Composition dependence of topological and chemical orders in liquid Al1-x(Mny(FeCr)1-y)xalloys by neutron diffraction

The composition dependence of the topological order in liquid Al 1-x M x (M=Mn or FeCr) alloys was studied by measuring the neutron structure factors of alloys Al 1-x (Mn 0.304 (FeCr) 0.696 ) x (x=0.14, 0.2, 0.267 and 0.4). The composition of the 3d metal mixture was chosen in such a way that its average coherent scattering length was equal to that of Al atoms, so that the S NN function was directly available from experiment. Important clues indicating a local icosahedral order have been found in the four liquid alloys. Three other neutron diffraction measurements have been performed with the 40 at.% Al liquid alloy with different Mn to sigma -FeCr atomic ratios, yielding an accurate determination of the three partial pair-correlation functions. The comparison between the local structures of Al 80 M 20 and Al 60 M 40 has shown that the strength of heteroatomic interactions is similar in both alloys, while the first MM and AlAl distances are significantly shorter in Al 60 M 40 .