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Study of precipitate formation in Cu–Al–Ni–Mn–Fe shape memory alloys

S. STANCIU1, L.-G. BUJOREANU1,* , BURAK ÖZKAL2, M. LUTFI ÖVEÇOĞLU2, ANDREI VICTOR SANDU1,3

Affiliation

  1. Faculty of Materials Science, the “Gh.Asachi” Technical University from Iaşi, Bd.D.Mangeron 61A, 700050 Iaşi, Romania
  2. Istanbul Technical University, Metallurgical and Materials Engineering Department PML LAB. 34469 Maslak – Istanbul, Turkey
  3. Romanian Inventors Forum, Str. Sf. P.Movilă, 3, 700089, Iaşi, Romania

Abstract

The paper analyses the precipitation of γ2 phase within the γ’1 thermally induced martensitic matrix of five Cu-Al-Ni-Fe-Mn shape memory alloys (SMAs), by means of differential scanning calorimetry (DSC) thermograms, optical microscopy (OM) and scanning electron microscopy (SEM). It has been proved that the flat exothermic peaks, occurring during the heating of martensitic specimens, correspond to the formation of γ2 phase precipitates, which are characterized by two specific morphologies, with dendrite arms at about 900 and a1200, respectively. In spite of the presence of γ2 phase precipitates, the occurrence of thermal memory has been emphasized, characterized by shape recovery degrees higher than 96 %..

Keywords

Shape memory alloys, Martensite, Phase structure, Critical temperatures, Precipitates.

Submitted at: May 5, 2008
Accepted at: June 9, 2008

Citation

S. STANCIU, L.-G. BUJOREANU, BURAK ÖZKAL, M. LUTFI ÖVEÇOĞLU, ANDREI VICTOR SANDU, Study of precipitate formation in Cu–Al–Ni–Mn–Fe shape memory alloys, Journal of Optoelectronics and Advanced Materials Vol. 10, Iss. 6, pp. 1365-1369 (2008)