Boron alloying element

In addition to these principal alloying elements, which provide soHd solution strengthening and/or precipitation strengthening, wrought alloys may contain small amounts of titanium and boron [7440-42-8J, B, for control of ingot grain size, and ancillary additions of chromium, manganese, and zirconium to provide dispersoids. AH commercial alloys also contain iron and siUcon. 

Low-carbon, low-alloy steels are in widespread use for fabrication-welded and forged-pressure vessels. The carbon content of these steels is usually below 0.2%, and the alloying elements that do not exceed 12% are nickel, chromium, molybdenum, vanadium, boron and copper. The principal applications of these steels are given in Table 3.8. 

Silicon s atomic structure makes it an extremely important semiconductor. Highly purified silicon, doped with such elements as boron, phosphorus, and arsenic, is the basic material used in computer chips, transistors, sUicon diodes, and various other electronic circuits and electrical-current switching devices. Silicon of lesser purity is used in metallurgy as a reducing agent and as an alloying element in steel, brass, and bronze. 

The addition of low concentrations of elements to steel such as manganese, titanium, or boron can greatly enhance the properties of steel. Improved hardness, strength, machinability, and resistance to corrosion can all be improved by alloying. The effect of various alloying elements is provided in TABLE 9-3. 

The basic steel types arc undergoing gradual modifications to adapt the steels to the continuous casting process. This has led to changes in the minor constituents of steel such as boron, nitrogen, titanium, and other alloying elements. 

Boron. Tlii element is added to increase hardenability, hut is effective only when added to fully killed steels. Since only a few thousandths of lfr ol boron usually remains in the steel, evaluation of boron steels is by increased hardennbility rather than chemical content. The hardenahilily chariLcleristtcs ol elements already present in the steel are intensified by boron, making possible alloy ingredient conservation. Although effective with low-carbon sieels, ihe effectiveness of the element decreases as the earhon content increases. 

Metal organic chemical vapor deposition (MOCVD) is a well-established, practical technique for forming simple as well as complex solid state films (130). For binary systems the conventional approach is to use mixtures of the most readily available molecules containing the elements of interest. This approach has been employed to prepare borides of several types. For example, iron-boron alloys have been pre-... 

Boron, an element, occurs in many compounds, including borax, borates, boric acid, and carboxyboranes used in glass, ceramics, detergents, bleaches, fire retardants, disinfectants, alloys, specialty metals, preservatives, pesticides, and fertilizers (Mastromatteo and Sullivan 1994). Boron compounds also constitute an important group of dopants in the semiconductor industry. Dopants alter crystalline substrates electrical conductivities in the manufacturing of diodes, transistors, and capacitors (Lewis 1986). 

Following the successful commercial synthesis of diamond in the 1950s, the second hardest material known, cubic boron nitride, cBN, was introduced to the market in the 1960s and is complementary to diamond. The iron, and its alloying elements, in ferrous materials has a tendency to react chemically with diamond under machining conditions and this can reduce the efficiency of the tool. cBN, however, although not as hard as diamond, does not react chemically with iron and is therefore particularly well suited to machining hard ferrous materials. 

Boron is used as an alloying element for steel. For that reason, the alloy ferroboron, with 20% boron, is manufactured in electrometallurgical processes and used as a raw material. Low boron contents, as low as 0.003% B, have a marked effect on the hard-enability of steels with medium high carbon contents. It leads to hardening through the component section without alloying the steel with expensive elements such as chromium and nickel. Boron steels of this type have been very much utihzed for agricultural machinery. 

Interest in the metal borides is due mostly to the presence of boron in certain steels and its interaction with other alloying elements. An example of other industrial use of borides is the use of titanium borides for the grain refining of aluminium. Thermochemical data for metal borides are, however, virtually non-existent. The reason, again, is the difficulty of finding suitable experimental methods for enthalpy and Gibbs energy determinations. 

The method described was developed by Mortier et al. (38) for the determination of boron in doped zirconium (100, 20, 1 and 0.5 pig/g of boron), in undoped zirconium and in zircaloy. The conditions given can be used for all these materials. For the 100 and 20 f g/g samples, however, shorter irradiation and measuring times may be used and an instrumental determination is feasible if 6 MeV protons are used. Table IV-3 summarises the most important nuclear reactions of zirconium and its impurities or alloying elements with protons. For low boron concentrations Be must be separated chemically from the radionuclides produced. 

Grain refinement during solidification reportedly can also be obtained by additions of reactive elements like alkaline and rare earth elements, such as calcium, barium, yttrium, or nonmetals like Boron [12], In these cases, nuclei for crystallization from the melt are provided by formation of high melting compounds (sometimes intermetallic phases) of these reactive additions with other alloying elements or impurities, particularly oxygen. 

Many alloying elements in Ni-base superalloys are only of small quantities despite their critical contributions to the superalloy s properties and applications. The carbon content is usually from 0.02 to 0.2 wt%, boron from 0.005 to 0.03 wt%, and zirconium from 0.005 to 0.1 wt%. To reproduce these alloys without knowing their original design details, reverse engineering needs to accurately analyze the alloy chemical composition, particularly the quantitative analysis of the critical elements that appear only in trace amounts. 

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