Crystal whiskers


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Crystal whiskers

Single crystals that have grown in filamentary form. Some grow from their base: either these are extruded to relieve pressure in the base material or they grow as a result of a chemical reaction at the base. In both cases, the growth occurs at a singularity in the base material. Other crystal whiskers grow at their tip, into a supersaturated medium, and the filamentary growth results from a strong anisotropy in the growth rate. See Single crystal

Great interest in whiskers developed after it was discovered that the strength exhibited by some whiskers approached that expected theoretically for perfect crystals. This great strength results from the internal and surface perfection of the whiskers, whereas the strength of most materials is limited by defects. The interest in the high strength of the whiskers centered on the possibility of using them in composites to increase the strength of more ductile matrix materials. Fibers of silica, boron, and carbon, which are much easier to fabricate in large quantity than whiskers, exhibit similarly high strengths, and are now used in composites. See Crystal defects