Mg-containing alloy

The industrial uses of Mg are too numerous to be described here, and are detailed in Refs i8, 19 25. The uses of Mg powd in pyrotechnics are discussed under Pyrotechnics. Also see Aluminum Containing Alloys in Vol 1,... 

PUCI3, and MgCl2 to form a 50/50 mole % NaCl-CaCl salt phase and a molten Am-Pu-Mg-Ca alloy which is immiscible in the above salt(lO). After cooling, the metal phase is cleaved away from the salt phase and the salt phase is analyzed. Little, if any, Am or Pu remains in the salt phase and the salt residues can be discarded to waste. Metal recovery begins by evaporating magnesium and calcium from the residual metal button at about 800°C in vacuum. The americium can then be distilled away from the plutonium in a vacuum still operated at 1200°C, using yttria ceramic vessels to contain the molten metal fraction. The bottoms fraction contains the plutonium which is recycled back into the main plutonium stream. 

Typically, Be-containing alloys and intermetallic phases have been prepared in beryllia or alumina crucibles Mg-containing products have been synthesized in graphite, magnesia or alumina crucibles. Alloys and compounds containing Ca, Sr and Ba have been synthesized in alumina , boron nitride, zircon, molybdenum, iron , or steel crucibles. Both zircon and molybdenum are satisfactory only for alloys with low group-IIA metal content and are replaced by boron nitride and iron, respectively, for group-IIA metal-rich systems . Crucibles are sealed in silica, quartz, iron or steel vessels, usually under either vacuum or purified inert cover gas in a few cases, the samples were melted under a halide flux . 

TLC spectrophotometry is used to determine zirconium in Mg-Al alloy. For this purpose, the alloy sample (2 g) is dissolved in HNO3 (20 ml, 6 M), and zirconium is extracted in 6 ml of 0.02-M diantipyrilmethane (DAM) solution in chloroform. The extract was concentrated to 0.4 ml and an aliquot (10 p,l) was chromatographed on silica gel LS plate using 4-M HCl -f dimethylformamide (1 2) as the mobile phase. After development, the portion of the sorbent layer containing the zirconium-DAM complex was removed, and the metal was extracted with 6-M HCl. The zirconium present in this solution was determined in the form of a xylenol orange complex (Amax, 540 nm) by spectrophotometry [22]. 

It will be noted that in the Grignard reactions so far described, only bromo- or iodo-compounds are mentioned. Chlorine compounds do not enter so readily into this reaction to induce them to react it is usually necessary to add a crystal of iodine (B., 38, 2759), or mercuric chloride (C., 1907, I., 872), or a previously prepared magnesium solution (B., 38, 1746 C., 1907, I., 455), or a small amount of Gilman s catalyst (Rec., 1928, 47, 19), which is prepared by heating an alloy of Mg containing 12-75% of Cu with about 20% iodine in vacuo. 

Figure 11.7. A. NMR spectra of an Al-Mg alloy containing zinc, showing the signal from the matrix (upper) and from the precipitate, represented by stoichiometric MgnAli2 (lower). The 2 middle spectra show the effect of aging time at 200°C on the relative amounts of matrix and precipitate phases. B. Knight shift of the matrix of binary Mg-Al alloys as a function of aluminium content. C. Knight shift of the precipitate phase in Mg-Al alloys doped with zinc as a function of the Zn content. From Celotto and Bastow (2001) by permission of Elsevier Science.

When a Zn-containing alloy was used to form the composite matrix, the external surface of the growth was covered by a thin layer of ZnO [29]. No ZnAl204 was observed. For these composites, a thin metal layer separating the external ZnO layer from the A1203 matrix was also observed, but it was significantly thinner than the layer found in using Al-Si-Mg alloys. 

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