日本金属学会誌

J. Japan Inst. Metals, Vol. 50, No. 12 (1986),
pp. 1049-1055

An Analysis of the Mechanical Properties of Shape Memory Alloys Based on a Polycrystal Model

Noboru Ono1, Atsushi Satoh2 and Hiroyuki Ohta3

1Faculty of Engineering, Tohoku University, Sendai
2Graduate Student, Tohoku University, Sendai. Present address: Sony Magnetic-products Inc., Tagajoh
3Graduate Student, Tohoku University, Sendai

Abstract:

The scheme recently proposed by the authours on the basis of the Taylor model to deal with the deformation of polycrystals caused by the stress induced martensitic transformation (SIM) has been further extended to describe the recovery stress associated with the reverse transformation upon unloading. According to this scheme, the ``modified'' Taylor factor, M' has been calculated as a function of grain orientation for the cases of tension and compression deformation in the shape memory alloys such as CuZnAl, CuAlNi and TiNi. The results demonstrated the difference in the plastic anisotropy for SIM of grains under the polycrystalline constraint from that of isolated crystalites. The strain hardening due to the internal stresses caused by the grain orientation dependence of volume change has been shown to be insignificant in these alloys. General discussion has been given to the yield stress, recovery stress, pseudoelastic hysteresis, recovery strain, ductility, and strain hardening of the shape memory alloys, in relation to the magnitude and orientation dependence of M'.


(Received 1986/8/23)

Keywords:

stress induced martensitic transformation, pseudoelasticity, polycrystal plasticity, the Taylor model, shape memory alloys, plastic anisotropy


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