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The Oxidation of an electro-deposited nanocrystalline Cu (nc Cu) and a conventional coarse-grain Cu (cg Cu) was investigated at 30-800 • C under 1 atm of oxygen. Both Cu samples formed external scales of copper oxide (Cu 2 O+CuO). At the lower temperature (30-300 • C) the very slow oxidation rates of both the nc and cg Cu might be attributed to the formation of a protective Cu 2 O surface layer. However at the higher temperature (300-700 • C), oxidation rates of the nc Cu were obviously faster than those of the cg Cu, which was attributed to faster diffusion of various species along grain boundaries both in the metal and in the scale. In particular, the scale grew faster on the nc Cu by means of not only rapid external oxidation as a result of outward diffusion of Cu-ions but also a significant contribution from inward diffusion of oxygen along the grain boundaries in the scales. Compared with the cg Cu, dissolved O 2 in the nc Cu may have a certain effect on the faster oxidation of the nc Cu. Above 700 • C, the difference seemed to disappear as a result of the ineffectiveness of grain-boundary diffusion.

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It is well known that to increase rotational velocity is one of the effective measures to increase total pressure ratio. With increasing velocity, under the condition of transonic flow, the obvious effect of maximum camber location on aerodynamics performance of compressor blades especially in the supersonics zone can be found. In order to reduce the blade losses and to improve the blade design methodology it is necessary to study this complex flow mechanism. This paper describes only the influence of relative maximum camber location on aerodynamics performance, mainly adiabatic efficiency. As an example an axial fan was designed and calculated by the methodologies developed at the Institute of Engineering Thermophysics, Chinese Academy of Sciences.

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