Refractory metal alloys

Figure Plasma reactor for growing single crystals of refractory metals, alloys and high melting point carbides.

Dispersion devices, ozone, 17 801-802 Dispersion force, 12 4 Dispersion-free solvent extraction, 10 766 Dispersion hardening, 13 501, 502, 527 of refractory metal alloys, 13 528 Dispersion polymerization, 24 156-157 of acrylamide polymers, 1 323 of methacrylic ester polymers, 16 289 Dispersion processing of FEP polymer, 18 314... 

A ZnS insulating layer 114 is deposited on a sensing layer 112 of HgCdTe. A refractory metal, such as tantalum, molybdenum, tungsten, titanium or refractory metal alloys such as titanium/tungsten, is sputter-deposited onto the insulating layer. The structure is connected to... 

Two methods for the evaporation of precursors may be employed - resistance heating and electron beam collision. The first method employs a simple alumina crucible that is heated by a W filament. Temperatures as high as 1,800°C may be reached inside the chamber, which is enough for some metals or metal salts to vaporize. Deposition rates for this method are 1-20 A s . The use of an electron beam to assist in the precursor evaporation results in temperatures on the order of 3,000°C, being more suited for the deposition of refractory metals/alloys and metal oxides such as alumina, titania, and zirconia. Since the temperature of the chamber interior is much higher than the walls, the gas-phase ions/atoms/molecules condense on the sidewalls as well as the substrate this may lead to film contamination as the nonselective coating flakes off the chamber walls. 

Conference on Chemical Vapour Deposition of Refractory Metals, Alloys and Compounds, Gatlinburg, TN, USA, 1967 [79]... 

Schaffhauser AC (ed) (1967) Proceedings of the conference on chemical vapour deposition of refractory metals, alloys and compounds, Gatlinburg, TN, American Nuclear Society, La Grange Park, IL... 

FI. Lavendel, R. A. Perkins, A. G. Elliot, J. Ong investigation of Modified Silicide Coatings for Refractory Metal Alloys with Improved Low pressure Oxidation Behavior AFML-TR-65-344.1965. 

E. Saunders, M. Weinstein, A. I. Mlavsky, Radiant Energy Reactor Technique for the Deposition of SiC onto Quartz Filaments, Proc. Conf. Chemical Vapor Deposition of Refractory Metals, Alloys, and Comp., American Nuclear Society, Hinsdale, IL, 1967, pp. 1X1-21. 

Two major classes of tool materials have been used for FSW of high-temperature materials. Refractory metal alloys, primarily W-25%Re, have been used to successfully weld... 

Vanadium also forms a very stable carbide VC, and carburization of this metal is part of the corrosion reactions of vanadium based alloys contacted with liquid lithium as well as sodium. Vanadium alloys with contents of titanium have an even higher affinity to form solid carbides by absorbing of carbon from liquid metals. In systems in which vanadium titanium alloys and stainless steels are in contact with the same lithium or sodium, carbon migrates from the steel to the refractory metal alloy, thus passing the alkali metal serving as a transport medium The free energies of formation of the alkali acetylides are compared with the values of several metal carbides in Table V. 

Elongation of Cobalt-Base Superalloys Elongation of Nickel-Base Superalloys Ductility of Refractory Metal Alloys... 

Table 245. RUPTURE STRENGTH OF REFRACTORY METAL ALLOYS... 

Table 3.1-108 Typical compositions of commercial refractory metal alloys (in weight percent, analyses of base-metal correspond to metallic purity) [1.118]... 

There is extensive evidence that between 300 and 500 °C, oxide-dispersion-strengthened (ODS) refractory metal alloys (e.g.. Mo—LaaOs and Mo—Y2O3 grades) possess markedly reduced oxidation rates compared to the pure metals [1.133]. In-situ oxidation and evaluation of the binding state reveal that M0O2 dominates over M0O3 both for Mo and Mo-... 

J. Wadsworth, T. G. Nieh,J.J. Stephens Recent advances in aerospace refractory metal alloys. Inter. 1.128 Mater. Rev. 33(3), 131 (1988)... 

Because hafnium has an elevated absorption cross section for thermal neutrons (almost 565 times that of zirconium), it is extensively used for producing nuclear-reactor control rods. On the other hand, hafnium carbide is the most refractory binary composition known, and the nitride is the most refractory of all known metal nitrides m.p. 3310 C). To a lesser extent, hafnium is used in gas-filled and incandescent lamps as an efficient getter for scavenging oxygen and nitrogen, and alloying with iron, titanium, niobium, and other refractory metal alloys. 

Machlin, I. Begley, R.T. WeiserT, E.D. (eds.) (1968) Refractory Metal Alloys, Metallurgy and Technology. Plenum, New York. 

Refractory metals and alloys are generally dissolution-resistant in liquid metals and corrosion is often controlled by reactions with impurity/interstitial elements [13,14,27]. In the case of refractory metal alloys based on niobium or tantalum, the concentration of oxygen in the alloy is an important parameter with respect to corrosion in alkali metals, particularly lithium [34-38]. As little as 300 wppm of oxygen in niobium will induce catastrophic penetration of the niobium by lithium. Interstitial oxygen will also cause penetration of niobium tmd tantalum by sodium or potassium, but the threshold of oxygen concentration is higher. 

It is instructive to note that Stringer (1973) expressed pessimism about the development of oxidation-resistant refractory metal alloys (Nb, Ta, Mo, W) and that Meier (1996) opines that attempts to protect Nb-base compounds by the selective oxidation of Al or Si are fruitless . Although we are not quite that pessimistic, it is clear that successful development of oxidation-resistant Nb-Al intermetallics for high- temperature structural applications will certainly require a truly radical, new approach. 

E.E. Hoffman and R.W. Harrison. 1968. The compatibility of refractory metals with liquid metals. Refractory Metal Alloys Metallurgy and Technology, New York Plenum Press. 

L. Rosenblum, C.M. Scheurmann, and TA. Moss. 1967. Space-power-system material compatibility tests of selected refractory metal alloys with boiling potassium. Symposium on Alkali Metal Coolants-Corrosion Studies and Systems Operating Experience, Vienna, Austria. 

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