Vanadium-base alloys

J.H. Park and G. Dragel, Development of Aluminide Coatings on Vanadium-Base Alloys in Liquid Lithium, Eusion Reactor Materials Semiannual Progress Report for the Period Ending, DOE/ER-0313/13, 1993, pp.405-410. 

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. 

Austenitic steels containing titanium or niobium as stabilizing elements tend to absorb carbon from sodium and they withstand decarburization by liquid lithium, thus suppressing a carbon transfer, which might be caused by the presence of vanadium based alloys. 

Vanadium based alloys in lithium environment for fusion reactors. 

Loop Tests Loop test installations vary widely in size and complexity, but they may be divided into two major categories (c) thermal-convection loops and (b) forced-convection loops. In both types, the liquid medium flows through a continuous loop or harp mounted vertically, one leg being heated whilst the other is cooled to maintain a constant temperature across the system. In the former type, flow is induced by thermal convection, and the flow rate is dependent on the relative heights of the heated and cooled sections, on the temperature gradient and on the physical properties of the liquid. The principle of the thermal convective loop is illustrated in Fig. 19.26. This method was used by De Van and Sessions to study mass transfer of niobium-based alloys in flowing lithium, and by De Van and Jansen to determine the transport rates of nitrogen and carbon between vanadium alloys and stainless steels in liquid sodium. 

Aircraft turbines in jet engines are usually fabricated from nickel-based alloys, and these are subject to combustion products containing compounds of sulphur, such as S02, and oxides of vanadium. Early studies of the corrosion of pure nickel by a 1 1 mixture of S02 and 02 showed that the rate of attack increased substantially between 922 K and 961 K. The nickel-sulphur phase diagram shows that a eutectic is formed at 910 K, and hence a liquid phase could play a significant role in the process. Microscopic observation of corroded samples showed islands of a separate phase in the nickel oxide formed by oxidation, which were concentrated near the nickel/oxide interface. The islands were shown by electron microprobe analysis to contain between 30 and 40 atom per cent of sulphur, hence suggesting the composition Ni3S2 when the composition of the corroding gas was varied between S02 02 equal to 12 1 to 1 9. The rate of corrosion decreased at temperatures above 922 K. 

Commercial alloys composition, nomenclature. A simple and general way of identification of a commercial alloy (or of a group of similar alloys) consists of a label which gives (as rounded values) the mass% contents of the main components indicated by their chemical symbols. The alloy, for instance, Ti-6A1-4V, is a titanium-based alloy typically containing 6 mass% aluminium and 4 mass% vanadium. 

X.P Song, P. Pei, PL. Zhang, G.L. Chen, The influence of alloy elements on the hydrogen storage properties in vanadium-based solid-solution alloys, J. Alloys Compd. 455 (2008) 392-397. 

The titanium-base alloys are considerably stronger than aluminum alloys and superior to most alloy steels in several respects. Several types are available. Alloying metals include aluminum, vanadium, tin, copper, molybdenum, and chromium. 

A major commercial use of vanadium has been in steel production (ca. 85% of vanadium production). Vanadium steel, vhich contains 0.1-3% vanadium is tough, strong and heat-resistant, and vithstands strain, vibration and shock. The second largest use area is in nonferrous alloys and nickel-based superalloys for the aerospace industry. Other applications are vanadium containing alloys for batteries and grain refining of aluminum alloys ( 9% of the vanadium production). 

The steel industry accounts for over 90% of the present Free World demand for vanadium, and increasing demand in steel applications is responsible for most of the projected growth. Vanadium is used also as an alloying element in titanium-base alloys and as vanadium catalysts by the chemical industry. Table 14.1 displays estimated vanadium usage in 1973 by major end use for the Free World. 

In steel applications, vanadium is used in the production of KSLA steels, tool and die steels, open die forgings and to some extent as a strengthening agent in plain carbon steels. The titanium industry employs vanadium as an alloy addition to titanium-base alloys used principally in air-frame and gas... 

Refractory metals are used as carbide formers (vanadium) in alloys that contain insufficient chromium to form a protective layer of Cr203 (M0O3 or WO3 in Mo or W containing alloys) or as solution strengthening elements in Co-based alloys (Mo or W) [8]. 

The constitution of many ferritic steels includes chromium and vanadium as basic alloying elements. Knowledge of the phase diagram and thermodynamic properties of the Cr-Fe-V system is essential to imder-stand the behavior of such iron-based alloys. 

Zup] Zupp, R.R., Stevenson, D.A., Statistical Thermodynamics of Carbon in Ternary Austenitic Iron-Base Alloys , Trans. AIME, 242, 862-869 (1968) (Thermodyn., Theory, 35) [1969Ebe] Ebeling, V.R., Wever, H., Contribution to the Cognition of the Iron Comer of the System Iron-Vanadium-Carbon (in German), Arch. Eisenhuettenwes., 40(7), 551-555 (1969) (Phase Diagram, Phase Relations, Thermodyn., Experimental, Kinetics, 26)... 

Per] Perepletchikov, E.F., Ryabtsev, I.A., Vasil ev, V.G., Heinze, H., Stmcture and Properties of High-Carbon High-Vanadium Iron-Base Alloys for Surfacing , Met. Sci. Heat Treat., 45(5—6), 193—196 (2003) (Morphology, Phase Relations, Experimental, Meehan. Prop., 8)... 

Vanadium, niobium, tantalum and molybdenum and their alloys have demonstrated good corrosion resistance in liquid Pb-Li [8]. These materials have dissolution rates in the range 0.001 to 0.004 g/m /day at 645 C [8], which is far superior to the performance of Fe-based alloys. However, the cost associated with many of these materials would make their application impractical for a full-scale reactor. 

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