Columnar crystal growth

Fig. 7.5. Simulation results of the seeding behaviour and the columnar crystal growth of RGS wafers [36]...

Steps, or growth layers, are structure components for construction of a variety of growth forms in the electrodeposition of metals (e.g., columnar crystals, whiskers, fiber textures). We can distinguish between monoatomic steps, polyatomic microsteps, and polyatomic macrosteps. Only the propagation of polyatomic steps can be observed directly, in situ. 

Figure 4.5 Section through a solidification ingot showing the various solidification zones. The equiaxed zone forms near the mold walls. In the interior is the columnar zone, where crystal growth is in the direction of heat flow. (After Lalena and Cleary, 2005. Copyright John Wiley Sons, Inc. Reproduced with permission.)...

Rapid accumulation of silt and clay on mammillary surfaces stops crystal growth. Large numbers of very small, equant to columnar crystals that grade quickly to a few large columnar crystals (Fig. 6) mark the reinitiation of crystal growth. 

Columnar or dendritic microstructure is found also in most metal and many compound films formed by chemical vapour deposition in certain ranges of condition. As a result of the same mechanism of uninterrupted crystal growth towards the direction of material supply it is further found in films obtained by some deposition techniques from solution, particularly in electroplated films. 

For columnar and needle crystals, growth along the crystal length L is given by... 

Ares, A.E. Gueijman, S.F. Schvezov, C.E. (2010) Experimental Study of the Columnar-to-Equiaxed Transition During Directional Solidification of Zinc-Aluminum Alloys and Composites, /, Crystal Growth, Vol. 312, pp. 2154-2170, ISSN 0022-0248... 

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