FORMATION OF NI(100)-AL SURFACE ALLOY

Early studies of the growth of Ni3Al(100) on a Ni(100) surface reporte d that an alloy extending to some depth was formed, In a series of stu dies undertaken using Low and Medium Energy Ion Scattering it has been found that there is evidence for the formation of a surface alloy ext ending to a depth of 2 to 3 atomic layers. A stable c-(2 x 2) structur e was observed which, from MEIS measurements it was determined that 0. 5 ML Al was incorporated into the first three 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 5 % Al observed on the second layer which is consistent with Ni3Al(100) termination.