Chromium-niobium alloys

Vow] Vowles, M.D.J., West, D.R.F., Precipitation Hardening in Iron-Chromium-Niobium Alloys , J. Iron Steel Inst., 211(2), 147-150 (1973) (Crys. Structure, Morphology, Experimental, Meehan. Prop., 13)... 

Tubes are made either of chromium-nickel or chromium-niobium alloys, and they are expected to last at least for 100,000 hours (more than eleven years). The latest primary reformer designs have dispensed with the furnace altogether, and the process is heated by gases from the secondary reformer. The reforming reaction is always the same... 

The corrosion behaviour of amorphous alloys has received particular attention since the extraordinarily high corrosion resistance of amorphous iron-chromium-metalloid alloys was reported. The majority of amorphous ferrous alloys contain large amounts of metalloids. The corrosion rate of amorphous iron-metalloid alloys decreases with the addition of most second metallic elements such as titanium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, cobalt, nickel, copper, ruthenium, rhodium, palladium, iridium and platinum . The addition of chromium is particularly effective. For instance amorphous Fe-8Cr-13P-7C alloy passivates spontaneously even in 2 N HCl at ambient temperature ". (The number denoting the concentration of an alloy element in the amorphous alloy formulae is the atomic percent unless otherwise stated.)... 

The passive films formed by the addition of sufficient amounts of valve metals to amorphous nickel-valve-metal alloys are exclusively composed of valve-metal oxyhydroxides or oxides such as TaOjCOH) , Nb02(OH) or TajO,. Consequently, amorphous alloys containing strongly passivating elements, such as chromium, niobium and tantalum, have a very high ability... 

Niobium appears to have a slightly beneficial effect on the oxidation resistance of nickel-chromium-base alloys, although at 1 200°C the addition of niobium to Nichrome (Table 7.18) produces a much higher rate constant. Titanium on the other hand appears to have a slightly deleterious effect on oxidation resistance at low temperatures. 

Chromium iron manganese brown spinel, formula and DCMA number, 7 348t Chromium iron nickel black spinel, formula and DCMA number, 7 348t Chromium isotopes, 6 476 Chromium magnesium oxide, 5 583 Chromium manganese zinc brown spinel, formula and DCMA number, 7 348t Chromium-nickel alloys, 77 100-101 Chromium-nickel-iron alloys, 17 102-103 Chromium-nickel stainless steels, 15 563 Chromium niobium titanium buff rutile, formula and DCMA number, 7 347t Chromium(III) nitrate, 6 533 Chromium nitride, 4 668... 

Aluminium-niobium alloys are best produced by the Goldschmidt process. A product which contains about 8 per cent, of aluminium is harder than glass or quartz its density is 7 5.3 A brittle alloy of chromium and niobium is obtained by fusing green chromium oxide and niobium together in the electric furnace.1... 

Ven] Venkatraman, M., Neumann, J.P., The Cr-Nb (Chromium-Niobium) System , Bull. Alloy Phase Diagrams, 7(5), 462-466 (1986) (Crys. Stracture, Phase Diagram, Phase Relations, Thermodyn., Review, Magn. Prop.,, 23)... 

The zirconium alloys used in PWR nuclear components consist of both zirconium-tin alloys and zirconium-niobium alloys. PWRs have historically used Zircaloy-4, which consists of 98.23 weight % zirconium with 1.45% tin, 0.21% iron, 0.1% chromium, and 0.01% hafnium. 

Biocompatible materials that have been successfully used for implantable medical device packaging include titanium and its alloys, noble metals and their alloys, biograde stainless steels, some cobalt-based alloys, tantalum, niobium, titanium-niobium alloys, Nitinol, MP35N (a nickel-cobalt-chromium-molybdenum alloy). 

The important (3-stabilizing alloying elements are the bcc elements vanadium, molybdenum, tantalum, and niobium of the P-isomorphous type and manganese, iron, chromium, cobalt, nickel, copper, and siUcon of the P-eutectoid type. The P eutectoid elements, arranged in order of increasing tendency to form compounds, are shown in Table 7. The elements copper, siUcon, nickel, and cobalt are termed active eutectoid formers because of a rapid decomposition of P to a and a compound. The other elements in Table 7 are sluggish in their eutectoid reactions and thus it is possible to avoid compound formation by careful control of heat treatment and composition. The relative P-stabilizing effects of these elements can be expressed in the form of a molybdenum equivalency. Mo (29) ... 

Stainless Steel There are more than 70 standard types of stainless steel and many special alloys. These steels are produced in the wrought form (AISI types) and as cast alloys [Alloy Casting Institute (ACI) types]. Gener y, all are iron-based, with 12 to 30 percent chromium, 0 to 22 percent nickel, and minor amounts of carbon, niobium (columbium), copper, molybdenum, selenium, tantalum, and titanium. These alloys are veiy popular in the process industries. They are heat- and corrosion-resistant, noncontaminating, and easily fabricated into complex shapes. 

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