Reconstructive and Displacive Transformations: Part IV
Channel: bhadeshia123
Date: 04/11/2011

Part 4 in the story of displacive and reconstructive phase changes.

Displacive transformations involve the coordinated
movement of atoms. Such movements cannot be
sustained against strong defects such as grain boundaries. This is why martensite or bainite plates are unable to cross
grain boundaries. Less drastic defects such as isolated
dislocations also hinder the progress of such transformations, but can often be incorporated into the
martensite lattice. 

It is well established that
when the strain in the austenite becomes sufﬁciently
large, the motion of glissile interfaces becomes impossible, causing the transformation to halt.
This applies to all cases involving the translation of
glissile interfaces, whether their motion leads to a phase
change, or simply to a reorientation of the lattice as
in mechanical twinning. The phenomenon is known as
mechanical stabilisation and is a sure way of distinguishing the displacive and reconstructive mechanisms of
solid state transformations.
 
More details on 
http://www.phase-trans.msm.cam.ac.uk/2006/stabilisation.html