Estudo da histerese térmica de ligas Cu-Al-Mn-Ti-B com efeito memória de forma

Abstract

In recent years, interest in alloys with low superelasticity shape memory has been increasing. The percentage of stress-induced martensite, not recovered after the release of mechanical loading, has been thermally converted to achieve industrial applications. In this work, the influence of the deformation velocity and the temperature on the residual deformation of Cu-Al-Mn alloys, modified with the addition of Ti-B, capable of the shape memory effect, were evaluated for their use in bonding devices of low processing cost. The alloys were prepared without atmosphere control and were characterized microstructurally via optical microscopy, differential scanning calorimetry, scanning electron microscopy and X-ray diffraction. The thermomechanical properties were evaluated by static tensile and cyclic loading / unloading tests. The results showed that the alloy has a completely austenitic phase at room temperature, presenting a structure of type L21. It was found that martensitic transformation tensions increased with higher loading speeds, as well as residual deformation. The average value of ruptured deformation was approximately 13%. Regarding the variation of the imposed deformation percentage, the superelasticity decreased as the percentage was increased and the residual deformation increased. The results presented indicate the viability of Cu-8.15Al-10.71Mn-0.43Ti-0.086B alloy for applications requiring alloys with high thermal hysteresis.