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On some structural characteristics of Fe-base shape memory alloys

A.-L. PARASCHIV1, F. BORZA2, N. LUPU2, M.-G. SURU1, N. M. LOHAN1, B. PRICOP1, I.-P. SPIRIDON1, L.-G. BUJOREANU1,*

Affiliation

  1. Faculty of Materials Science and Engineering, The "Gheorghe Asachi" Technical University of Iaşi, Bd. D. Mangeron 61A, 700050 Iaşi, Romania
  2. National Institute of Research and Development for Technical Physics, Bd. D. Mangeron 47, 700050, Iaşi, Romania

Abstract

Two different types of Fe-base shape memory alloys (SMAs), obtained by different processing methods, were comparatively analyzed from the point of view of: (i) structural characterization, (ii) morphologic aspects and (iii) mechanical behaviour. For this purpose, heat treated specimens of Fe-9Cr-4Ni-0.33C and in Fe-28Ni-17Co-11.5 Al-2.5 Ta (mass. %) were produced and prepared for X-ray diffraction (XRD) and scanning electron microscopy (SEM) observations, which enabled to detect the presence of α’ thermally induced martensite and γ austenite and to observed their respective morphologies. By means of micro-indentation tests, the variations of load vs. depth were recorded and the presence of pseudoelastic behaviour was confirmed, being ascribed to the presence of stable α’ martensite. When α’ martensite was stress-induced from γ austenite, being unstable upon unloading, a superelastic response was obtained, as was the case for Fe-28Ni-17Co-11.5 Al-2.5 Ta alloy..

Keywords

Martensite, XRD, SEM, Micro-indentation, Pseudoelasticity, Reversible stress-induced transformation.

Submitted at: March 25, 2013
Accepted at: July 11, 2013

Citation

A.-L. PARASCHIV, F. BORZA, N. LUPU, M.-G. SURU, N. M. LOHAN, B. PRICOP, I.-P. SPIRIDON, L.-G. BUJOREANU, On some structural characteristics of Fe-base shape memory alloys, Journal of Optoelectronics and Advanced Materials Vol. 15, Iss. 7-8, pp. 781-784 (2013)