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Texture analysis of hot rolled Ni-Mn-Ga alloys

Henryk Morawiec ,  Tomasz Goryczka ,  Krystian Prusik ,  Andrzej Drdzeń ,  Jozef Lelatko 

University of Silesia, Institute of Materials Science, 12, Bankowa Str., Katowice 40-007, Poland

Abstract

One of the important factor which controls the MSM effect is the magneto-crystalline anisotropy of the martensite with the c/a<1.  A crystallographic texture of the polycrystalline alloy can significantly improve this effect. The preferred orientation is the <001> direction which is the easy magnetization direction.

The studies were carried out on two Ni-Mn-Ga polycrystalline alloys with the 10M martensite structure. The specimens were cut along the [001] and [110] directions of the columnar grains  from the ingots of either round or flat shape. The rolling was carried out on the samples imbedded in steel channel bar and “sealed” in a flat pipe. The samples were heated up to 10000C and rolled in one direction in several steps. Before each step the sample was reheated. The final reduction of the samples thickness was: 28%, 36%, 57% and 69%.

The texture was studied by the EBSD and X-ray diffraction using the {001}, {110} and {111} pole figures.

The texture of the initial [001] orientation rolled with the highest deformation 60% shows the following orientation components: {111}<011>, {111}<112>, {112}<011>  which are typical for deformed and recrystallized metals of the A2 structure. The presence of the {011}<100> components was not stated. The texture of the specimen with the initial [110] orientation rolled with  69% can be described as a fibre texture scattered along the <110> direction. This kind of texture for the rolled samples of the A2 structure is also known in the praxis. As a conclusion one can state that the hot rolling of the Ni-Mn-Ga alloys is not efficient to produce the texture with [001] orientation.

 

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Related papers

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

Submitted: 2008-05-09 12:23
Revised:   2009-06-07 00:48