Calculation of elastic energy contributions in single crystalline Cu-11.5wtAI-5.0wtNi shape memory alloy

摘要

Using our local equilibrium model of the martensitic transformation [1] the elastic energy contributions, as the function of martensite volume fraction,ξ, in the phase transformation of single crystalline Cu-11.5wt%Al-5.0wt%Ni shape memory alloy were calculated from our measurements published earlier [2]. The derivative of the elastic energy δE/δξ=e (E is the total elastic energy stored/released during the austenite to martensite (A→M) as well as M→A transformation) could be calculated only irrespectively of the △ST0 term (T0 is the equilibrium transformation temperature and AS is the entropy change of phase transformation). But, since △ST0 is independent of ξ, the functions obtained reflect the ξ dependence of e as well as E quantities. From the DSC curves measured at zero uniaxial stress (σ = 0) [2], the ξ-T hysteric loop was constructed. Then the e(ξ) curves at fix σ as well as fix T were calculated. The E values obtained from the integral of e(ξ), fit well to the E(σ) as well as E(T) curves calculated from the strain-temperature and stresstemperature curves measured in [2].