Internal friction due to ϵ → γ reverse transformation in an FeMnSiCr shape memory alloy

Abstract Internal friction due to h.c.p. → f.c.c. (ϵ → γ) reverse transformation in an FeMnSiCr alloy has been examined after introducing h.c.p. martensite by pre-deformation at room temperature. A clear internal friction peak is detected during the ϵ → γ reverse transformation. It is shown that the integral of the logarithmic decrement multiplied by the vibrational frequency with respect to temperature between the transformation starting and finishing temperatures is proportional to the amount of the h.c.p. martensite formed by the pre-deformation. The height of the internal friction peak linearly depends on heating rate. These observations are discussed by considering the stress-assisted or retarded motion of Shockley partial dislocations which constitute an interface between the martensite and matrix.

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