Oxygen induced segregation of aluminum to α-Cu–Al(1 0 0) alloy surfaces studied by low energy ion scattering and X-ray photoelectron spectroscopy

The effect of annealing temperature on the surface composition of α-Cu–Al(1 0 0) alloys for aluminum concentrations of 5, 12 and 17 at% was investigated using X-ray photoelectron spectroscopy (XPS) and low energy ion scattering (LEIS). Two initial states of the sample surfaces were examined: sputter-cleaned and oxidized. The effect of annealing temperature on segregation is different for sputter-cleaned and oxidized samples. Aluminum preferential sputtering and strong oxygen induced aluminum segregation were detected on all examined samples. Whilst for the sputter-cleaned surfaces a small thermal induced segregation was observed, the combination of annealing and oxygen exposure resulted in aluminum enrichment in the 100–300% range relative to the bulk concentration. The segregation rate is proportional to the aluminum concentration for sputter-cleaned surfaces and displays a maximum for the oxidized α-Cu–Al(12 at.%)(1 0 0) surface.