Oxidation of two-phase Cu-Cr alloys
with different microstructures
with different microstructures
(1. Department of Mechanical Engineering,
Shenyang Institute of Chemical Technology, Shenyang 110021, P.R.China;
2. State Key Laboratory for Corrosion and Protection,
Institute of Metal Research， Chinese Academy of Sciences, Shenyang 110016, P.R.China)
Shenyang Institute of Chemical Technology, Shenyang 110021, P.R.China;
2. State Key Laboratory for Corrosion and Protection,
Institute of Metal Research， Chinese Academy of Sciences, Shenyang 110016, P.R.China)
Abstract: The oxidation of PM Cu-50Cr, MA Cu-40Cr and MS Cu-40Cr alloys at 800 ℃ in 0.1 MPa O2 was studied. The most important difference of their oxidation behaviors is the formation of an exclusive chromia scale on the surface of the MS Cu-40Cr alloy and a continuous chromia layer beneath an outer CuO layer corresponding MA Cu-40Cr alloy, while a complex scale composing of CuO, Cu2O, Cu2Cr2O4 and Cr2O3formed on the PM Cu-50Cr alloy. This result implies that alloy microstructure affects their oxidation behaviors largely. Microcrystalline structure provides numerous diffusion paths for reactive component chromium, shorter diffusion distance and rapid dissolution of Cr-riched second phase. All these favor the exclusive formation of the most stable oxide.
Key words: oxidation; Cu-Cr alloys; powder metallurgy; mechanical alloying; sputtering