Effect of grain size reduction on
high temperature oxidation of
binary two-phase alloys
high temperature oxidation of
binary two-phase alloys
(1. State Key Laboratory for Corrosion and Protection, Institute of Metal Research,
Shenyang 110016, P.R. China;
2. Dipartimento di Ingegneria Chimica e di Processo,
Università di Genova,Genova 16129, Italy)
Shenyang 110016, P.R. China;
2. Dipartimento di Ingegneria Chimica e di Processo,
Università di Genova,Genova 16129, Italy)
Abstract: The effect of grain size reduction on the high temperature oxidation of binary twophase alloys was discussed based on the recent research progress. The results show that for those two-phase alloys with coarse grain prepared by the conventional methods, complex oxide scales are easily formed after oxidation under high oxygen pressure or under oxygen pressure below the stability limit of the less reactive component oxides. On the contrary, for the nano-sized alloys, an exclusive external oxidation of the most reactive component usually occurs during oxidation in air or pure oxygen even for much lower content of the most reactive component. So the gain size reduction is not always beneficial to improve the oxidation resistance of the materials, but exhibits different effects depending mainly on the protective feature of the scales. The transition mechanisms between the different oxidation modes are discussed with respect to the thermodynamic and dynamic aspects.
Key words: two-phase alloy; nanocrystallization; oxidation mode; oxidation resistance