Effect of the Conditions of Crystallization of Rapidly Quenched TiNiCu Amorphous Alloys with High Copper Contents on the Characteristics of Martensite Transformations and Shape Memory Effect
“…This allowed attaining noticeable SME in these alloys. The experimental data of this work are in a good agreement with earlier results for the TiNi-TiCu system alloys with a high copper content produced by the melt spinning technique (Chang, Wu, and Kimura 2007;Morgiel et al 2002;Shelyakov, Matveeva, and Larin 1999;Shelyakov et al 2019;Sitnikov et al 2018).…”
Section: Discussionsupporting
confidence: 91%
“…Amorphization of the alloys is achieved at high copper contents (above 20 at.%) by means of rapid cooling at rates of about 10 6 K/s (Kang et al 2010;Shelyakov et al 2011;Senkovskiy et al 2012) which can be implemented using the currently most widely applied amorphous metallic alloy technology of melt spinning onto the outer surface of a rapidly rotating wheel (Morgiel et al 2002;Shelyakov et al 2011;Pushin et al 1997;Shelyakov, Matveeva, and Larin 1999). It has been recently shown that an increase in the copper content in melt-spun alloys to 38 at.% has a considerable effect on their structural properties and performance (Sitnikov et al 2017;Shelyakov et al 2019;Sitnikov et al 2018). It should be noted that the melt spinning technique is suitable for the fabrication of up to 4 mm wide ribbons.…”
Rapidly quenched quasibinary TiNi–TiCu system alloys with high copper contents (above 20 at.%) exhibit excellent shape memory effect and have considerably narrower hysteresis as compared with the TiNi binary alloy, this advantage being of special importance for cyclic load applications, e.g. for microelectromechanics (MEMS). The aim of this work is to study the effect of annealing parameters and copper content on the shape memory effect in TiNiCu alloys. Thin amorphous ribbons of TiNi-TiCu alloys with copper contents of 25 to 40 at.% were produced by planar flow casting at a melt cooling rate of about 106 K/s. The alloys were crystallized by isothermal annealing with variable duration and by exposing specimens to a short (10 ms) electric pulse. Increasing the copper content to above 30 at.% considerably reduces the plasticity and shape memory effect of the alloys. However, significant reduction of annealing duration greatly improves the shape memory performance due to prevention of the formation of brittle Ti-Cu phases in the alloys structure.
“…This allowed attaining noticeable SME in these alloys. The experimental data of this work are in a good agreement with earlier results for the TiNi-TiCu system alloys with a high copper content produced by the melt spinning technique (Chang, Wu, and Kimura 2007;Morgiel et al 2002;Shelyakov, Matveeva, and Larin 1999;Shelyakov et al 2019;Sitnikov et al 2018).…”
Section: Discussionsupporting
confidence: 91%
“…Amorphization of the alloys is achieved at high copper contents (above 20 at.%) by means of rapid cooling at rates of about 10 6 K/s (Kang et al 2010;Shelyakov et al 2011;Senkovskiy et al 2012) which can be implemented using the currently most widely applied amorphous metallic alloy technology of melt spinning onto the outer surface of a rapidly rotating wheel (Morgiel et al 2002;Shelyakov et al 2011;Pushin et al 1997;Shelyakov, Matveeva, and Larin 1999). It has been recently shown that an increase in the copper content in melt-spun alloys to 38 at.% has a considerable effect on their structural properties and performance (Sitnikov et al 2017;Shelyakov et al 2019;Sitnikov et al 2018). It should be noted that the melt spinning technique is suitable for the fabrication of up to 4 mm wide ribbons.…”
Rapidly quenched quasibinary TiNi–TiCu system alloys with high copper contents (above 20 at.%) exhibit excellent shape memory effect and have considerably narrower hysteresis as compared with the TiNi binary alloy, this advantage being of special importance for cyclic load applications, e.g. for microelectromechanics (MEMS). The aim of this work is to study the effect of annealing parameters and copper content on the shape memory effect in TiNiCu alloys. Thin amorphous ribbons of TiNi-TiCu alloys with copper contents of 25 to 40 at.% were produced by planar flow casting at a melt cooling rate of about 106 K/s. The alloys were crystallized by isothermal annealing with variable duration and by exposing specimens to a short (10 ms) electric pulse. Increasing the copper content to above 30 at.% considerably reduces the plasticity and shape memory effect of the alloys. However, significant reduction of annealing duration greatly improves the shape memory performance due to prevention of the formation of brittle Ti-Cu phases in the alloys structure.
“…В настоящей работе объектом исследования являлись сплавы квазибинарной системы TiNi−TiCu с содержанием титана 50 at.% и содержанием меди 30 at.%, которые были изготовлены методом сверхбыстрой закалки из расплава [10][11][12][13][14]. Предварительно слитки сплавов необходимой композиции были приготовлены из сверхчистых металлов (электродный никель Н0, бескислородная медь М0, йодидный титан H 1 min ) с шестикратной переплавкой в дуговой печи в атмосфере аргона для обеспечения однородности.…”
Section: материалы и методы исследованияunclassified
“…В области близкой к средней части, полученного после КВД диска (левая часть шлифа), присутствуют преимущественно области с мартенситной структурой В19 и средним размером зерна 0.5−0.7 µm (рис. 5, b, е), типичные для этих сплавов после изотермической кристаллизации [11]. В средней части шлифа в приповерхностных областях, сформированных вследствие сдвиго-…”
Section: конференция "unclassified
“…Однако данные сплавы с высоким содержанием меди (более 20 ат.%) при получении стандартными методами в кристаллическом состоянии являются хрупкими, так как в них образуются фазы Ti−Cu, которые охрупчивают весь материал и препятствуют протеканию в них мартенситных превращений, ответственных за проявление эффектов памяти формы [10]. Одним из перспективных способов получения " работоспособных" сплавов с эффектом памяти формы на основе квазибинарной системы TiNi−TiCu -сверхбыстрая закалка из жидкого состояния [11]. Данный метод экстремального воздействия позволяет получать тонкие ленты в кристаллическом, аморфно-кристаллическом и аморфном состоянии.…”
There is a splitting of crystallization peaks in the region of lower temperatures, that is, regions are formed in which low-temperature crystallization is possible. It was found that HPC causes a decrease in the thermal effect of crystallization upon heating alloys with a high copper content relative to the initial amorphous state obtained after quenching from the melt. After DSC crystallization in the alloy, a structure was formed that is characterized by inhomogeneity in the cross section of the sample with stratification according to the size of the structural elements. In the regions of partial nanocrystallization of the amorphous state after crystallization, a finer-grained structure was formed than in the main bulk of the sample. The obtained results convincingly demonstrate the influence of HPC on the formation of a crystalline structure from amorphous Ti50Ni20Cu30 alloys.
This work is devoted to the study of the influence of electric pulse heat treatment of rapid-quenched Ti50Ni25Cu25 alloy ribbons (at. %) with a surface crystal layer. The object of the study was a rapid-quenched layered amorphous-crystal ribbon with a thickness of about 30 µm and a width of about 1.5 mm, in which a thin surface crystal layer (2.5 µm) was present on the non-contact side relative to the quenching wheel. The alloy samples were subjected to electric pulse treatment by passing a single pulse of electric current through the sample with a variable duration. For comparison, samples of the alloy were obtained, crystallized by standard isothermal heat treatment. The samples were characterized by means of scanning electron microscopy techniques, energy dispersive X-ray analysis and differential scanning calorimetry. It was shown that electric pulse treatment with an exposure time of less than 1 second leads to a significant change in the formed crystalline structure in comparison with the structure obtained by isothermal treatment. The microstructure of such samples in cross section is characterized by an uneven distribution of crystals over the thickness of the ribbon: columnar crystals are observed from the contact and non-contact sides of the ribbon, and large crystals are present in the inner part of the ribbon.
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