Effect of grain and phase boundaries on soft magnetic properties of FeCoNiAlSi high-entropy alloys

Abstract The impact of grain and phase boundaries on the magnetic domain structure and soft magnetic properties of the FeCoNi(AlSi)x (0.1 ≤ x ≤ 0.7) high-entropy alloys (HEAs) have been studied in this work. The x = 0.1 alloy with single FCC phase and the x = 0.5 alloy with single BCC phase show obvious grain and phase boundaries, while the x = 0.3 containing FCC plus BCC phase and x = 0.7 alloy containing single BCC phase only present phase boundaries. Besides, The magnetic domains can cross grain and phase boundaries when the exchange coupling interaction is stronger enough. However, the domains are blocked for x = 0.5 alloy due to the strong pinning effect of grain boundaries (GBs). Moreover, the x = 0.1 and x = 0.5 alloys display good statically soft magnetic properties with relatively low coervivity (Hc) and high maximum permeability (μmax), whereas the x = 0.3 and x = 0.7 alloys exhibit good dynamic magnetic parameters with low alternating current (AC) Hc and total loss (Ps).