The neutron scattering experiment on Al0.80Mn0.20 liquid alloy confirmed that the effective spin of Manganese atoms had a mean value around 1 and that the Manganese could exist in two states of different magnetic moments. By minimizing the energy of the spin flip, we demonstrated the fact that Manganese appears in Al1−xMnx alloys as a mixture of Manganese atoms of spin 1/2 and 3/2 in proportions equal to 7/12 and 5/12, respectively. The Manganese atoms with one spin value different of zero may be considered as a binary alloy (B. Grosdidier, A. Ben Abdellah, K. Bouziane, S. M. Mujibur Rahman and J. G. Gasser, Phil. Mag. 93 no 26 (2013) p.3576.) owing to the spin dependence of the exchange and correlation. In this work, we treated Manganese with its two spin values as a quaternary alloy. Consequently, in our calculations, we treated Al–Mn as five component alloys. This allowing us to extend the Faber Ziman formalism originally designed for a binary alloy to a five-component formalism. Our theoretical results are in fairly good agreement with our experimental values which validates the assumptions of our model.