Correlation Between Structure, Microstructure, and Magnetic Properties of AlCoCrFeNi High-Entropy Alloy

This study explores the crystal structure, microstructure and magnetic phase evolution of the AlCoCrFeNi high-entropy alloy (HEA), highlighting its potential for applications requiring tailored magnetic properties across diverse temperatures. Electron microscopy and X-ray diffraction revealed that the as-cast alloy’s microstructure comprises equiaxed grains with branching dendrites, showing compositional variations between interdendritic regions enriched in Al and Ni. Temperature-induced phase transformations were observed above room temperature, transitioning from body centered cubic (BCC) phases (A2 and B2) to a predominant FCC phase at higher temperatures, followed by recrystallization of the A2 phase upon cooling. Magnetization measurements showed a drop near 380 K, suggesting the Curie temperature of BCC phases, a peak at 830 K attributed to optimal magnetic alignment in the FCC phase, and a sharp decline at 950 K marking the transition to a paramagnetic state. Magnetic moment calculations provided insights into magnetic alignment dynamics, while low-temperature analysis highlighted the alloy’s magnetically soft nature, dominated by ferromagnetic contributions from the A2 phase. These findings underscore the strong interdependence of microstructural features and magnetic behavior, offering a foundation for optimizing HEAs for temperature-sensitive scientific and industrial applications.