ANALYSIS OF PASSIVE FILMS OF Al ALLOYS BY XPS DEPTH PROFILE

An XPS depth profile analysis was made of the passive films on one Al-Mg alloy and two Al-Cu alloys. It was clarified that in the K_2Cr_2O_7 treated passive films on these alloys, a certain amount of Cr_2O_3 is appeared besides the majority of A1_2O_3. Thus the long-time argument about the presence of Cr_2O_3 in now settled. It was also observed that in the passive films obtained by treatment with N_2-con-taining passivation agent, some A1N and metallic complexes are detected in addition to A1_2O_3. Futhermore, No Cu is signaled in the passive film on two Al-Cu alloys obtained by either K_2Cr_2O_7 or N_2-containing passivation agent, and Cu is shielded by the passive film. It is interesting that a definite Mg peak may be observed on these two passive films although Mg content in Al-Cu alloy is very low, but disappeared after sputtering 5 min.