Ni-Ti shape memory alloys are well known from their wide applications, especially in medicine. Despite the fact that they can be use as short-time implants an effort is made to improve their physical properties and biocompatibility. Particularly, an attention is paid to make a way of production short as much as possible, simultaneously keeping good quality of a final product. A twin rolls casting, which belongs to the family of rapid solidification techniques, appeared to be a useful method for Ni-Ti alloy production. In addition to economical advantages of this technique unique properties of the strip can be obtained. It combines rapid solidification together with cold-rolling. In practice, the strips are ready to use in as-cast state without additional thermo-mechanical treatment, which is needed after traditional casting for inducing shape memory effect. From the point of view of the physical properties, the main advantage of this technique is preferential grains growth. Appropriate grains orientation, originated in crystallographic description of the martensitic transformation, can increase shape memory effect.

The present work summarizes results obtained from X-ray and electron back scattered diffraction carried out for polycrystalline Ni-Ti shape memory strips produced by twin rolls casting. The strips reveal presence of the reversible martensitic transformation, which occurs between the B2, high temperature, parent phase and the B19’monoclinic martensite. The crystallization front, which simultaneously proceeds from the outer parts of the strip to its centre, causes preferentially oriented grains formation. The zones, which were in direct contact with the rotating wheels, reveal shorter grains under which the long columnar grains were extending to the centre of the strip. In the outer surfaces, two kinds of the grains can be distinguishable: equiaxial - with an average grain diameter of 5um and short columnar - 20um long. Amount of the 85% grains formed in the zone close to the surface are preferentially oriented. Texture is a mixture of the fibre <001> and <011> orientations as well as the sheet texture component {001}<100>. The columnar grains formed in the inner part of the strips are about 100 um long and reveal orientation along <001> and {001}<100> textural component.

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