Theoretical Prediction on Martensitic Transformation Start-Strain of Nitinol

The martensitic phase transformation (MT) start-strain of NiTi shape memory alloy under uniaxial tension is predicted theoretically on the basis of micromechanics. Results directly show that the martensitic transformation start-strain depends on three kinds of parameters: lattice correspondence strain (Bain strain), mechanical constants of Nitinol (Youngʹs module, Poisson ratio) and chemical energy difference between austenite and martensite phase (temperature dependence parameters). Comparison of this new prediction with other methods and experimental data is also given.