Şekil Hafıza Davranışlarının Termodinamiği

Öz

Akıllı malzemeler bugünkü teknolojik uygulamalarda önemli bir yer tutmaktadır. Metalik akıllı malzemeler olan şekil hafızalı alaşımlar ise yüksek dayanım ve fonksiyonel özellik gerektiren uygulamalarda kullanılma potansiyeline sahiptir. Şekil hafızalı alaşımların sıradışı özellikleri, termo-elastik martenzitik faz dönüşümlerinden kaynaklanmaktadır. Bu çalışmada, termo-elastik martenzitik faz dönüşümleri konusunda yapılmış çalışmalarda kullanılan termodinamik teorileri, denge termodinamik teorisi ve fenomolojik termodinamik teorisi olarak iki ana başlık altında incelenmiştir. Daha sonra şekil hafızalı alaşımların dönüşüm sıcaklıkları ve ısıları termodinamik formüller ile ifade edilmiştir. Son olarak ise şekil hafızalı alaşımların davranışları genelleştirilmiş termodinamik teorileri ile açıklanmıştır. 

Anahtar Kelimeler

• Şekil hafızalı alaşım,termodinamik,faz dönüşümü

Thermodynamics of Shape memory Behaviours

Öz

Smart materials play important roles in today’s technology. Shape memory alloys are metallic class of smart materials and they have promising potentials in applications that require high strength and functionality. The origin of the unusual properties of shape memory alloys is thermo-elastic martensitic phase transformation. In this study, thermodynamic theories used in analyzing the thermo-elastic martensitic phase transformations are reviewed by considering equilibrium thermodynamic theory and phonemenological thermodynamic theory. Then, transformation temperatures and heats are expressed by thermodynamic equations. Finally, shape memory behaviors are investigated by generalized thermodynamic theories.

Anahtar Kelimeler

• Shape memory alloy,thermodynamics,phase transformation

Kaynakça

1. [1] Wayman, C.M. and Otsuka,K. Shape Memory Materials. Cambridge University Press, (1998).
2. [2] Acar,E., Ozbulut, O.E. and Karaca,H.E. “Experimental investigation and modeling of the loading rate and temperature dependent superelastic response of a high performance shape-memory alloy,” Smart Mater. Struct., 24; 7, 75020, (2015).
3. [3] Karaca,H.E., Acar,E., Ded,G.S.,Saghaian,S.M.,Basaran,B.,Tobe,H., Kok,M. Maier,H.J., Noebe,R.D. and Chumlyakov,Y.I. “Microstructure and transformation related behaviors of a Ni45.3Ti29.7Hf20Cu5 high temperature shape memory alloy,” Mater. Sci. Eng. A, 627; 82–94, (2015).
4. [4] Karaca,H.E.,Acar,E.,Basaran,B.,Noebe,R.D., Bigelow,G., Garg,A., Yang,F., Mills, M.J. and Chumlyakov, Y.I.“Effects of aging on [111] oriented NiTiHfPd single crystals under compression,” Scr. Mater., 67; 7, 728–731, (2012).
5. [5] Karaca,H.E., Acar,E., Ded,G.S.,Basaran,B., Tobe,H., Noebe,R.D.,Bigelow,G., and Chumlyakov,Y.I. “Shape memory behavior of high strength NiTiHfPd polycrystalline alloys,” Acta Mater., 61; 13,5036–5049, (2013).
6. [6] Lin,H.C., Wu,S.K., Chou,T.S. and Kao,H.P. “The effects of cold rolling on the martensitic transformation of an equiatomic TiNi alloy,” Acta Metall. Mater., 39; 9, 2069–2080, (1991).
7. [7] Acar,E., Karaca,H.E.,Tobe,H., Noebe,R.D. and Chumlyakov,Y.I. “Orientation dependence of the shape memory properties in aged Ni45.3Ti29.7Hf20Pd5 single crystals,” Intermetallics, 54; 60–68, (2014).
8. [8] Karaca,H.E., Acar,E.,Basaran,B., Noebe,R.D. and Chumlyakov,Y.I. “Superelastic response and damping capacity of ultrahigh-strength [111]-oriented NiTiHfPd single crystals,” Scr. Mater., 67;5, 447–450, (2012).

9. [9] Acar, E.,Tobe,H., Kaya, I.Karaca,H.E. and Chumlyakov,Y.I., “Compressive response of Ni45.3Ti34.7Hf15Pd5 and Ni45.3Ti29.7Hf20Pd5 shape-memory alloys,” J. Mater. Sci.,50;4,1924–1934, (2015).
10. [10] Liu,Y. and Yang,H. “The concern of elasticity in stress-induced martensitic transformation in NiTi,” Mater. Sci. Eng. A, 260;1, 240–245, (1999).
11. [11] Wollants, P.,Roos, J.R. and Delaey,L., “Thermally- and stress-induced thermoelastic martensitic transformations in the reference frame of equilibrium thermodynamics,” Prog. Mater. Sci., 37;3, 227–288, (1993).
12. [12] McCormick,P.G. and Liu,Y. “Thermodynamic analysis of the martensitic transformation in NiTi—II. Effect of transformation cycling,” Acta Metall. Mater., 42; 7,2407–2413, (1994).
13. [13] Ortín,J. and Planes, A.“Thermodynamic analysis of thermal measurements in thermoelastic martensitic transformations,” Acta Metall., 36; 8, 1873–1889, (1988).
14. [14] Acar,E. “Precipitation, orientation and composition effects on the shape memory properties of high strength NiTiHfPd alloys,” University of Kentucky, (2014).
15. [15] Kaya, I., Tobe,H., Karaca, H.E.,Acar,E. and Chumlyakov,Y.I. “Shape Memory Behavior of [111]-Oriented NiTi Single Crystals After Stress-Assisted Aging,” Acta Metall. Sin. English Lett., 29;3, 282–286, (2016).
16. [16] Tong,H.C. and Wayman,C.M. “Characteristic temperatures and other properties of thermoelastic martensites,” Acta Metall., 22;7, 887–896, (1974).
17. [17] Lagoudas, D.C. and Kumar,P.K. “Introduction to Shape Memory Alloys,” in Shape Memory Alloys, Springer,1–51,(2008).
18. [18] Tong, H.C. and Wayman,C.M. “Thermodynamics of thermoelastic martensitic transformations,” Acta Metall., 23; 2,209–215, (1975).
19. [19] Liu, Y. “Thermodynamics of the shape memory effect in Ti–Ni alloys,” in Shape memory Alloys for Biomedical Applications, T. Y. and S. Miyazaki, Ed. Woodhead Publishing, (2009).
20. [20] Wollants,P., Roos, J.R. and Delaey,L. “On the stress-dependence of the latent heat of transformation as related to the efficiency of a work performing cycle of a memory engine,” Scr. Metall.,14;11,1217–1223, (1980).
21. [21] Wollants,P., De Bonte, M. and Roos,J.R. “Comments on ‘The transformation free energy in ordered Fe3Pt,”’ Scripta Metallurgica, 17; 5. Pergamon, 671–672, (1983).
22. [22] Salzbrenner,R.J. and Cohen,M. “On the thermodynamics of thermoelastic martensitic transformations,” Acta Metall., 27;5,739–748, (1979).
23. [23] Olson,G.B. and M. Cohen, M.“Thermoelastic behavior in martensitic transformations,” Scr. Metall., 9;11,1247–1254, (1975).
24. [24] Salzbrenner,R.J. and Cohen,M. “On the thermodynamics of thermoelastic martensitic transformations,” Acta Metall., 27;5,739–748, (1979).
25. [25] Khalil-Allafi,J., Dlouhy,A. and Eggeler,G. “Ni4Ti3-precipitation during aging of NiTi shape memory alloys and its influence on martensitic phase transformations,” Acta Mater., 50;17,4255–4274, (2002).
26. [26] Ortín,J. and Planes,A. “Thermodynamics of thermoelastic martensitic transformations,” Acta Metall., 37;5,1433–1441, (1989).
27. [27] Liu,Y. and McCormick,P.G. “Thermodynamic analysis of the martensitic transformation in NiTi—I. Effect of heat treatment on transformation behaviour,” Acta Metall. Mater.,42; 7, 2401–2406, (1994).
28. [28] Wayman,C.M. and Tong,H.C. “On the equilibrium temperature in thermoelastic martensitic transformations,” Scr. Metall., 11; 5,341–343, (1977).
29. [29] Stachowiak,G.B. and McCormick,P.G., “Shape memory behaviour associated with the R and martensitic transformations in a NiTi alloy,” Acta Metall., 36; 2, 291–297, (1988).
30. [30] Stachowiak,G.B. and McCormick, P.G.“Two stage yielding in a NiTi alloy,” Scr. Metall., 21;3, 403–406, (1987).
31. [31] Kakeshita, T.,Saburi,T. and Shimizu, K.“Effects of hydrostatic pressure and magnetic field on martensitic transformations,” Mater. Sci. Eng. A, 273;21–39, (1999).
32. [32] Zhang,S. and McCormick,P.G. “Thermodynamic Analysis of Shape Memory Phenomena — II. Modelling,” Acta Mater., 48;12,3091–3101, (2000).
33. [33] Zhang,S. and McCormick,P.G. “Thermodynamic analysis of shape memory phenomena — I. Effect of transformation plasticity on elastic strain energy,” Acta Mater., 48; 12, 3081–3089, (2000).
34. [34] Mur, G., Javier,F. “Friction and stored elastic energy in Cu-Zn-A1 single crystals with pseudoelastic behaviour,” Thermochim. Acta, 290;2,167–171, (1997).
35. [35] Acar, E.,Karaca,H.E., Basaran, B.,Yang,F.,Mills,M.J.,Noebe,R.D. and Chumlyakov,Y.I. “Role of aging time on the microstructure and shape memory properties of NiTiHfPd single crystals,” Mater. Sci. Eng. A, 573;161–165, (2013).
36. [36] Acar, E.,Karaca,H.E., Tobe,H., Noebe,R.D. and Chumlyakov,Y.I. “Characterization of the shape memory properties of a Ni45.3Ti39.7Hf10Pd5 alloy,” J. Alloys Compd., 578; 297–302, (2013).
37. [37] Karaca, H.E.,Saghaian,S.M., Tobe, H.,Acar, E.,Basaran, B.,Nagasako,M., Kainuma,R. and Noebe,R.D. “Diffusionless phase transformation characteristics of Mn75.7Pt24.3,” J. Alloys Compd., 589; 412–415, (2014).
38. [38] Nishida,M.,Wayman,C.M. and Honma,T. “Precipitation processes in near-equiatomic TiNi shape memory alloys,” Metall. Trans. A, 17;9, 1505–1515, (1986).
39. [39] Tong,H.C. and Wayman,C.M. “Some stress-temperature-energy relationships for thermoelastic martensitic transformations,” Scr. Metall., 8;2,93–100, (1974).
40. [40] Shimizu,K. and Kakeshita,T. “Effect of Magnetic Fields on Martensitic Transformations in Ferrous Alloys and Steels,” ISIJ Int., 29; 97–116, (1989).