Internal friction behavior of the reverse martensitic transformation in deformed MnCu alloy

In order to study the reverse transformation dynamics of MnCu alloys with deformed martensitic phase, the temperature dependence of internal friction (IF) is measured under various heating rates and vibration frequencies, while the deformed martensite microstructure of the alloy is observed with scanning electron microscopy and electron backscatter diffraction at room temperature. It is found that variant reorientation of twinning martensite is induced by the applied tensile stress through detwinning and diminishing of unfavorable orientation. Meanwhile, the IF peak occurring during the reverse transformation shows different nonlinear relationships to heating rate and vibration frequency, when the martensite microstructure is deformed to different plastic strains. The coefficient n and l describing the transformation dynamics are determined from the heating rate and frequency dependent IF peaks, and the variation as well as the physical meaning of the coefficients corresponding to the changes in martensite microstructure are discussed.