Electron microscopy; proceedings of the Electron microscopy; proceedings of the Stockholm Conference, September, 1956 electronmicrosco00euro Year: 1957 324 A. W. AGAR AND R. S. M. REVELL 600''C. By means of microdiffraction, the two re- stricted directions can be determined to correspond to the direction of [110] of a-brass. (2) Secondary scattering effect. The secondary scattering effect for CuoO is shown in fig. 11. For ZnO, the irrational diffraction spots due to this effect are distributed more densely than those of CuaO. Fig. 12 shows schematically this effect for only the first quarter
Electron microscopy; proceedings of the Electron microscopy; proceedings of the Stockholm Conference, September, 1956 electronmicrosco00euro Year: 1957 324 A. W. AGAR AND R. S. M. REVELL 600''C. By means of microdiffraction, the two re- stricted directions can be determined to correspond to the direction of [110] of a-brass. (2) Secondary scattering effect. The secondary scattering effect for CuoO is shown in fig. 11. For ZnO, the irrational diffraction spots due to this effect are distributed more densely than those of CuaO. Fig. 12 shows schematically this effect for only the first quarter of the electron diffraction image of a-brass. (3) Selective oxidation. For low pressure of oxygen and the temperature under the melting point of zinc, the surface of a-brass becomes rich in copper atoms, because the vapour pressure of zinc is greater than that of copper and the mobility of the copper atom is greater than that of zinc. Accordingly, it results in the formation of CuoO at an initial stage. At the high temperature over the melting point of zinc, 419 C, the zinc atom will easily combine with the oxygen atom, because the zinc atom be- comes easily displaceable in the specimen. Further- more, ;0 has some tendency of reduction by the above high diffusion of zinc or the dissociation itself in vacuo. References 1. BRiJCK, L., Ann. Physik 26, 233 (1936). 2. GoTTSCHE, H.,Z. Physil< 134, 517 (1953). 3. HONJO, Proc. Pins. Soc. Jap. 8, 113 (1953). 4. VON Laue, Ann. Pliysik 26, 55 (1936). 5. Menzer, G.,Z. Krist. A 99, 410 (1938). 6. MiYAKE, S., Sci. Papers Inst. Phys. Cheni. Research 29, 167(1936). 7. Takahashi, N., Rikagal<iikenl<yi4Jo-iho 27, 536 (1939). (In Japanese.) 8. WiLMAN, H., Proc. Roy. Soc. A 64, 329 (1951). The Electropolishing of Aluminium A. W. Agar and R. S. M. Revell Research Laboratory, Associated Electrical Industries Limited, Alclermaston, Berks., and Metropolitan-Vickers Electrical Co. Ltd., Trafford Park, Manchester, 17 When aluminiu
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