Scientific Committee

Biography

Dr. Adiguzel graduated from Department of Physics, Ankara University, Turkey in 1974 and received PhD- degree from Dicle University, Diyarbakir-Turkey. He has 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 180 online conferences in the same way in pandemic period of 2020-2023.
Dr. Adiguzel served his directorate of Graduate School of Natural and Applied Sciences, Firat University, in 1999-2004. 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) also appreciates cooperation of his group and interest in Powder Diffraction File.

Abstract

Metals and alloy systems have different phases at different temperatures and these phases are described in phase diagrams depending on the alloy composition. Shape memory effect is a peculiar property exhibited by shape memory alloys at the β-phase region with chemical compositions. These alloys are very sensitive to external conditions, and phase structures turn into other crystal structures with the variation of temperature and stressing, by means of phase transitions or phase transformations. Lattice vibrations (phonons), atomic bonds, interatomic interactions, and other factors play an important role in the processing of these events. Shape memory effect is initiated with thermomechanical processes on cooling and deformation and performed thermally on heating and cooling, with which shape of materials cycles between original and deformed shapes in reversible way. This behaviour is governed by crystallographic transformations, thermal, and stress induced martensitic transformations. Thermal induced martensitic transformation occurs on cooling with cooperative movements of atoms in <110 > -type directions on the {110} - type planes of austenite matrix, along with lattice twinning reaction, and ordered parent phase structures turn into twinned martensite structures.  The twinned structures turn into detwinned martensite structures by means of stress induced transformation by stressing the material in the martensitic condition. Lattice twinning and detwinning reactions play important role in martensitic transformations, and they are driven by inhomogeneous lattice invariant shears. 
These alloys exhibit another property called superelasticity, which is performed in only mechanical manner with stressing material in elasticity limit at a constant temperature in parent phase region, and the material recovers the original shape on releasing the external stress, by exhibiting elastic material behaviour. Superelasticity is also result of stress induced martensitic transformation and ordered parent phase of the alloy turns into the detwinned martensitic structure with stressing. Although superelasticity exhibits elastic material behaviour, stressing and releasing paths are different at stress-strain diagram. Also, stress-strain profile is nonlinear, and hysteresis loop refers to the energy dissipation. 
Copper based alloys exhibit this property in metastable β-phase region. Lattice invariant shear and twinning is not uniform in these alloys, and gives rise to the formation of layered structures, like 3R, 9R or 18R depending on the stacking sequences on the close-packed planes of the ordered lattice. 
In the present contribution, x-ray diffraction and transmission electron microscopy (TEM) studies were carried out on copper based CuZnAl and CuAlMn alloys.  X-ray diffractograms and electron diffraction patterns exhibit super lattice reflection. X-ray diffractograms taken in a long-time interval show that locations and intensities of diffraction peaks change with the aging time at room temperature, and this result refers to the rearrangement of atoms in diffusive manner.