The mechanism of plasticity in non-polymeric glasses

In the sections that follow, we consider the kinematics and kinetics of plastic flow by repeated nucleation of STs, primarily in metallic glasses and amorphous silicon as key examples. Similar corresponding applications to glassy polymers are covered in Chapter 8. 

The kinematics of piasticity in giassy soiids by shear transformations 

In the broadest sense all inelastic deformation in glassy solids can be viewed as arising from a time series of STs occurring in small volume elements of atom clusters, under the action of an applied shear stress and emanating from certain 

Since shear deformation has a habit of undergoing localization in the form of shear bands by interaction of STs, the size of the RVE at times becomes difficult to establish and can become quite large. We consider shear localization in Section 7.8, but concentrate here first on the quasi-homogeneous process of flow by relatively non-interacting additions of STs under stress. 

At the outset we note that plasticity achieved by STs is always nucleation-controlled and, with few exceptions, once formed, individual STs don t broaden by translation of their interfaces. We call such transformations sessile. 

---