Ercan ERCAN, Fethi DAĞDELEN, Mediha KÖK, Esra BALCI

Şekil Hatırlamalı Ni30Ti50Cu20 Alaşımının Termodinamik Özelliklerinin İncelenmesi

Şekil hatırlamalı NiTiCu alaşımı ark-ergitme yöntemi ile üretildi ve faz dönüşüm sıcaklıkları, bazı termodinamik parametreleri ile mikroyapısal özellikleri araştırıldı. 10°C/dak. ısıtma-soğutma hızı ile alınan DSC sonuçlarına göre; austenite başlangıç sıcaklığı (As) 23.5 oC, austenite bitiş sıcaklığı (Af) 50.6 oC, martensit başlangıç sıcaklığı (Ms) 26.7 oC ve (Mf) -0.10 oC olarak bulundu. Farklı ısıtma hızlarında alınan DSC ölçümlerine göre ise alaşımın martensit fazdan austenite faza geçerken dönüşüm sıcaklıkları (As ve Af) değişirken, austenite fazdan martensit faza geçerken dönüşüm sıcaklıklarının (Ms ve Mf) değişmediği görülmüştür. Kissinger metodu ile bulunan aktivasyon enerjisi Ea=63.208 kJ/mol olarak bulunmuştur. Gibbs serbest enerjisi ısıtma-soğutma hızlarıyla küçük değişimler göstermiştir. DSC eğrilerinden tek-adımlı B2 ↔B19 faz geçişi görülmüş ve bu fazların kristal yapıları XRD analizi ile belirlenmiştir. Bununla birlikte Ti2(Ni, Cu) çökeltilerinin yanı sıra NiTi alaşımının interfazlarında çözünen Cu elementlerinin TiNi0,8Cu0,2 formundaki matrislerine rastlanmıştır. SEM-EDX sonuçları ile alaşımdaki Ti2(Ni, Cu) çökeltilerinin atomik yüzdeleri belirlenmiştir. Alaşımın mikrosertliği 219 HV olarak bulunmuştur. Bu değer, artan Cu miktarının geleneksel ikili NiTi alaşımlarını daha yumuşak materyal haline getirdiğini göstermiştir.

Investigation of Thermodynamic Properties of Ni30Ti50Cu20 Shape Memory Alloy

In this study, after producing Ni30Ti50Cu20 shape memory alloy by using arc melting technique, some examinationwas performed, including phase transformation temperatures, microstructural features, and certain thermodynamicparameters. The DSC thermogram run with 10°C/min heating-cooling rate, and thus it was determined thataustenite start (As) temperature is 23.5 oC, austenite finish (Af) temperature is 50.6 oC, martensite start (Ms)temperature is 26.7 oC and martensite finish (Mf) temperature is -0.10 oC. For different heating rate of DSCmeasurements, it was observed that martensite to austenite phase transformation temperatures (As and Af) arechanged, while it did not effect on the reversible martensite phase transformation temperature (Ms and Mf). Thermalactivation energy of the alloy was measured by Kissinger method, which is Ea=63.208 kJ/mol. Moreover, Gibbsfree energy was slightly increased with increasing heating-cooling rates. The DSC curves and XRD crystal analysisshowed the phase transformation was occurred in a single step B2 ↔B19. Beside, some precipitations like Ti2(Ni,Cu) as well as matricesin the form of TiNi0.8Cu0.2 of element Cu dissolved in interphases of NiTi were encountered.SEM-EDX was used to determine chemical composition of Ti2(Ni, Cu) phase in atomic percentage (at.%). Themicrohardness of the alloy was 219 HV, where Cu element was added to makes alloy to be softer than thetraditional binary NiTi alloys.

PDF

___

[1] Lin K.N., Wu S.K., Tsai C.L. 2008. The Effect of Thermal Cycling on B2→B19→B19' Transformations of Ti50Ni40Cu10 Shape Memory Alloy by Dynamic Mechanical Analyzer. Materials Transactions, 49 (12): 2776-2780.
[2] Gil F.J., Solano E., Pena J., Engel E., Mendoza A., Planell J.A. 2004. Microstructural, mechanical and citotoxicity evaluation of different NiTi and NiTiCu shape memory alloys. Journal of Materials Science: Materials in Medicine, 15 (11): 1181-1185.
[3] Fan G., Zhou Y., Otsuka K., Ren X., Nakamura K., Ohba T., Suziki T., Yoshida I., Yin F. 2006. Effects of frequency, composition, hydrogen and twin boundary density on the internal friction of Ti50Ni50−xCux shape memory alloys. Acta Materialia, 54 (19): 5221-5229.
[4] Ohba T., Taniwaki T., Miyamoto H., Otsuka K., Kato K. 2006. In situ observations of martensitic transformations in Ti50Ni34Cu16 alloy by synchrotron radiation. Materials Science and Engineering: A, 438-440: 480-484.
[5] Morakabati M., Aboutalebi M., Kheirandish Sh., Karimi T.A., Abbasi S.M. 2011. Hot tensile properties and microstructural evolution of as cast NiTi and NiTiCu shape memory alloys. Materials & Design, 32 (1): 406-413.
[6] Tang W., Sandström R., Wei Z.G., Miyazaki S. 2000. Experimental investigation and thermodynamic calculation of the Ti-Ni-Cu shape memory alloys. Metallurgical and Materials Transactions A, 31 (10): 2423-2430.
[7] Lee J.H., Nam T.H., Ahn H.J., Kim Y.W. 2006. Shape memory characteristics and superelasticity of Ti–45Ni–5Cu alloy ribbons. Materials Science and Engineering: A, 438-440: 691-694.
[8] Nam T.H., Saburi T., Shimizu K. 1990. Cu-Content Dependence of Shape Memory Characteristics in Ti-Ni-Cu Alloys. Materials Transactions, JIM, 31 (11): 959-967.
[9] Nam T.-H., Noh J.P., Hur S.G., Kim J.S., Kang S.B. 2002. Phase Transformation Behavior and Shape Memory Characteristics of Ti-Ni-Cu-Mo Alloys. Materials Transactions, 43 (5): 802-808.
[10] Morakabati M., Kheirandish Sh., Aboutalebi M., Karimi T.A., Abbasi S.M. 2010. The effect of Cu addition on the hot deformation behavior of NiTi shape memory alloys. Journal of Alloys and Compounds, 499 (1): 57-62.
[11] Colombo S., Cannizzo C., Gariboldi F., Airoldi G. 2006. Electrical resistance and deformation during the stress-assisted two-way memory effect in Ni45Ti50Cu5 alloy. Journal of Alloys and Compounds, 422 (1-2): 313-320.
[12] Otsuka K., Ren X. 1999. Recent developments in the research of shape memory alloys. Intermetallics, 7 (5): 511-528.
[13] Luo Y.Y., Zhao Y.Q., Lu Y.F., Xi Z.P., Zeng W.D. 2013. Microstructure and damping characteristics of Ti50Ni24.9Cu25Y0.1 shape memory alloy. Materials Letters, 95: 125-127.
[14] Liu M.Y., Qi W.Y., Tong Y.X., Tian B., Chen F., Li L. 2018. Study of martensitic transformation in TiNiCuNb shape memory alloys using dynamic mechanical analysis. Vacuum, 155: 358-360.
[15] Kim W.C., Kim Y.J., Kim J.S., Na M.Y., Kim W.T., Kim D.H. 2019. Correlation between the thermal and superelastic behavior of Ni50-xTi35Zr15Cux shape memory alloys. Intermetallics, 107: 24-33.
[16] Nespoli A., Villa E., Passaretti F. 2019. Effect of annealing on the microstructure of Yttriumdoped NiTiCu shape memory alloys. Journal of Alloys and Compounds, 779: 30-40.
[17] Meng X.L., Li H., Cai W., Hao S.J., Cui L.S. 2015. Thermal cycling stability mechanism of Ti50.5Ni33.5Cu11.5Pd4.5 shape memory alloy with near-zero hysteresis. Scripta Materialia, 103: 30- 33.
[18] Sun K., Yi X., Sun B., Gao W., Wang H., Meng X., Cai W., Zhao L. 2019. The effect of Hf on the microstructure, transformation behaviors and the mechanical properties of Ti-Ni-Cu shape memory alloys. Journal of Alloys and Compounds, 772: 603-611.
[19] Miyamoto H., Taniwaki T., Ohba T., Otsuka K., Nishigori S., Kato K. 2005. Two-stage B2–B19– B19′ martensitic transformation in a Ti50Ni30Cu20 alloy observed by synchrotron radiation. Scripta Materialia, 53 (2): 171-175.
[20] Fabregat-Sanjuan A., Ferrando F., De la Flor S. 2015. Influence of Heat Treatment on Internal Friction Spectrum in NiTiCu Shape Memory Alloy. Materials Today: Proceedings, 2: 755-S758.
[21] Goryczka T., Humbeeck J. 2006. Characterization of a NiTiCu shape memory alloy produced by powder technology. Journal of Achievements in Materials and Manufacturing Engineering, 17 (1-2): 65-68.
[22] Wang Z.G., Zu X.T., Huo Y. 2005. Effect of heating/cooling rate on the transformation temperatures in TiNiCu shape memory alloys. Thermochimica Acta, 436 (1-2): 153-155.
[23] Zengin R., Ozgen S., Ceylan M. 2004. Oxidation behaviour and kinetic properties of shape memory CuAlxNi4 (x=13.0 and 13.5) alloys. Thermochimica Acta, 414 (1): 79-84.
[24] Yildiz K., Balci E., Akpinar S. 2017. Quenching media effects on martensitic transformation, thermodynamic and structural properties of Cu–Al–Fe–Ti high-temperature shape memory alloy. Journal of Thermal Analysis and Calorimetry, 129 (2): 937-945.
[25] Nurveren K., Akdoğan A., Huang W.M. 2008. Evolution of transformation characteristics with heating/cooling rate in NiTi shape memory alloys. Journal of Materials Processing Technology, 196 (1-3): 129-134.
[26] Dagdelen F., Kok M., Qader I. 2019. Effects of Ta Content on Thermodynamic Properties and Transformation Temperatures of Shape Memory NiTi Alloy. Metals and Materials International, https://doi.org/10.1007/s12540-019-00298-z: 1-8.
[27] Kök M., Ahmed Zardawi H.S., Qader I.N., Kanca M.S. 2019. The effects of cobalt elements addition on Ti2Ni phases, thermodynamics parameters, crystal structure and transformation temperature of NiTi shape memory alloys. The European Physical Journal Plus, 134 (5):197.
[28] Qader I.N., Kök M., Dağdelen F. 2019. Effect of heat treatment on thermodynamics parameters, crystal and microstructure of (Cu-Al-Ni-Hf) shape memory alloy. Physica B: Condensed Matter, 553: 1-5.
[29] Ramaiah K.V., Saikrishna C.N., Gouthama, Bhaumik S.K. 2014. Ni24.7Ti50.3Pd25.0 high temperature shape memory alloy with narrow thermal hysteresis and high thermal stability. Materials & Design (1980-2015), 56: 78-83.
[30] Kök M., Yakinci Z.D., Aydoğdu A., Aydoğdu Y. 2014. Thermal and magnetic properties of Ni51Mn28.5Ga19.5B magnetic-shape-memory alloy. Journal of Thermal Analysis and Calorimetry, 115 (1): 555-559.
[31] Dagdelen F., Ercan E. 2014. The surface oxidation behavior of Ni–45.16%Ti shape memory alloys at different temperatures. Journal of Thermal Analysis and Calorimetry, 115 (1): 561-565.
[32] Acar E. 2016. TiNi akıllı alaşımlarında faz dönüşüm özellikleri. Gazi Üniversitesi Fen Bilimleri Dergisi Part C: Tasarım ve Teknoloji, 4 (3): 165-171.
[33] de Araújo C.J., da Silva N.J., Da Silva M.M., Gonzalez C.H. 2011. A comparative study of Ni– Ti and Ni–Ti–Cu shape memory alloy processed by plasma melting and injection molding. Materials & Design, 32 (10): 4925-4930.
[34] Thomasová M., Seiner H., Sedlak P., Frost M., Sevcik M., Szurman I., Kocich R., Drahokoupil J., Sittner P., Landa M. 2017. Evolution of macroscopic elastic moduli of martensitic polycrystalline NiTi and NiTiCu shape memory alloys with pseudoplastic straining. Acta Materialia, 123: 146-156.