Directional grain growth

Figure 10.32 Directional grain growth during liquid-phase sintering of single-crystal W spheres with nickel at 1640°C, showing (a) the microstructure and (b) the microprobe analysis. (From Ref. 55.)...

The matte can be treated in different ways, depending on the copper content and on the desired product. In some cases, the copper content of the Bessemer matte is low enough to allow the material to be cast directly into sulfide anodes for electrolytic refining. Usually it is necessary first to separate the nickel and copper sulfides. The copper—nickel matte is cooled slowly for ca 4 d to faciUtate grain growth of mineral crystals of copper sulfide, nickel—sulfide, and a nickel—copper alloy. This matte is pulverized, the nickel and copper sulfides isolated by flotation, and the alloy extracted magnetically and refined electrolyticaHy. The nickel sulfide is cast into anodes for electrolysis or, more commonly, is roasted to nickel oxide and further reduced to metal for refining by electrolysis or by the carbonyl method. Alternatively, the nickel sulfide may be roasted to provide a nickel oxide sinter that is suitable for direct use by the steel industry. 

CVD graphite can have several structural forms columnar, laminar, or isotropic. The columnar form is shown in Fig. 7.2. The crystallites are deposited with the basal planes (ab directions) essentially parallel to the deposition surface. Their structure tends to be columnar (cone-like) as a result of uninterrupted grain growth toward the reactant source. 

Here, however, unlike binaries or multinaries, the emf is inherently unstable273 274 as the same processes allowing for an excess emf to be measured are also allowing for sintering and grain growth (electrochemical Ostwald ripening275 273). In addition, there has to be paid attention to the fact that the emf refers to the excess chemical potential of silver directly at the electrode/electrolyte interface.273... 

During discontinuous grain growth, the grain boundaiy can move as is shown in Figure 16.14 [37]. Here we see that the grain boundary velocity is perpendicular to the grain boundary and in the direction... 

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