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1

I am not sure thermal expansion is much greater in polycrystals than in single crystals (http://nvlpubs.nist.gov/nistpubs/jres/14/Jresv14n5p523_A1b.pdf, Fig. 13). Wikipedia article that you quote says that single crystals have higher creep strength at high temperatures, so they can provide higher turbine efficiency.


3

Single crystal jet turbine blades are grown in a substantially different way than most crystals. The following article gives details of some of the R&D and large scale production process that is used. http://www.tms.org/superalloys/10.7449/1980/superalloys_1980_205_214.pdf


4

Okay so admittedly I know nothing about jet turbines, however I know a little something about crystals. The occupied lattice points of a single crystal are interacting with good overlap of atomic orbitals. If you have a d-block metal then you get the standard d-d and d-p interactions as predicted by tight binding and Hubbard models. Grain boundaries are ...


1

Engineers usually treat thermal expansion as isotropic, which means the expansion occurs with the same magnitude in every direction. This means that an unconstrained object will have a constant strain and zero stress associated with thermal expansion, it's as if object just scaled up. However, as you suspected, materials with an organized structure can be ...


3

Careful! The essence of your question is a good thought but I think you are having several misconceptions. First of all, it doesn't make sense to talk about a phonon being directed towards a single atom. Phonons are delocalized. Secondly, the "input of temperature required to eject an electron" is a dangerous idea. You need to input energy to eject an ...



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