J. Phys. IV France 112 (2003) 605
DOI: 10.1051/jp4:2003958

In situ study of the phase decomposition process in a Cu-Al-Ni shape memory alloy processed by powder metallurgy

V. Recarte¹, J.I. Pérez-Landazabal¹, J. Campo², R.B. Pérez-Saez³, M.L. No⁴ and J. San Juan<sup>3

1</sup>  Departamento de Fisica, Universidad Publica de Navarra, Campus de Arrosadia s/n, 31006 Pamplona, Spain
²  institut Laue Langevin, 6 rue J. Horowitz, BP. 156, 38000 Grenoble, France
³  Departamento de Fisica Materia Condensada, Facultad de Ciencias, Universidad del Pais Vasco/EHU, 48080 Bilbao, Spain
⁴  Departamento de Fisica Aplicada II, Facultad de Ciencias, Universidad del Pais Vasco/EHU, 48080 Bilbao, Spain

Abstract
The precipitation of the stable phases in Cu-Al-Ni shape memory alloys (SMA) limits the maximum using temperature since the decomposition of phase degrades very quickly the martensitic transformation. In this paper, the precipitation processes of the metastable phase during heating in a Cu-14.37 Al-4.2 Ni (wt. %) SMA processed by powder metallurgy have been studied by Differential Scanning Calorimetry (D.S.C.) and in situ neutron powder diffraction. The pro-eutectoid ; precipitation and the eutectoid decomposition has been observed during heating, followed by the posterior dissolution at higher temperature. The transformation temperatures have been determined by D.S.C. The Rietveld analysis performed on the neutron diffraction spectra allows to determine the volume fraction of the different precipitated phases and their evolution during heating. The activation energy of the primary , precipitation has been determined.

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