Keynote Speakers

Prof. Osman Adiguzel
School of Natural and Applied Sciences, Firat University, Turkey
Title: Thermomechanical Reactions and Thermodynamics of Thermal Memory in Shape Memory Alloys

Speech Title: The STEM university education with active and flipped instruction methodology
Biography: Prof. Osman 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 his studies focused on shape memory alloys. He worked as research assistant, 1975-80, at Dicle University and shifted to Firat University in 1980. He became professor in 1996, and he has been retired due to the age limit of 67; following academic life of 45 years. He published over 60 papers in international and national journals; He joined over 100 conferences and symposia in international and national level as participant, invited speaker or keynote speaker with contributions. He served the program chair or conference chair/co-chair in some of these activities. In particular, he joined in last six years (2014 - 2019) over 60 conferences as Speaker, Keynote Speaker and Conference Co-Chair organized by South Asian Institute of Science and Engineering (SAISE). Dr. Adiguzel served his directorate of Graduate School of Natural and Applied Sciences, Firat University in 1999-2004. He supervised 5 PhD- theses and 3 M.Sc theses. He is also Technical committee member of many conferences. He received a certificate which is being 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: Some materials take place in class of smart materials with adaptive properties and stimulus response to the external changes. Shape memory alloys take place in this group, with the shape recovery and shape memory properties. Shape memory effect is a scientific phenomenon initiated by thermomechanical treatments and performed thermally by heating and cooling after these treatments in bulk level. These alloys are deformed plastically in low temperature condition; strain energy is stored in the material and released on heating by recovering original shape. Shape of these materials is cycled thermally between original and deformed shapes, on heating and cooling, and this behavior is called Thermal Memory or Thermoelasticity. This effect is based on successive crystallographic transformations, thermal and stress induced martensitic transformations, which occurs in crystallographic level on cooling and stressing. Stressing and releasing paths are different at the stress-strain diagram and this result refers to energy dissipation. Thermal induced transformations are exothermic reactions and occur along with lattice twinning on cooling, and ordered parent phase structures turn into twinned martensitic structure. Twinned structures turn into detwinned martensite by means of stress induced martensitic transformation by stressing material. Shape recovery is performed by endothermic austenitic transformation on heating and detwinned martensite structures turn into the ordered parent phase structure.
Thermal induced martensitic transformation occurs with the cooperative movement of atoms in <110 > -type directions on {110}-type planes of austenite matrix by means of lattice invariant shear. Forward martensitic and reverse austenitic transformations are solid state reactions; these reactions do not occur at the equilibrium temperature at Gibbs Free Energy Temperature Diagram and a driving force is necessary for the transformations.
These alloys exhibit another property called superelasticity, which is performed in only mechanical manner. These alloys are deformed in parent phase region, and recover the original shape on releasing the stress, like standard elastic material. Superelasticity is the result of stress-induced martensitic transformation, with which ordered parent phase structures turn into the fully detwinned martensite structures. Superelasticity is performed in non-linear way, unlike normal elastic materials. Loading and unloading paths in both thermoelasticity and superelasticity are different, and hysteresis loop refers to energy dissipation. These alloys are used in building industry, against to the seismic events, due to this property.
Copper based alloys exhibit this property in metastable β-phase region, lattice invariant shears are not uniform in these alloys, and the ordered parent phase structures martensitically undergo long-period complex layered structures.
In the present contribution, x-ray diffraction and transmission electron microscopy studies were carried out on two copper based CuZnAl and CuAlMn alloys. X-ray diffraction profiles and electron diffraction patterns exhibit super lattice reflections inherited from parent phase due to the displacive character of the transformation. X-ray diffractograms taken in a long time interval show that diffraction angles and intensities of diffraction peaks change with the aging time at room temperature. This result reveals a new transformation in diffusive manner.
Keywords: Shape memory effect, martensitic transformations, thermal memory, superelasticity, lattice twinning and detwinning.

Prof. Tao Zhang
College of Resources and Environmental Sciences, China Agricultural University, China

Biography: Prof. Zhang has made outstanding achievements based on the scientific and technology research of the harmless treatment and resources utilization of livestock and poultry waste from theoretical innovation, integrated innovation to collaborative innovation. He deeply studied and developed the theoretical system and technical framework for the recovery of livestock and poultry excrement and phosphorus by pyrolysis-cyclic fluidized-crystal coupling, which has achieved fruitful results in the process of livestock and poultry breeding, such as the coupling of nitrogen and phosphorus, the key regulation and control techniques of heavy metal precipitation separation. He has published 44 academic papers, applied 18 national invention patents (13 have been authorized), applied and been authorized 1 international invention patent and participated 3 publication of monographs.

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