Influence of gallium addition on the magnetic properties of MnAl alloy

The MnAl alloy has the potential to be used in the automotive industry as a permanent magnet due to its good magnetic properties such as high saturation magnetization, large theoretical (BH)max and high Curie temperature. However, this alloy suffers from brittleness and being metastable. In this work, density functional theory (DFT) with a supercell approach was employed to investigate the magnetic and electronic properties of L10 Mn50Al50-xGax structures. The theoretical lattice parameters are in good agreement with the experimental data, with differences within 2%. Their thermodynamic stability was evaluated from the heats of formation. The heats of formation showed that Ga compromised the thermodynamic stability of MnAl due to an increase in heats of formation. Moreover, the magnetic moment was enhanced as the concentration of Ga increased, indicating that the magnetic strength is enhanced. The Mn 3d contributed more towards the magnetic moment as compared Al and Ga. These findings will positively impact the development of permanent magnets for electric vehicles.