Crystal copper-based alloys

Metals which owe their good corrosion resistance to the presence of thin, passive or protective surface films may be susceptible to pitting attack when the surface film breaks down locally and does not reform. Thus stainless steels, mild steels, aluminium alloys, and nickel and copper-base alloys (as well as many other less common alloys) may all be susceptible to pitting attack under certain environmental conditions, and pitting corrosion provides an excellent example of the way in which crystal defects of various kinds can affect the integrity of surface films and hence corrosion behaviour. 

Pure bulk iron in the fee crystal structure (7-Fe) only exists at very high temperatures (between 1183 and 1667K). However, 7-Fe may be stabilized at low temperatures as small coherent precipitates in copper or copper-alloy matrices or as thin epitaxial films on a Cu or Cu-based alloy substrate [113], (114). Recently the interest in 7-Fe has been revived due to the existence of multiple magnetic states revealed by band-structure calculations [115], which is believed to be related to INVAR phenomena in 7-Fe-based alloys [116]. 

Because of its high thermal conductivity, diamond is an excellent heatsink material, mostly for hIgh-density electronic circuits. Athin slice, in size up to 3 X 3 X1 mm, is cut from a natural crystal, metallized by sputtering a gold alloy and soldered to a copper base. A typical diamond heat-sink configuration is shown in Fig. 12.12. ... 

Christophe J, Doneux T, Buess-Herman C (2012) Electroreduction of carbon dioxide on copper-based electrodes activity of copper single crystals and copper-alloys. Electrocatalysis 3 139-146... 

Lately, however, some surprising exceptions have been found to the general rule of low plasticity in ceramics. One is the perovskite oxide strontium titanate, SrTiOs. Recent studies on single crystals have revealed a transition from nonductile to ductile behavior in this material not only at temperatures above 1000°C, but again, below 600°C. Even more unexpectedly, it reached strains of 7 percent at room temperature with flow stresses comparable to those of copper and aluminum alloys. At both the high and low temperatures, the plasticity appears to be owing to a dislocation-based mechanism (Gumbsch et al., 2001). 

In conclusion, we note that deposition of submono- and monolayers of adatoms is the most controllable and reliably predictable method of obtaining metallic nanodimension compositions. At least two or three kinds of adatoms can be deposited in a strictly layer-by-layer fashion on single-crystal substrates [217], and mixed adlayers can also be obtained. The combined deposition of adatoms and phase deposits of metals [217] is even more promising. Among the metals, HTSC components such as lead, thallium, bismuth, and copper rank among the most thoroughly studied adatomic systems. Electrodeposition methods are also applied to the technological preparation of conventional superconductors based on Nb-Sn alloys [218]. 

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