HIGH STRENGTH ALLOYS AND METHODS FOR MAKING SAME

摘要

The alloys are comprised of a multiplicity of alternate, microcrystalline or nanocrystalline films of tungsten metal and tungsten compound. The tungsten compound film may be comprised of a tungsten carbide or a tungsten boride. The tungsten films are the primary films. Their characteristics are the high strength, high hardness, high resilience, and high fracture energy. They may be manufactured by a chemical vapor deposition process in which reactive gas flows are rapidly switched to produce alternate films with abrupt hetero-junctions are thereby to produce the useful micro-crystalline habit. The synthesis method allows effective control of critical flaw size. The structure is such that the primary films may be made sufficiently thick so as to assure some desirable ductile behaviour, but sufficiently thin so as to have high yield strength by dint of their microcrystalline size, and as to limit the size of any flaws. The secondary films are made of enough thickness to prevent the epitaxial growth from one primary film to the next-deposited primary film and thin enough so that they can not contain a flaw of critical size.