Reduction of area with the elastic deformation?

[phydis]

In the tensile test practical for ductile materials, up to the elastic limit, the deformation is recoverable (no line defects).

My question is can there be a reduction of area with the elastic deformation?

If yes, how it happens?

I'm a beginner. Thank you!

 

[AlephZero]

In the tensile test practical for ductile materials, up to the elastic limit, the deformation is recoverable (no line defects).

Yes.

My question is can there be a reduction of area with the elastic deformation?

Yes. Look up "Poisson's ratio".

If yes, how it happens?

What sort of answer do you want? Poisson's ratio described what happens, for isotropic materials. For anisotropic materials the concept is similar but there can be up to 21 different parameters rather than just 2 (Young's modulus and Poisson's ratio).

Or do you you want an answer in terms of metallurgy, or basic physics?

 

[phydis]

I can describe what happens in plastic deformation using line defects. And I need a that level explanation for elastic deformation and reduction of area.