Chemical analysis of alloys

Chemical analysis of the metal can serve various purposes. For the determination of the metal-alloy composition, a variety of techniques has been used. In the past, wet-chemical analysis was often employed, but the significant size of the sample needed was a primary drawback. Nondestmctive, energy-dispersive x-ray fluorescence spectrometry is often used when no high precision is needed. However, this technique only allows a surface analysis, and significant surface phenomena such as preferential enrichments and depletions, which often occur in objects having a burial history, can cause serious errors. For more precise quantitative analyses samples have to be removed from below the surface to be analyzed by means of atomic absorption (82), spectrographic techniques (78,83), etc. 

Standard Test Methods For Chemical Analysis of Magnesium and Magnesium Alloys, ASTM E-35 to 88, American Society for Testing and Materials, Philadelphia, Pa., 1992. 

Typical chemical analysis of some alloys used in power recovery turbines... 

The objective of this monograph is to include all major studies of metal ions in their aqueous solutions as well as some other important studies in their zerovalent metallic state or in alloys, since the nanoparticles of many of these metals have become too important. Besides, the study of the precipitation of metal ions in aqueous solutions, upon sonication, which has been carried out in our laboratory, would also be discussed. Some of such data include unpublished work. The sequence of metallic ions in this chapter are as they come in the sequence of wet chemical analysis of basic radicals, besides the cationic charge has been kept in mind to make groups and sequences that follow the detailed description. 

R.W.Bridges, "Chemical Analysis of Aluminum," Aluminum Co of America, Pittsburgh, Pa(1941) 7)"Routine Spectrographic Analysis of Aluminum and Magnesium and Their Alloys, Aluminum Co of.America, Pittsburgh, Pa(1944) 8)Kirk Othmer 1 (1947), 595 8a)American Research Insti-... 

Calculated from mass loss measurements. b Found by chemical analysis of aluminium alloys after the runs. 

TABLE 1. Chemical analysis of LaNi5 in an industrial lot of alloy... 

Compositions of alloys and catalysts were determined by chemical analysis of acid-digestcd samples. The values in the table have not been normalized. 

In many laboratories that have access to a nuclear reactor, neutron activation is used for the chemical analysis of rocks, minerals, petroleum, biological tissues, alloys, etc., and the technique is well suited for the determination of the concentrations of trace elements in polymers. Neutron activation analysis was used by Given et al. (1) in their studies of water tree growth in polymeric insulation and by Wu and Chen (2) in their studies of dopant-polymer interactions in MoCl5-dcped polyacetylene films. In this work the principles of the method are described and the possibilities are illustrated by means of measurements carried out on polyethylene. 

Chemical analysis of the solutions after anodic dissolution have shown that the oxidation state of chromium in the dissolution products depends on the alloy composition and, correspondingly, on the potential of alloy dissolution. At potentials less positive than the potential of the onset of pure-chromium passivity breakdown, chromium dissolves from the nickel-based alloys as Cr(III). The alloys with chromium contents of not more than 15% dissolve in this manner in NaCl solution. At higher Ea, chromium from the alloy dissolves, for the most part (about 90%), in the form of Cr(VI). This is true for all alloys in Na2SC>4 (or NaNC>3) solution and for the alloys containing more than 25% chromium in NaCl solution. 

In previous sections we have shown how the structures of elemental materials may be rationalized on the basis of microscopic considerations. Our idea was to build up the free energy of a discrete set of competitors and then to make a free energy comparison between these competitors as a function of temperature and perhaps pressure. We next turn to the analysis of alloy phase diagrams. Here we will have to expand the scope of our previous analysis in order to account for the fact that the presence of more than one chemical constituent will at the very least alter the configurational and vibrational entropy. We define alloy in the present context to include any system in which there is more than one... 

Table 1. Chemical analysis of the as-extruded alloys. Concentrations (in atomic percent) were determined by inductively coupled plasma analysis. Sulfur, oxygen and nitrogen contents were determined by combustion analysis.

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