Early studies of the growth of Ni3A1(100) on a Ni(100) surface reported that an alloy extending to some depth was formed. In a series of studies undertaken using Low and Medium Energy Ion Scattering it has been found that there is evidence for the formation of a surface alloy extending to a depth of 2 to 3 atomic layers. A stable c-(2 X 2) structure was observed which, from MEIS measurements it was determined that 0.5 ML Al was incorporated into the first Free atomic layers. From LEIS it was possible to confirm that the Al did not form an overlayer and that the surface atomic layer comprised 50% Al. There was less than 59% Al observed on the second layer which is consistent with Ni3Al(100) termination.