Scientific Committee
Title:
Shape memory phenomena and deformation temperature dependent for reversibility in shape memory alloysBiography
Dr. Adiguzel graduated from Department of Physics, Ankara University, Turkey in 1974 and received PhD- degree from Dicle University, Diyarbakir-Turkey. He studied at Surrey University, Guildford, UK, as a post-doctoral research scientist in 1986-1987, and studied were focused on shape memory effect in shape memory alloys. His academic life started following graduation by attending an assistant to Dicle University in January 1975. He became professor in 1996 at Firat University in Turkey, and retired on November 28, 2019, due to the age limit of 67, following academic life of 45 years. He supervised 5 PhD- theses and 3 M. Sc- theses and published over 80 papers in international and national journals; He joined over 120 conferences and symposia in international level with contribution. He served the program chair or conference chair/co-chair in some of these activities. Also, he joined in last six years (2014 - 2019) over 60 conferences as Keynote Speaker and Conference Co-Chair organized by different companies. Additionally, he joined over 230 online conferences in the same way in pandemic period of 2020-2024. He received a certificate awarded to him and his experimental group in recognition of significant contribution of 2 patterns to the Powder Diffraction File – Release 2000. The ICDD (International Centre for Diffraction Data).
Research interests
Shape memory effect and crystallographic transformations in shape memory alloys and other alloys. Electron microscopy and X-Ray Crystallography. Alloy modeling and simulation.
Abstract
Shape memory alloys take place in a class of advanced smart materials by exhibiting dual memory characteristics, Shape Memory Effect and Superelasticity. Shape Memory Effect is initiated with thermomechanical processes on cooling and deformation and performed thermally 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 crystallographic transformations, thermal, and stress induced martensitic transformations. Thermal induced martensitic transformation occurs on cooling with the cooperative movement of atoms in <110 > -type directions on {110}-type close packed planes of austenite matrix along with the lattice twinning and ordered parent phase structures turn into twinned martensitic structure. Twinned structures turn into detwinned martensite by means of stress induced martensitic transformation with deformation in the low temperature condition. Lattice twinning and detwinning reactions play important role in martensitic transformations, and they are driven by the internal and external forces, by means of inhomogeneous lattice invariant shears. Superelasticity is performed with mechanically stressing and releasing the material in elasticity limit at a constant temperature in the parent phase region, and material recovers the original shape upon releasing, by exhibiting elastic material behavior. Superelasticity is also result of stress induced martensitic transformation, and the ordered parent phase structures turn into the detwinned martensite structures by stressing in parent phase region. It is important that these alloys are deformed in the low temperature condition for Thermoelasticity, and they are stressed in the parent phase region for Superelasticity. Deformation at different temperature exhibits different characteristics beyond Thermoelasticity and Superelasticity. Copper based alloys exhibit this property in metastable β-phase fields. Lattice twinning and lattice invariant shear is not uniform in these alloys and cause to the formation of complex layered structures.
In the present contribution, x-ray and electron diffraction studies were carried out on two copper- based CuAlMn and CuZnAl alloys. X-ray diffraction profiles and electron diffraction patterns exhibit super lattice reflections. X-ray diffractograms taken in a long-time interval show that diffraction angles and intensities of diffraction peaks change with the aging duration at room temperature. This result refers to the rearrangement of atoms in diffusive manner.
What the audience take away from presentation:
Shape memory alloys are multifunctional materials and shape memory effect is multidisciplinary subject. Also, every scientist is not familiar with every subject of the science. Therefore, I will introduce the basic terms and definitions related the topics of my Talk at the beginning, and I will introduce the experimental result on the specimens.
