Effects of Al content and annealing on the phases formation, lattice parameters, and magnetization of AlxFe2B2(x=1.0,1.1,1.2) alloys

$\mathrm{AlF}{\mathrm{e}}_{2}{\mathrm{B}}_{2}$ is a ferromagnet with the Curie temperature around 300 K and has the potential to be an outstanding rare-earth free candidate for magnetocaloric applications. However, samples prepared from the melt contain additional phases which affect the functional response of the $\mathrm{AlF}{\mathrm{e}}_{2}{\mathrm{B}}_{2}$ phase. We report on the effects of Al content in samples with the initial (nominal) composition of $\mathrm{A}{\mathrm{l}}_{x}\mathrm{F}{\mathrm{e}}_{2}{\mathrm{B}}_{2}$, where $x=1.0$, 1.1, and 1.2 prepared by arc-melting followed by suction casting and annealing. The as-cast $\mathrm{A}{\mathrm{l}}_{x}\mathrm{F}{\mathrm{e}}_{2}{\mathrm{B}}_{2}$ alloys contain $\mathrm{AlF}{\mathrm{e}}_{2}{\mathrm{B}}_{2}$ as well as additional phases, including the primary solidifying FeB and $\mathrm{A}{\mathrm{l}}_{13}\mathrm{F}{\mathrm{e}}_{4}$ compounds, which are ferromagnetic and paramagnetic, respectively, at 300 K. The presence of these phases makes it difficult to extract the intrinsic magnetic properties of $\mathrm{AlF}{\mathrm{e}}_{2}{\mathrm{B}}_{2}$ phase. Annealing of $\mathrm{A}{\mathrm{l}}_{x}\mathrm{F}{\mathrm{e}}_{2}{\mathrm{B}}_{2}$ alloys at 1040 \ifmmode^\circ\else\textdegree\fi{}C for 3 days allows for reaction of the FeB with $\mathrm{A}{\mathrm{l}}_{13}\mathrm{F}{\mathrm{e}}_{4}$ to form the $\mathrm{AlF}{\mathrm{e}}_{2}{\mathrm{B}}_{2}$ phase, significantly reduces the amount of additional phases, and results in nearly pure $\mathrm{AlF}{\mathrm{e}}_{2}{\mathrm{B}}_{2}$ phase as confirmed with XRD, magnetization, scanning electron microscopy, and electronic transport. The values of the magnetization, effective magnetic moment per Fe atom, specific heat capacity, electrical resistivity, and Seebeck coefficient for the $\mathrm{AlF}{\mathrm{e}}_{2}{\mathrm{B}}_{2}$ compound have been established.