Material Science -- using materials without specifying crystal directions

In summary, the article discusses how polycrystalline materials are approximately isotropic, which is great for certain bulk properties.
  • #1
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?
 
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  • #2
Evilavatar2 said:
Why in most practical applications, most materials properties are given without specifying crystal directions. Are they trying to say all materials are isotropic?
Can you give some examples of the applications you have in mind? Certainly there are applications where crystal axes do matter...
 
  • #3
Evilavatar2 said:
Why in most practical applications, most materials properties are given without specifying crystal directions. Are they trying to say all materials are isotropic?

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.
 
  • #4
Evilavatar2 said:
Why in most practical applications, most materials properties are given without specifying crystal directions. Are they trying to say all materials are isotropic?

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.
 
  • #5
berkeman said:
... Certainly there are applications where crystal axes do matter...

https://www.theengineer.co.uk/issues/june-2015-online/jewel-in-the-crown-rolls-royces-single-crystal-turbine-blade-casting-foundry/
 
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  • #6
Nidum said:
https://www.theengineer.co.uk/issues/june-2015-online/jewel-in-the-crown-rolls-royces-single-crystal-turbine-blade-casting-foundry/
That's truly amazing! Thanks for sharing :smile:
 

FAQ: Material Science -- using materials without specifying crystal directions

1. What is material science?

Material science is a branch of science that deals with the study of the properties, structure, and processing of different materials, such as metals, ceramics, polymers, and composites. It involves understanding how materials behave and how they can be used to create new and improved products.

2. What are some common materials used in material science?

Some common materials used in material science include metals like steel and aluminum, ceramics like glass and clay, polymers like plastics and rubber, and composites like fiberglass and carbon fiber. Researchers also work with newer materials like graphene and nanomaterials.

3. Why is it important to use materials without specifying crystal directions?

Specifying crystal directions can limit the potential applications of a material. By understanding how materials behave without specifying crystal directions, scientists can develop new materials with improved properties that can be used in a wider range of applications.

4. How do scientists study materials without specifying crystal directions?

Scientists use a variety of techniques to study materials without specifying crystal directions, including X-ray diffraction, electron microscopy, and spectroscopy. These methods allow researchers to analyze the structure and properties of materials at the atomic and molecular level.

5. What are some real-world applications of material science?

Material science has many real-world applications, including the development of new and improved materials for use in industries like aerospace, automotive, and energy. It also plays a crucial role in the fields of medicine, biotechnology, and electronics, where materials with specific properties are needed for various applications.

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