10th International Conference on Physical and Theoretical Chemistry
London, UK
Osman Adiguzel
Firat University, Turkey
Title: Shape memory phenomena and crystallographic basis of reversibility in shape memory alloys
Biography
Biography: Osman Adiguzel
Abstract
Shape memory effect is a peculiar property exhibited a series of alloy system called shape memory alloys, which have dual characteristics called thermoelasticity and superelasticity, from viewpoint of memory behavior. These alloys take place in class of advanced novel materials with these properties and response to the external conditions. Shape memory effect is initiated with thermomechanical processes, on cooling and deformation, and performed on heating and cooling, with which shape of the materials cycles between original and deformed shapes in reversible way. Therefore, this behavior can be called thermoelasticity. This phenomenon is governed by two successive crystallographic transformations, thermal and stress induced martensitic transformations. Thermal induced martensitic transformation occurs along with lattice twinning and ordered parent phase structures turn into multivariant twinned martensite structures in self-accommodating manner, and twinned martensite structures turn into detwinned martensite by means of stress induced martensitic transformation on stressing.
Thermal induced martensitic transformation occurs on cooling, with cooperative movement of atoms in <110 > -type directions on the {110} - type planes of austenite matrix, along with lattice twinning and ordered parent phase structures turn into twinned martensite structures. The twinned structures turn into detwinned structures by means of stress induced transformation by stressing the material in the martensitic condition. Martensitic transformations are diffusionless transformations, and movements of atoms are confined into neighbor atom distances.