>> The polycrystalline and monocrystalline alloys:

At a micro-structural level, the behaviour depends on the crystallographic nature of the sample.
If it is a :

· Monocrystal : the alloy is made up of only one crystal (picture 1)
· Polycrystal : the alloy is made up of several crystals (picture 2)

Picture 1: Monocrystalline alloy

Picture 2: Polycrystalline alloy

A monocrystalline alloy will have better performances than polycrystalline alloy (picture 3), This one will be able for example to have a more significant recoverable deformation (10% against 3%).

Picture 3: Comparison of reversible deformations