study demonstrates the structural stability of single-phase HEAs under irradiation and provides important implications for searching for HEAs with higher irradiation tolerance.

Outstanding radiation resistance of tungsten-based high-entropy alloys

“…Other studies show results in the same direction, with HEAs improving radiation tolerance in both fcc and BCC structures. 18,[26][27][28][29][30] Very recently, W-based quinary HEAs with diverse composition have been synthesized as potential materials for fusion applications. The authors observed the formation of Ti carbides and laves phases at large W concentrations.…”

On Lattice Distortion in High Entropy Alloys

“…Since first proposed in 2004, high entropy alloys (HEAs) or multicomponent complex alloys, which comprise at least five different elements in an equal or near-equal atomic fraction, have been attracting a great deal of research interest (Cantor et al, 2004;Yeh et al, 2004;Ye et al, 2016b;Miracle and Senkov, 2017). Many attractive mechanical and physical properties were reported from various HEAs, such as the combined high strength and ductility from CoCrFeMnNi (Li et al, 2016), the exceptional damage tolerance from CoCrNi and CoCrFeMnNi at cryogenic temperatures (Gludovatz et al, 2014(Gludovatz et al, , 2016Zhang et al, 2015b), high ion irradiation resistance (Zhang et al, 2015a;Yang et al, 2016), and the superb specific hardness from Al 20 Li 20 Mg 10 Sc 20 Ti 30 (Youssef et al, 2015). At the fundamental level, these promising properties could be attributed to the unique local atomic structure of HEAs.…”

Effect of Heat Treatment on the Phase Composition, Microstructure and Mechanical Properties of Al0.6CrFeCoNi and Al0.6CrFeCoNiSi0.3 High-Entropy Alloys

“…By contrast, Cr is distributed more uniformly in both brighter, coarser columnar grains and in darker areas. The brighter, coarser columnar grains and the bright fine dendrites in the darker areas exhibit the FCC crystal structure according to the references [12,29], determined by transmission electron microscopy. The dark fine dendrites exhibit the BCC crystal structure [12,17].…”

“…the FCC crystal structure according to the references [12,29], determined by transmission electron microscopy. The dark fine dendrites exhibit the BCC crystal structure [12,17].…”