Journal of Petroleum & Environmental Biotechnology

Temperature deformation relation in memory behavior of shape memory alloys

2^nd International Conference on Petrochemistry and Chemical Engineering

March 06, 2023 | Webinar

Osman Adiguzel

Firat University, Turkey

Keynote: J Pet Environ Biotechnol

Abstract:

Shape memory effect is a temperature dependent phenomenon exhibited by certain alloy systems called shape memory alloys. These alloys take place in the class of smart and advanced structural materials, with the response to the variation of temperature and external conditions. This behavior is initiated on cooling and plastically deformation and performed on heating and cooling, with which shape of the material cycles between original and deformed shapes in reversible way. Therefore, this behavior is called thermoelasticity. The origin of this phenomenon lies in the fact that the material changes its internal crystalline structure with changing temperature Thermoelasticity is governed by thermal and stress induced martensitic transformations Thermal induced martensite occurs along with lattice twinning and ordered parent phase structures turn into twinned martensite structures by means of lattice invariant shears, and these structures turn into detwinned martensitic structures by means of stres induced transformation. Lattice Twinning occurs in <110 > -type directions on the {110}-type plane of austenite matrix, by means of lattice invariant shear. These alloys exhibit another property, called superelasticity, which is performed mechanically stressing in elasticity limit at a constant temperature in parent phase region, and shape recovery occurs instantly upon releasing. Superelasticity is governed by stress induced transformation, and ordered parent phase structure turns into the fully detwinned martensite structure with stressing. Stressing and releasing paths are different at stress-strain diagram, and hysteresis loops refers to the energy dissipation. The crystal structure cycles between the parent phase structure and detwinned martensite structures on stressing and releasing. The twinning occurs with internal stresses, while detwinning occurs with the external stresses. Shape memory effect is performed in a temperature interval after first cooling and stressing processe, whereas superelasticity is performed mechanically in a constant temperature in parent phase region, just over the austenite finish temperature. Deformation at different temperature exhibits different behavior beyond shape memory effect and superelasticity. Copper based alloys exhibit this property in metastable beta-phase region, which has bcc based structures at high temperature parent phase field. Lattice invariant shear and twinning is not uniform in these alloys and cause to the formation of complex layered structures, depending on the stacking sequences on the close-packed planes of the ordered lattice. In the present contribution; x-ray and electron diffraction studies were carried out on two solution treated copper based CuZnAl and CuAlMn alloys. Electron and x-ray diffraction exhibit super lattice reflections. Specimens of these alloys were aged at room temperature, and a series of x-ray diffractions were taken at different stages of aging in a long-term interval. X-Ray diffraction profiles taken from the aged specimens in martensitic conditions reveal that crystal structures of alloys chance in diffusive manner, and this result refers to the stabilization.
Recent Publications:
1. Adiguzel O (2018) Thermoelasticity, Superelasticity and Nanoscale Aspects of Structural Transformations in Shape Memory Alloys. In: Struble L., Tebaldi G. (eds) Materials for Sustainable Infrastructure, GeoMEast 2017.Sustainable Civil Infrastructures. Springer
2. Adiguzel O (2015) Phase Transitions and Elementary Processes in Shape Memory Alloys, Advanced Materials Research 1101 124-128, Trans Tech Publications, Switzerland
3. Adiguzel O (2015) Nanoscale Aspects of Phase Transitions in Copper Based Shape Memory Alloys, Nanotechnology in the Security Systems, NATO Science for Peace and Security Series C: Environmental Security 131-134
4. Adiguzel O (2014) Self-accommodating Nature of Martensite Formation in Shape Memory Alloys, Solid State Phenomena 213 114-118, Trans Tech Publications, Switzerland
5. Adiguzel O (2013) Phase Transitions and Microstructural Processes in Shape Memory Alloys, Materials Science Forum 762 483-486, Trans Tech Publications, Switzerland

Biography :

Osman 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 on shape memory alloys. He worked as research assistant, 1975-80, at Dicle University and shifted to Firat University, Elazig, Turkey in 1980. He became professor in 1996, and he has already been working as professor. He published over 80 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 of oral or poster. He served the program chair or conference chair/co-chair in some of these activities. In particular, he joined in last seven years (2014 - 2020) over 70 conferences as Keynote Speaker and Conference Co-Chair organized by different companies. He supervised 5 PhD- theses and 3 M.Sc.- theses. He 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.