| Directional
solidification is a process in which a liquid is converted to a solid by
controlled cooling from one end. In this way a single crystal of a one
component material may be produced.
If
the liquid is at the eutectic composition of a binary alloy, directional
solidification can produce a "composite material" with one of the two solid
phases acting as the matrix and the other as the fiber component of the
composite.
Superalloys
may also be formed into components such as blades for the high temperature
gas turbine using this directional solidification method. By controlling
the cooling rate, grain boundary free blades may be produced. These show
improved creep and corrosion properties as compared to polycrystalline
blades of the same composition. |
