Abstract
As cast ingot of the polycrystalline shape memory Ni53·6Mn27·1Ga19·3 alloy was composed of columnar and equiaxed grains. Dilatation characteristics of the samples with columnar grains were studied in the temperature range of 25–370°C and compared with the dilatation characteristics of the samples with equiaxed grains. The results show that shape memory effect strongly depends on the microstructure. Preferred orientation of crystallites in the columnar structure determines its memory strain. The alloy with columnar structure was also examined after predeformation in compression. Two kinds of strains were found in the predeformed samples. Dilatation characteristics of the non-deformed and predeformed martensite show anomalous behaviour.
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