Şekil Hafıza Davranışlarının Termodinamiği

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

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.

Keywords:

Shape memory alloy, thermodynamics, phase transformation,

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