Evilavatar2
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Why in most practical applications, most materials properties are given without specifying crystal directions. Are they trying to say all materials are isotropic?
Material Science -- using materials without specifying crystal directions
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Kevin McHugh
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Evilavatar2 said:
What are you talking about? Many material properties are measure in both the transverse and machine direction. Of course amorphous materials have no crystal structure.
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Evilavatar2 said:
Polycrystalline materials are approximately isotropic when the length scale of interest is much larger than the grain size and the grains are randomly oriented. (Subtlety: materials can have a so-called "texture," which in a materials science context refers not to roughness but to a predominant crystalline orientation, due to processing history.) For example, a handful of iron is going to have a bulk stiffness of 210 GPa, even though the (111) stiffness of each microscopic grain is 270 GPa and the (100) stiffness is 125 GPa. For that matter, the stiffness of low-alloy steels is generally also around 200 GPa because steel is predominantly polycrystalline iron. For certain bulk properties such as stiffness, what you're measuring at the macroscopic scale is essentially the average value of a huge number of randomly oriented microscopic grains.
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berkeman said:
https://www.theengineer.co.uk/issues/june-2015-online/jewel-in-the-crown-rolls-royces-single-crystal-turbine-blade-casting-foundry/
