Laser/electron beam alloying

Laser and electron beam processing are effective methods for preparing amorphous surface alloys covering conventional crystalline bulk metals... 

As in the case of many metal—alloy systems, weld ductiUty is not as good as that of the base metal. Satisfactory welds can be made in vanadium alloys provided the fusion zone and the heat-affected zone (HAZ) are protected from contamination during welding. Satisfactory welds can be made by a variety of weld methods, including electron-beam and tungsten-inert-gas (TIG) methods. It is also likely that satisfactory welds can be made by advanced methods, eg, laser and plasma techniques (see Lasers Plasma technology). 

Davies, J.A. Collision cascades and spike effects. In Poate, J.M. Foil, G., Jacobson, D.C. (eds.) Surface Modification and Alloying by Laser, Ion, and Electron Beams, pp. 189— 210. Plenum, New York (1983)... 

Another problem limiting the application of nanociystalline materials is prep>aration of nanocrystalline alloys. Currently, the bulk metallic nanomaterials can only be prepared at the laboratory scale, usually by compacting prepared nanocrystalline powders. However, consolidation of the nanopowders into bulk materials needs high temperature and pressure which may considerably coarsen the structure. Because of this difficulty, surface nanocoating has been considered a potential industry application. Nanocrystalline costing are often prepared by chemical vapour deposition (CVD), physical vapour deposition (PVD), electrochemical deposition, electro-spark deposition, and laser and electron beam surface treatment. 

Using laser and/or electron beam welding, components can be produced that combine the (targeted) properties of material (e.g., a mold steel and a highly heat conductive copper base) where needed. This allows many previously structurally desirable but not technically feasible applications of copper-steel composite components. Figure 3.17 shows an injection molding nozzle on which the highly stressed tip and the thread were manufactured from a Co-base alloy. 

The evaporation of a material in vacuum requires a vapor source to support the evaporant and to supply the heat of vaporization while maintaining the material at a temperature sufficiently high to produce the desired vapor pressure. The temperature can be obtained by resistive heating of the vapor source, a crucible or a hearth of a suitably chosen material, or by directly heating the evaporant using a laser or electron beam. For the deposition of multicomponent systems such as alloys. 

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