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Investment casting is used in the aerospace and power generation industries to produce turbine blades with complex shapes or cooling systems. [14] Blades produced by investment casting can include single-crystal (SX), directionally solidified (DS), or conventional equiaxed blades.
A single-crystal quartz bar grown by the hydrothermal method. In the case of metal single crystals, fabrication techniques also include epitaxy and abnormal grain growth in solids. [10] Epitaxy is used to deposit very thin (micrometer to nanometer scale) layers of the same or different materials on the surface of an existing single crystal. [11]
Directional solidification is the preferred technique for casting high temperature nickel-based superalloys that are used in turbine engines of aircraft. Some microstructural problems such as coarse dendritic structure, long dendrite side branches, and porosity hinder the full potential of single crystal ni-based alloys. [6]
Investment casting leads to a polycrystalline final product, as nucleation and growth of crystal grains occurs at numerous locations throughout the solid matrix. Generally, the polycrystalline product has no preferred grain orientation.
The methods involve heating polycrystalline material above its melting point and slowly cooling it from one end of its container, where a seed crystal is located. A single crystal of the same crystallographic orientation as the seed material is grown on the seed and is progressively formed along the length of the container.
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Aside from alloy improvements, a major breakthrough was the development of directional solidification (DS) and single crystal (SC) production methods. These methods help greatly increase strength against fatigue and creep by aligning grain boundaries in one direction (DS) or by eliminating grain boundaries altogether (SC).
Crystal International Group Limited (HKG:2232) is a company with exceptional fundamental characteristics. Upon building up an investment case for a stock, we should look at various aspects. In the ...