Diffraction

[immortal]

Do all materials diffract. What is the principle behind x-ray diffractionn?:D

[Robert]

For x-ray diffraction you need a material that is crystalline. For residual stress measurement this is typically a metal or a ceramic.

Diffraction is caused by the scattering of the x-ray beam by the material. Since the material is crystalline, it has a regular spacing of atoms. This regular spacing of the atoms causes the scattered x-rays to interfere with each other constructively at some positions in space. These constructive regions are the diffraction peaks. Where there is no diffraction peak, the x-rays are destructively interfering.

[RadMan]

It is also improtant to know that the intensity of the diffraction peak is dependent on the number of randomly oriented grains that are available to diffract from. If the grains of the material are all laying in the same direction (prefered orientation) then you may not see a peak at the expected 2theta angle. The same thing can happen if the grains are too large (the sample volume becomes smaller). In general, as long as the crystalline material satisfies "Bragg's Law" (λ=2d SinΘ) then you will see a diffraction peak at some 2theta angle.

[arp856]

Hello
I am M S student and i am working on my final project
I have a question
I am trying to measure residual stress in extrudate AA2024
What kind of measurement technic you refer to me?
tanks for your attention
sincerely
arp 856

[yukuigao]

You can have a try by XRD and neutron.

[Emma6Ward]

Principle of X-ray diffraction.... a wealth of structural, physical and chemical information about the material investigated can be obtained....

[DarrylFerguson]

It is the apparent bending of waves around small obstacles and the spreading out of waves past small openings.