Studies on Oxidation of a Three-Phase Cu-30Ni-20Cr Alloy in Pure O_2

The oxidation behavior of Cu-30Ni-20Cr alloy was studied at 700～900?℃ in pure oxygen.Results show that the alloy is composed of a mixture of three phases, where the α phase with the largest copper and lowest chromium content forms the matrix and the β phase with an intermediate chromium content forms large islands and has a rather large volume fraction,while the γ phase richest in chromium forms isolated particles dispersed in the other two phases.The oxidation kinetics deviates from the parabolic rate law and its instantaneous rate decreases continuously with time more rapidly than required by the parabolic rate law.Cu-30Ni-20Cr alloy is able to form a continuous Cr_2O_3 layer within the alloy to prevent alloy from being oxidized further.