Cost-effective synthesis and characterization of Fe₂AlB₂ MAB phase

The Fe₂AlB₂ MAB phase features a nanolaminated structure and is notable for its near-room temperature magnetocaloric effect. Fe₂AlB₂ has promising properties but is usually synthesized from costly pure elements. Using cheaper metal oxides is largely unexplored, offering a new route. This work synthesizes Fe₂AlB₂ by combining self-propagating high-temperature synthesis (SHS) and vacuum arc melting (VAM). Fe₂AlB₂ and FeB phases were synthesized by SHS, an energy-efficient method. Before SHS, thermochemical modelling determined the starting molar amounts of the raw materials and predicted reaction propagation. To increase Fe₂AlB₂ concentration, two samples were prepared by adding 50 % and 100 % more aluminium (Al) than required, using the VAM technique. Samples were characterized by elemental, phase, microstructural analyses, and nanoindentation. Fe₂AlB₂ formed in both samples, with phase fractions of 47 wt% and 61 wt% for 50 % and 100 % Al addition, respectively, indicating that increased Al promotes Fe₂AlB₂ formation. Nanoindentation results for the Fe₂AlB₂ phase in the 100 % Al addition sample—hardness of 1249 ± 23 Vickers (12.25 ± 0.22 GPa) and Young's modulus of 284 ± 17 GPa—were consistent with literature. This work provides a promising approach for the low-cost synthesis of Fe₂AlB₂.