Master alloy

Ferro-alloys Master alloys containing a significant amount of bon and a few elements more or less soluble in molten bon which improve properties of bon and steels. As additives they give bon and steel better characteristics (increased tensile sbength, wear resistance, corrosion resistance, etc.). For master alloy production carbothermic processes are used for large-scale ferro-sihcon, ferro-chromium, ferro-tungsten, ferro-manganese, ferro-nickel and metallothermic processes (mainly alumino and sihco-thermic) for ferro-titanium, ferro-vanadium, ferro-molybdenum, ferro-boron. 

Yunfeng Liu, Study on Oxygen-enriched Blowing Antimony White from Lead-antimony Alloy, Master Degree Thesis, Central South University, Changsha, Hunan,... 

A rapid method to determine the calcium content of lead alloys is a Hquid-metal titration using lead—antimony (1%) (9). The end point is indicated by a gray oxide film pattern on the surface of a sohdifted sample of the metal when observed at a 45° angle to a light source. The basis for the titration is the reaction between calcium and antimony. The percentage of calcium in the sample can be calculated from the amount of antimony used. If additional calcium is needed in the alloy, the melt is sweetened with a lead—calcium (1 wt %) master alloy. 

Producing lead—calcium—aluminum alloys is difficult. Calcium and aluminum can be added simultaneously to lead using a calcium (73 wt %)—aluminum (27 wt %) master alloy (11) (see Aluminumand aluminum alloys). Using this method, the calcium and aluminum contents can be precisely controlled. Pressed pellets of metallic aluminum andmetaUic calcium are also used. 

Prior to its addition to the aluminum casting alloys, the strontium metal is usually alloyed into the form of a master alloy. These master alloys are typically 10% Sr—90% A1 or 90% Sr—10% Al, and improve the dissolution and handling characteristics of strontium in the foundry. 

Copper Alloys. Tellurium is alloyed with copper for various purposes. Frequently the tellurium is added to molten copper as a copper teUuride (46.3% Te) master alloy, taking advantage of the peritectic melting point of 1051°C. 

Ferrovanadium can also be prepared by the thermite reaction, in which vanadium and iron oxides are co-reduced by aluminum granules in a magnesite-lined steel vessel or in a water-cooled copper cmcible (11) (see Aluminumand aluminum alloys). The reaction is initiated by a barium peroxide—aluminum ignition charge. This method is also used to prepare vanadium—aluminum master alloys for the titanium industry. 

Zirconium metal is marketed in three forms zirconium-containing silicon—manganese, kon, ferrosiUcon, or magnesium master alloys commercially pure zirconium metal and hafnium-free pure zirconium metal. The use of zkcon for the production of zirconium metal of all three types is ca 5—8% of the total U.S. zkcon consumption. 

Alloys./ A substantial amount of chromic oxide is used in the manufacture of chromium metal and aluminum—chromium master alloys. 

Practical considerations enter into the experimental plan in various other ways. In many programs, variables are introduced at different operational levels. For example, in evaluating the effect of alloy composition, oven temperature, and varnish coat on tensile strength, it may be convenient to make a number of master alloys with each composition, spHt the alloys into separate parts to be subjected to different heat treatments, and then cut the treated samples into subsamples to which different coatings are appHed. Tensile strength measurements are then obtained on all coated subsamples. 

Proprietary alloys are assigned numbers by the AA, AISI, CDA, ASTM, and SAE, which maintains master listings at their headquarters. Handbooks describing the system are available. (Cf. ASTM publication DS-56AC.)... 

Lipson (1943, 1944), who had examined a copper-nickeMron ternary alloy. A few years ago, on an occasion in honour of Mats Hillert, Cahn (1991) mapped out in masterly fashion the history of the spinodal concept and its establishment as a widespread alternative mechanism to classical nucleation in phase transformations, specially of the solid-solid variety. An excellent, up-to-date account of the present status of the theory of spinodal decomposition and its relation to experiment and to other branches of physics is by Binder (1991). The Hillert/Cahn/Hilliard theory has also proved particularly useful to modern polymer physicists concerned with structure control in polymer blends, since that theory was first applied to these materials in 1979 (see outline by Kyu 1993). 

Recently " we propo.sed to describe the nonequilibrium alloy kinetics using the fundamental master equation for probability P of finding the occupation number set... 

Martensitic traasfonnation Master ec[uations Mean field crossover to Ising Mechanical properties Metallic alloys Metallic glasses Metastable alloys Microhardness test Microscopic theory of nucleation... 

Silent chains are similar to roller chains in that each has a master or connecting link to facilitate ease of installation and removal from a machine. They are usually made of high-carbon steel or heat-treated steel alloys. As a result, this type of chain provides trouble-free service for extended periods. 

The reduction may be performed in the presence of an alloying component such as copper or aluminum to obtain a master alloy. Such alloys may also be produced by carbofhermic smelting of the oxide in the presence of the alloying constituent. The carbothermic route constitutes a cheaper mode of production, when making the alloys is the sole objective. 

Alloys of beryllium and of other metals with beryllium are also important. Beryllium-aluminum alloy (62%Be, 38%A1) and beryllium-copper master alloy are both available commercially The incorporation of 2% Be into copper greatly increases the hardness and strength of the metal without reducing its electrical and thermal conductance. This is the single largest use of beryllium. 

Master-alloy production, 23 318-319 Masterbatching, 11 307-308 Master contracts, 24 373-374 Master curves, 21 746-747 uses for, 21 747 Master flowmeters, 11 653 Master Oscillator Power Amplifier (MOPA) configuration, 14 697 Masticatory substance, 12 32 Mastic, for protecting art, 11 410, 411 MAT a cells, 26 453 Matched die molding, 20 117 Material balance problems, 10 748 Material balances, in minerals processing, 16 606... 

Uses. Strontium master alloys are used in Al foundry practice. As an addictive to Al-Si alloys, it enhances mechanical properties and machining performance it modifies the morphology of the eutectic from coarse acicular plates of Si to a fine interconnected fibrous morphology, resulting in higher tensile strength and greatly improved ductility. 

In a centrally located recovery plant for the treatment of oxidic and hydroxidic metal containing waste (dust and sludge) from steel and metal works, including the plating industry, the main problem is the dominating amounts of iron. To avoid a secondary waste problem, special precautions have to be considered to create an iron product. One possibility is a pyro-metallurgical treatment to produce pig iron or a master alloy. 

The price of beryllium oxide powder was 154/kg in 1991. The beryllium content of copper—beryllium master alloy was 352/kg. Pure beryllium powder was priced at 615/kg whereas simple shapes in vacuum hot-pressed material were priced at about 685/kg in 1991. 

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