Metal Structures and Alloys

Brooks, H., in Electronic Structure and Alloy Chemistry of Transition Metals (P. A. Beck, ed.). Wiley, New York, 1963. [Russian transl. p. 9.]... 

Basic information concerning the mechanism of skeletal rearrangement was provided by labeling experiments and kinetic studies. The use of specifically prepared catalysts, such as metal films and alloys, and structure sensitivity studies supplied additional data. The information resulted in establishing two basic processes the bond shift and the cyclic mechanisms.151-154... 

Clusters and alloys are molecular species that may show different catalytic activity, selectivity and stability than bulk metals and alloys. Small metal clusters and alloy clusters have been studied reeendy for potential use as catalysts, ceramic precursors, and as thin films. Several fundamental questions regarding such clusters are apparent. How many atoms are needed before metallic properties are observed How are steric and electronic properties related to the number, type and structure of such clusters Do mixed metal clusters behave like bulk alloy phases ... 

The electro-catalytic oxidation of hydrogen, and reduction of oxygen, at carbon supported platinum based catalysts remain essential surface processes on which the hydrogen PEM fuel cell relies. The particle size (surface structure) and promoting component (as adsorbate or alloy phases) influence the activity and tolerance of the catalyst. The surface chemical behavior of platinum for hydrogen, oxygen, and CO adsorption is considered, in particular with respect to the influence of metal adsorbate and alloy components on close packed and stepped (defect) platinum surfaces. Dynamical measurements (employing supersonic molecular beams) of the... 

The application of such linguistic rules presupposed (as was also remarked above) classes of substances that were already distributed into the five principal types of compounds (column II-VI). This distribution and, a fortiori, the establishment of these five orders of compounds, were a matter of neither linguistic laws or derivations nor formal classificatory rules. Rather, they were classificatory distinctions, distributions, and arrangements resting on chemical assumptions and convictions held by the authors of the Methode. As was shown in chapter 9, the core of these assumptions and convictions developed in the course of the eighteenth century. It was in particular the traditional clusters of classes around the conception of neutral salts and that around the conception of metals, metal calces, and alloys that provided the structure within which systematically coordinated names could be elaborated. 

Mordike, B.L. Kainer, K.U. (eds.) (1998) Magnesium Alloys and Their Applications. Wiley, Wdnheim. Rokhlin L.L. (2002) Magnesium Alloys Containing Rare-Earth Metals Structure and Properties. CRC Press, Boca Raton, FL. 

Metals A and B form an alloy or solid solution. To take a hypothetical case, suppose that the structure is simple cubic, so that each interior atom has six nearest neighbors and each surface atom has five. A particular alloy has a bulk mole fraction XA = 0.50, the side of the unit cell is 4.0 A, and the energies of vaporization Ea and Eb are 30 and 35 kcal/mol for the respective pure metals. The A—A bond energy is aa and the B—B bond energy is bb assume that ab = j( aa + bb)- Calculate the surface energy as a function of surface composition. What should the surface composition be at 0 K In what direction should it change on heaf)pg, and why ... 

W. B. Pearson, Handbook oJEattice Spacings and Structures of Metals and Alloys, International Series on MetalPhysics and Physical Metallurgy, Pergamon Press, New York, 1958, p. 130. 

Structural Properties at Low Temperatures It is most convenient to classify metals by their lattice symmetiy for low temperature mechanical properties considerations. The face-centered-cubic (fee) metals and their alloys are most often used in the construc tion of cryogenic equipment. Al, Cu Ni, their alloys, and the austenitic stainless steels of the 18-8 type are fee and do not exhibit an impact duc tile-to-brittle transition at low temperatures. As a general nile, the mechanical properties of these metals with the exception of 2024-T4 aluminum, improve as the temperature is reduced. Since annealing of these metals and alloys can affect both the ultimate and yield strengths, care must be exercised under these conditions. 

While the structure/property behavior of numerous shock-recovered metals and alloys has received considerable attention in the literature to date, the response of ceramics, cermets, and other brittle solids (including geological materials) to shock loading remains poorly understood [9], The majority of shock-recovery studies on brittle materials have concentrated on examining... 

L.E. Murr, Effects of Peak Pressure, Pulse Duration, and Repeated Loading on the Residual Structure and Properties of Shock Deformed Metals and Alloys, in Shock Waves and High-Strain-Rate Phenomena in Metals (edited by M.A. Meyers and L.E. Murr), Plenum, New York, 1981, 753 pp. 

The anodes are generally not of pure metals but of alloys. Certain alloying elements serve to give a fine-grained structure, leading to a relatively uniform metal loss from the surface. Others serve to reduce the self-corrosion and raise the current yield. Finally, alloying elements can prevent or reduce the tendency to surface film formation or passivation. Such activating additions are necessary with aluminum. 

Among the alkali metals, Li, Na, K, Rb, and Cs and their alloys have been used as exohedral dopants for Cgo [25, 26], with one electron typically transferred per alkali metal dopant. Although the metal atom diffusion rates appear to be considerably lower, some success has also been achieved with the intercalation of alkaline earth dopants, such as Ca, Sr, and Ba [27, 28, 29], where two electrons per metal atom M are transferred to the Cgo molecules for low concentrations of metal atoms, and less than two electrons per alkaline earth ion for high metal atom concentrations. Since the alkaline earth ions are smaller than the corresponding alkali metals in the same row of the periodic table, the crystal structures formed with alkaline earth doping are often different from those for the alkali metal dopants. Except for the alkali metal and alkaline earth intercalation compounds, few intercalation compounds have been investigated for their physical properties. 

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