engleski

Properties of Cu-Al-Ni shape memory alloys

Two different casting techniques were used for production the Cu-Al-Ni shape memory alloys (SMAs) directly from the melt. By melt-spinning technique the ribbons are produced, while by continuous casting technique the strands with diameter of 16 mm are fabricated. The microstructure characterization of ribbons and cast strands was carried out after solidification. Non-depending from casting techniques of the alloys the martensite phase primary as the needle-like into grains was observed. Phases beta1` and beta1 are observed by XRD method. The temperature transformation (As, Af, Ms and Mf) are determined by DSC method. It was found that grains size of continuous casted strands is considerably higher than that the melt-spinning ribbons. An average grain size of ribbons varied from 44 mikrometer at average number of grains of 417/mm2. The average grain diameter at the external surface and into the center of strands are different (average grain diameter near the external surface was 489-229 mm, while into the center it was 212-182 mm). The present work shows that the grain size and transformation temperatures of the alloy considerable change with the technology for production of SMAs. Non-depending from production technique of Cu- Al-Ni alloy the martensite microstructure was obtained as base for shape memory effect.

shape memory alloys ; Cu-Al-Ni alloys ; martensite ; melt-spinning ; continuous casting

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