Pressure-shear impact-induced phase transformations in Cu-14.44Al-4.19Ni single crystals

J. C. Escobar; R. J. Clifton

doi:10.1117/12.200917

2 February 1995 Pressure-shear impact-induced phase transformations in Cu-14.44Al-4.19Ni single crystals

J. C. Escobar, R. J. Clifton

Proceedings Volume 2427, Active Materials and Smart Structures; (1995) https://doi.org/10.1117/12.200917
Event: Symposium on Active Materials and Smart Structures: Society of Engineering Science 31st Annual Meeting, 1994, College Station, TX, United States

Abstract

Pressure-shear plate impact experiments have been carried out on Cu-14.44Al-4.19Ni (wt. %) single crystals in order to study the kinetics of the stress-induced phase transformation occurring in this shape memory alloy. In these plane wave experiments, the crystal is oriented in such a way as to activate only a single variant of martensite. The habit plane of the variant to be induced is parallel to the impact plane and shearing is parallel to the shearing direction of the transformation. Wave profiles are monitored at the rear surface of the target plate. Arrival of step-like quasi-longitudinal and quasi-shear waves are evidence of the nearly elastic response of the material. Velocity profiles provide several indications of the existence of a propagating phase boundary. The measured transverse free-surface velocity after arrival of the three elastic waves, is less than the imposed velocity at the impact plane. This velocity difference, in the absence of any evidence of plastic deformation, is indicative of a stress induced phase transformation that propagates into the crystals from the impact face. The resolved shear stress driving the transformation is approximately the same in experiments conducted at different impact angles and velocities. Velocity profiles at the rear surface of the specimen also exhibit features consistent with the interaction of the quasi-longitudinal wave with a phase boundary. Reflection of the quasi-longitudinal wave from the phase boundary results in an increase in free surface particle velocity in both the normal and transverse velocity records. The velocity profiles appear to provide an effective means for probing the kinetics of the phase transformation.

Citation Download Citation

J. C. Escobar and R. J. Clifton "Pressure-shear impact-induced phase transformations in Cu-14.44Al-4.19Ni single crystals", Proc. SPIE 2427, Active Materials and Smart Structures, (2 February 1995); https://doi.org/10.1117/12.200917

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