Modeling and interpretation of tweed microstructures in face-centered-cubic solids

Abstract

Using molecular-dynamics simulations and an interatomic potential that had been designed to be unstable to 〈110〉{11¯0} shears, we studied the mechanisms of tweed formation in face-centered-cubic (fcc) crystals. We found that tweed is most probably a premartensitic phenomenon that nucleates homogeneously in strongly anharmonic solids. Yet tetragonal strain fields will enhance the formation of tweed in the crystal. Unlike the case of body-centered-cubic (bcc) crystals, we did not find any particular feature in the interatomic potential that is common to all materials showing a tweed instability. Finally, we showed that solitons with hyperbolic-tangent strain fields are the kind of elastic shear waves that propagate in such anharmonic solids.