Investigations were made of ultrasonic strain-amplitude dependent internal friction, and of the effect of ultrasonic vibration upon the macroplastic strain (acoustoplastic effect), during the deformation of quenched single crystals of the β1' martensite phase. The effect of the macroscopic plastic strain rate upon the amplitude dependent internal friction and acoustoplastic effect, as well as the kinetics of the acoustoplastic effect was studied. The results of in situ amplitude dependent internal friction measurements were compared with data on the amplitude dependent internal friction temperature dependence. The observed trends were attributed to differences in the mechanisms of macroplastic deformation in the martensitic phase. These were related to the motion of intervariant interfaces, and to reversible anelastic strain. At ultrasonic frequencies and moderate strain amplitudes, the latter was due largely to oscillatory motion of the partial dislocations. It was concluded that the dynamics of partial dislocations at 210 to 300K were largely governed by interactions with saturated atmospheres of mobile pins. Simultaneous measurements of the amplitude dependent internal friction and acoustoplastic effect suggested that, at high oscillatory strain amplitudes, the breaking of partial dislocations through the mobile atmospheres of pins initiated a step-like accumulation of macroplastic strain, due to the motion of intervariant boundaries.

Motion of Dislocations and Interfaces during Deformation of Martensitic Cu-Al-Ni Crystals. K.Sapozhnikov, S.Golyandin, S.Kustov, J.Van Humbeeck, R.De Batist: Acta Materialia, 2000, 48[5], 1141-51