Microstructure and magnetic properties of two phase b+g ferromagnetic Co-Ni-Al alloys

Wojciech Maziarz 1Jan M. Dutkiewicz 1Marcin Leonowicz 2Rafał Wróblewski 2

1. Polish Academy of Sciences, Institute of Metallurgy and Materials Sciences (IMIM PAN), Reymonta 25, Kraków 30-059, Poland
2. Warsaw University of Technology, Faculty of Materials Science and Engineering (InMat), Wołoska 141, Warszawa 02-507, Poland

Abstract

The microstructure and magnetic properties of two ferromagnetic alloys with composition as: Co35Ni37Al28 and Co37Ni35Al28 (in at. %) were investigated by optical microscopy (OM), analytical transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The plastically deformed alloys up to 45% were then heat treated in order to promote the martensitic transformation. Differential scanning calorimeter (DSC) was used for determination of characteristic temperatures of transformation, and it was observed a drop of Ms temperature due to the increase of Co content in alloys. The elongated twined grains of size of about 200 mm and small precipitation of g phase has been identified by OM techniques. TEM observations allowed identifying the L10 non modulated martensite within elongated grains and small amount of ordered g (g’) was still observed after heat treatment. The elemental mapping technique and chemical point analyses allowed determining the composition of particulate phases. The VSM measurements performed for two directions of samples i.e. parallel and perpendicular to the rolling direction, allowed determining the phase transition temperatures, Curie temperature and basic magnetic properties of investigated alloys.

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Presentation: Oral at E-MRS Fall Meeting 2008, Symposium C, by Wojciech Maziarz
See On-line Journal of E-MRS Fall Meeting 2008

Submitted: 2008-05-19 14:12
Revised:   2009-06-07 00:48
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