Structural, electrical and magnetic properties of icosahedral Al-Co alloys

Abstract

Alloys of the composition Al100-xCox for x approximately=14 are found to be of the nonBravais icosahedral structure when quenched from the melt at a rate of >1*106K s-1. X-ray measurements show the presence of FCC Al as well as the icosahedral phase. Measurements on alloys of different compositions indicate that the icosahedral phase has a stoichiometry of approximately Al4Co. The 57Fe Mossbauer effect spectrum of a sample containing 1 at.% Fe shows a quadrupole split doublet. Mossbauer effect parameters are compared with those for other icosahedral Al86T13Fe (T=Cr,Mn,Fe) alloys. Magnetisation measurements show the icosahedral Al-Co alloy to be a weak paramagnet with a room-temperature susceptibility of chi =1.3*10-6 EMU g-1. The electrical resistivity shows a weak temperature dependence with a minimum at approximately 15K.