Electron Diffraction Studies on Oxide Films formed on Metals and Alloys Part 2 Selective Oxidation of Alloys

Surface oxidation products on various alloys due to varying oxidizing conditions within the range of 300–900°C for temperature and 10 -4 –760 mmHg. for air pressure are studied by the electron diffraction method. Alloys studied are copper alloys containing 0.3 % Be, 0.5 % Al, 0.1 % Mg, 7 % Mn and 7 % Ni and that of iron with 13 % Al respectively. The selective oxidation or the phenomenon that the baser component of alloy is oxidized selectively in spite of its much lower content in the mother alloy than the other was found to occur generally in these alloys when the air pressure is sufficiently low and the temperature is high enough. High yield of the secondary electron emission of Be-Cu alloy is concluded to be due to the selective oxidation product BeO having a particular orientation grown on this alloy. An unknown oxide of Ni of a spinel type structure is found on 7 % Ni-Cu alloy.