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Developing shape-memory materials using fast acting cyclic stresses for memory stabilizing

I. S. RADU1,* , S. VLASE1, M. R. CALIN2

Affiliation

  1. Transilvania University of Brasov, 29 Eroilor Blvd, Code 500036, Brasov, Romania
  2. ”Horia Hulubei” National Institute for Physics and Nuclear Engineering - IFIN HH, P.O. Box MG-6, 077125, Magurele, Romania

Abstract

Shape-memory alloys are intelligent materials, with a high density of energy and the ability to “remember” their initial shape when subjected to a plastic deformation. The shape-memory effect can be defined as a reversible thermoelastic martensitic transformation. This phenomenon is enabled by a bidirectional transformation of the crystal phase, from martensite to austenite, under the effect of heat. During the transformation phase non-recoverable plastic deformations may occur, limiting the memory effect. A method to reduce remanent plastic strain and stabilize the memory effect (also known as the training of the memory-effect) is to apply cyclic thermomechanical stresses at constant load or temperature on the memory-material. This paper presents a concrete procedure and an experimental device developed for training memory effect samples. The memory effect of a Ni-Ti alloy sample was measured before and after the sample was trained. A gain of 15 % in memory effect was determined, between the trained and the untrained material sample..

Keywords

Shape-memory alloys, Thermomechanical training, Intelligent materials, Memory effect.

Citation

I. S. RADU, S. VLASE, M. R. CALIN, Developing shape-memory materials using fast acting cyclic stresses for memory stabilizing, Optoelectronics and Advanced Materials - Rapid Communications, 8, 3-4, March-April 2014, pp.251-254 (2014).

Submitted at: March 4, 2013

Accepted at: March 13, 2014