Auger parameter studies of aluminium-transition metal alloys

Within a general study of transition metal (TM) alloys, the variation of the Auger parameters of Fe-10 at.% Al and Fe-50 at.% Al relative to the pure metal was determined. Initial- and final-state Auger parameters were calculated and related to charge transfer calculations. Iron exhibits almost pure metal behaviour, particularly in Fe10Al, but Al core holes are more poorly screened than in Al metal. Charge transfer inferred from the final-state Auger parameters suggests that Al carries a positive charge consistent with the electronegativity differences of Fe and Al. However, there is no evidence of Fe carrying a corresponding negative charge: furthermore, positive Al charge is inconsistent with the Al initial-state parameter. This suggests, rather, that the Al-sp -Fe-sd bonds in the alloys are less polarizable than Al bonds in the nearly free electron metal, a concept supported by the reduction in Al 2p plasmon satellite intensity on alloying and the increased plasmon energy associated with the enhanced valence electron density. Copyright (C) 2002 John Wiley Sons, Ltd.