By means of single spin flip Metropolis dynamics on the basis of a random site-diluted three-dimensionalIsing model with nearest-neighbor interactions, contributions of ferromagnetic particles Fe and antiferromagnetic particles Mn to magnetic properties and thermodynamic properties of the disordered system are researched. Firstly, the effect of the lattice size and Monte Carlo simulation steps on the thermodynamic quantities is checked, the existence of frustration in the low temperature and transition temperature(freezing temperature and Curie temperature ) are confirmed. Secondly, contributions of ferromagnetic particles Fe and antiferromagnetic particles Mn to the magnetization(magnetic susceptibility) of the disordered system are researched, suggesting that the antiferromagnetic Mn particle plays a crucial role in determining low-temperature magnetization (magnetic susceptibility), whereas the high-temperature magnetization(magnetic susceptibility) is contributed mainly by Fe component. In order to emphasize the role of manganese particles in FeMnAl system, the thermodynamic properties of theFe06-xMnxAl04 alloy series, bcc Fe05Al05alloys and Fe05Mn01Al04alloys are simulated and compared on the basis of a Metropolis dynamics. Through the above simulations, we reveal that the antiferromagnetic Mn particle in the high temperature area can be regarded as nonmagnetic Al particle, but plays a crucial role in determining low-temperature phase transition. In contrast to Mn particle, the high-temperature magnetic properties and thermodynamic properties are determined by Fe contribution.
