engleski

The properties of shape memory alloys CuAlNi after continuous casting

In this work, the results of microstructure and phase transformation of the Cu-Al-Ni shape memory alloy (SMA) were presented. The alloy was tested by optical microscopy, using scanning electron microscopy and the differential scanning calorimetry (DSC) methods. Also hardness was measured. Samples for analysis are obtained using induction melting in the vacuum furnace. Remelted alloy is continuous casted by means of vertical device for casting in the cylindrical rods with diameter 16 mm at different speed of casting (255- 625 mm/min.). After cooling of the alloy the martensite phase primary as the needle-like into grains was observed. The columnar structure is presented near the outer surface of the samples. The As, Af, Ms and Mf temperatures are determined by the DSC method. It was found that, if the speed of casting increases then the grain size decreases. Also, the average grain diameter at the external surface and into the center are different. It was found that the average grain diameter near to the external surface was 489-229 mm, while into the center it was 212-182 mm.

shape memory alloys ; microstructure ; martensite ; hardness

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