Vanadium-cobalt-iron alloys

Vanadium—Cobalt-Iron Alloys. V—Co—Fe permanent-magnet alloys also are ductile. A common commercial ahoy, Vicahoy I, has a nominal composition 10 wt % V, 52 wt % Co, and 38 wt % Fe (Table 10). Hard magnetic properties are developed by quenching from 1200°C for conversion to bcc a-phase foUowed by aging at 600°C (precipitation of fee y-phase). The resulting properties are isotropic, with ca kJ/m ... 

Ray] Raynor, G.V., Rivlin, V.G., Phase Equilibria in Iron Ternary Alloys. 10. Critical Evaluation of Constitution of Cobalt-Iron-Vanadium System , Int. Met. Rev., 28(4), 211-227 (1983) (Phase Diagram, Phase Relations, Review, 29)... 

Metal implants have become essential biomedical therapeutic tools in a variety of treatments. Metal implants are composed of a variety of metals, depending on function and location. Medical grade stainless steel, chromium-cobalt and titanium alloys are the most frequently used materials. Aluminum, chromium, cobalt, iron, manganese, molybdenum, nickel, titanium, vanadium and zirconium are the most frequent metals used for metal implants [1]. 

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) ... 

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 above considerations will be illustrated by the simultaneous determination of manganese and chromium in steel and other ferro-alloys. The absorption spectra of 0.001 M permanganate and dichromate ions in 1M sulphuric acid, determined with a spectrophotometer and against 1M sulphuric acid in the reference cell, are shown in Fig. 17.20. For permanganate, the absorption maximum is at 545 nm, and a small correction must be applied for dichromate absorption. Similarly the peak dichromate absorption is at 440 nm, at which permanganate only absorbs weakly. Absorbances for these two ions, individually and in mixtures, obey Beer s Law provided the concentration of sulphuric acid is at least 0.5M. Iron(III), nickel, cobalt, and vanadium absorb at 425 nm and 545 nm, and should be absent or corrections must be made. 

Vanadium Alloys.—Vanadium alloys readily with many metals, including aluminium, cobalt, copper, iron, manganese, molybdenum, nickel, platinum, and tin, also with silicon. These alloys have hitherto received scant attention, and little is known in most cases of the systems produced. 

Although the major use of vanadium, manganese, and cobalt is as alloying metals with iron in making specialty steels, chromium is widely used as a plating metal because it is highly resistant to corrosion. Of even greater importance is its use in stainless steels that will be addressed in the next section. 

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