SEGREGATION AND PREFERENTIAL SPUTTERING OF AL ON ALPHA-CU0.82AL0.18(100)

Using 1-2 keV He+ and 1.5-3 keV Ne+ beams, the measurement of the firs t layer composition of alpha-CU0.82Al0.18(100) at room temperature rev eals a slight enrichment of Al on the surface. The enrichment of Al at room temperature also was confirmed by analysis using a 2 keV Li+ bea m. It was found that Al atoms on the surface were preferentially sputt ered for 1-2 keV He+ and 1.5-3 keV Ne+ beams. The surface concentratio n of Al increased with temperature in the range 300-620 K due to the c ombined effect of preferential sputtering, ion beam mixing and Gibbsia n segregation. An equilibrium sputtering model has been developed whic h agrees with Al surface concentrations up to 473 K. However, at highe r temperatures the surface Al concentrations are greater than those pr edicted by the model, indicating that the surface has not reached sput tering equilibrium.