The thermogravimetric analysis of ternary Cu-40Ni-20Cr alloys with different microstructures was performed in order to study the effect of microstructure change on oxidation behavior of ternary multi-phase alloys. The results show that the casting Cu-40Ni-20Cr alloy is unable to form protective external scale of chromia, but a very irregular and thin continuous layer of chromia formed at the base of the mixed internal region, while mechanical alloying Cu-4QNi-20Cr alloy is able to form an external C-2O-3 layer associated with a wide light zone depleted of chromium. The reduction in the alloy grain size obviously favors the formation of &203 layer on the ternary multi-phase alloy surface

Key words: COPPER ALLOYS, NICKEL ALLOYS, CHROMIUM ALLOYS, MICRO-STRUCTURE, ALLOYING