Properties of rare earth added Cu-12wt%Al-3wt%Ni-0.6wt%Ti high temperature shape memory alloy

In this study a Cu-12wt%Al-3wt%Ni-0.6wt%Ti + RE high temperature shape memory alloy, where RE denotes the rare earth doping elements, was prepared by vacuum arc melting and characterized by means of scanning electron microscopy, field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction at room and elevated temperatures, differential scanning calorimetry, tensile test and dynamic mechanical analysis. The results demonstrated that the addition of a 0.04 wt% RE to the initial alloy caused a significant grain size reduction, improved the ductility and enhanced the thermo-mechanical properties. As a consequence of the addition of RE, both the tensile fracture stress and tensile fracture strain of the alloy increased from 550 MPa and 4.50% to 660 MPa and 5.0%, respectively. The maximum recoverable strain was raised from 1.2% to 1.8%. A significant improvement of the mechanical properties and shape memory response of this alloy was attributed to the extra grain refinement mainly due to the formation of the RE-rich precipitates.