Shape memory properties and microstructural evolution of rapidly solidified CuAlBe alloys

In this work, the effects of Be addition on the microstructure and phase transformation temperatures of Cu–12Al–xBe (x = 0.4, 0.5 and 0.6 wt.%) shape memory alloys fabricated by using the arc-melting and melt-spinning techniques have been investigated. X-ray diffraction analysis revealed that the arc-melted alloys consisted of austenitic β1, martensitic β1′ and γ2 precipitate phases, whereas melt-spun ribbons were composed of a fully martensitic phase. The average grain size of martensitic phases in melt-spun ribbons was determined by electron microscopy images, showing a decrease with increasing Beryllium (Be) amount. Moreover, it was found that the Be addition in the arc-melted alloys had a distinct effect on the morphology of the γ2 precipitate phase. Transmission electron microscopy analysis showed that the thickness of martensitic plates in the melt-spun ribbons reduced with increasing Be addition. In a differential scanning calorimeter analysis, no martensitic transformation (Ms) peak was observed in arc-melted alloys, but it was clearly detected in melt-spun ribbons, in which Ms decreased dramatically with increasing Be addition. The improvement in the shape memory ability of melt-spun ribbons was explained in terms of the refinement in grain size and martensitic plates. - Highlights: • The CuAlBe SMAs were produced by means of arc-melter and melt-spinner techniques. • MT was directly obtained in melt-spuns without any intermediate process. • The transformation temperatures decreased with increasing Be amount. • The thickness of martensitic plates in the ribbons reduced with increasing Be. • SMP of CuAl was improved by the addition of Be together with rapid solidification