Nearest-neighbor configurations of Fe atoms in Fe3−xTixAl ordered alloys

Mössbauer spectroscopy and Monte Carlo simulation have been combined to explain the structural and magnetic properties of Fe3−xTixAl alloy system where x = 0.2, 0.45, 0.55, 0.65, 0.75 and 1. Titanium atoms added to Fe3Al alloy occupy FeI sites which leads to a continuous transformation from the D03 structure to the L21 one. It was shown that the six different bcc nearest-neighbor (nn) configurations of Fe atoms are of importance in the whole range of Ti concentrations. Two of them (with 8 and 4 Fe atoms as nn) are magnetic and the remaining ones (with 3, 2, 1, and 0 Fe atoms as nn) are non-magnetic. The relative frequency of occurrence of these configurations depends on Ti concentration and affects the magnetic properties of a sample. The surroundings related with Fe2TiAl Heusler phase appear already for x = 0.45.