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Phase evolution and microtwins in the Ni–Al multilayers upon annealing and laser mixing

Bhattacharya, P and Chattopadhyay, K and Bellon, P and Ishihara, KN (2004) Phase evolution and microtwins in the Ni–Al multilayers upon annealing and laser mixing. In: Materials Science and Engineering A, 375-37 . 1277–1284.

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Multilayers of Ni and Al of 1:1 ratio, 50 nm periodicity, were deposited using sputtering. Progress in phase evolution in these films upon annealing and laser mixing has been studied. Characterization of the as deposited and the treated states were carried out with X-ray diffraction(XRD), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) techniques. As-deposited state reveals the presence of elemental Ni and Al with grain size comparable to the film thickness. Phase evolution upon annealing occurs in several stages determined by the kinetics of nucleation and growth. $Al_3Ni$ and $Al_3Ni_2$ initially form at 673K and transforms to a mixture of AlNi and $Ni_3Al$ at about 873 K. Films were also treated with nanosecond laser pulse of 20–200 mJ energy with spot size of 1 and 1.5 mm. The major phase obtained after laser irradiation is B2 with grain size increasing with increasing imparted pulse energy. In addition to B2, microtwins and tweed microstructures are often observed. The origin and the nature of twins have been analysed in details. Formation of this type of icrostuctures in polycrystalline thin films and with Ni content <62 at.% has not been reported previously.

Item Type: Journal Article
Publication: Materials Science and Engineering A
Publisher: Elsevier
Additional Information: This article copyright belongs to Elsevier.
Keywords: Ni–Al;Multilayers;B2;L10;Microtwins;Martensite
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited: 20 Jun 2007
Last Modified: 19 Sep 2010 04:38
URI: http://eprints.iisc.ac.in/id/eprint/11206

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