A new plasma chemical process has been found that produces tungsten thin films. Using fine powders or precursors as feedstocks, the process vaporizes the feedstocks and then deposits nanometer size grains. The deposition kinetics of structures produced with this technique vary greatly from classical plasma spraying methods. Equiaxed and columnar grains (30-150 nm) are formed instead of splat structures, although the grains may continue to grow after spraying.

The mechanical properties of tungsten-rhenium and tungsten-rhenium-hafnium carbide alloys produced by vacuum plasma spray forming have been evaluated. The results of both tensile and three-point bend tests at room temperature and elevated temperatures will be discussed. In addition, the results of a microstructural analysis will be presented.

Near-net-shape spray forming reduces the cost and complexity of fabricating certain types of structures. Although such components perform adequately as-sprayed, improvements achieved through alloying, thermal treatments, and additional coating steps are often worth pursuing. In tungsten components, for example, additions of rhenium, nickel, or iron can significantly improve material strength and ductility; thermal treatments such as heat treating and hot isostatic pressing can change and densify microstructures; and coating exposed surfaces can improve environmental compatibility. Such improvements in plasma spray formed refractory metal components are presented in this paper.