2023 3rd International Conference on Advanced Materials and Chemical Engineering(AMCE2023)
Keynote Speakers
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Prof. Dr. Osman Adiguzel

Firat University, Elazig, Turkey

Speech titleThe Role of Thermal and Mechanical Treatments in Reversibility Behavior of Shape Memory Alloys









Abstract

Shape memory effect is a peculiar property exhibited by certain alloy system in the β-phase fields, with chemical compositions, which is characterized by the recoverability of two certain shapes of material at different temperatures.  These alloys possess two unique abilities: the capacity to recover large strains and to generate internal forces during their activation. This phenomenon is initiated with thermal and mechanical treatments on cooling and deformation, and performed thermally on heating and cooling, with which shape of material cycles between original and deformed shapes in reversible way. Therefore, this behavior can be called Thermoelasticity.

The basis of this phenomenon is result of the stimulus-induced structural phase transformations, thermal and stress induced martensitic transformations, which govern the remarkable changes in internal crystalline structure and properties of the materials. 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 with deformation. Martensitic transformations are diffusionless transformations, and movements of   atoms are confined into the neighbour atom distances. This is plastic deformation, due to the soft character of these alloy in low temperature condition. Strain energy is stored in the material with deformation and released upon heating, by recovering the original shape.



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Prof. Ying Yu

Central China Normal University

Speech title
Abstract