Solidification, directional eutectic

For an alloy droplet, the post-recalescence solidification involves segregated solidification and eutectic solidification. 619 Droplet cooling in the region (1),(2) and (6) can be calculated directly with the above-described heat transfer model. The nucleation temperature (the achievable undercooling) and the solid fraction evolution during recalescence and post-recalescence solidification need to be determined additionally on the basis of the rapid solidification kinetics. 154 156 ... 

Fig. 4 Schematic representation of control over block copolymer thin film orientation by directional eutectic solidification. The scheme shows control of polystyrene-b-polyethylene (PS-b-PE) block copolymer microdomain orientation through directional crystallization of benzoic acid (BA), (taken from [95])...

Rosa CD, Park C, Thomas EL, Lotz B. 2003. Microdomain patterns from directional eutectic solidification and epitaxy. Nature 405 433 437. 

The orientation of the lamella tends to be along the direction of heat flow. In polycrystalline grains solidified from a melt of eutectic composition, the orientation is more or less random but the spacing of the lamella is indicative of the rate the material was solidified. However, if a eutectic composition is directionally solidified, the lamella will be aligned along the solidification direction to form what is known as an in situ composite. If the eutectic system happens to be a low volume fraction eutectic (the eutectic composition is such that A B or vice versa), the minority phase will form a rod-like structure rather than the lamella structure described above. The spacing of the rods will still be governed by the... 

A major method of controlling solidification porosity is directional solidification. Such solidification of eutectics results in unidirectional leunellar or rod "reinforced" composites, wherein the thickness of the lamellae or rod diameters are inversely proportional to the solidification... 

An important example of an MMC in situ composite is one made by directional solidification of a eutectic alloy. The strength, (, of such an in situ metal-matrix composite is given by a relationship similar to the HaH-Petch relationship used for grain boundary strengthening of metals ... 

More recent extensions of the theory (see citations in [122]) gave indications that the orientation of the lamellae (under isotropic material parameters) is not necessarily parallel to the growth direction of the front but may be tilted so that the lamellae travel sideways at some specific angles [138]. Finally it was found that the standard model of eutectic solidification has an intrinsic scaling structure [141-147]... 

Coaxial intergrowth is a paragenetic relation that describes crystals of two different species growing with a common axis the misfit ratios between the two crystals in the direction of the common axis are small, without exception. The formation of coaxial intergrowth can be understood to be one crystal conjunct to the other in an epitaxial relation, where both continue to grow. If a liquid of eutectic A-B component is solidified from one side (unidirectional solidification), crystals of the two phases A and B precipitate in dotted, columnar or lamellar (with common axis) form, and show unique textures for unidirectional solidification. This is a well known phenomenon in metallurgy. 

It has been established that the structure of the shaped Al203-Zr02(Y203) eutectic composite, as well as the structure of composites obtained by other methods of directional solidification in this system, consists of two phases the matrix, which is alumina, and stabilized zirconia [47]. In this Al203-Zr02 systan, alumina is the... 

Figure 11-15 shows eutectic solder bumps placed onto a 18 x 18 test substrate with 100-pm diameter pads on 250 pm centers. The solder volume deposited per pad is equivalent to a drop diameter of 100 pm. The solder bumps acquire the shape shown in Figure 11-15 is a result of rapid solidification [18]. The bumps were placed at the rate of 400 s by raster-ing the substrate in the horizontal direction of the rows of solder bumps. 

The Inorganic discussed in Chapter 7. Eutectic or directed solidification also makes use of heat hh a diffusion limitation to make a composite of anisotropic stacked layers from an eutectic melt, as described in Chapter 8. 

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