Effect of Ta Additions on the Microstructure, Damping, and Shape Memory Behaviour of Prealloyed Cu-Al-Ni Shape Memory Alloys

Abstract

The influence of Ta additions on the microstructure and properties of Cu-Al-Ni shape memory alloys was investigated in this paper. The addition of Ta significantly affects the green and porosity densities; the minimum percentage of porosity was observed with the modified prealloyed Cu-Al-Ni-2.0 wt.% Ta. The phase transformation temperatures were shifted towards the highest values after Ta was added. Based on the damping capacity results, the alloy of Cu-Al-Ni-3.0 wt.% Ta has very high internal friction with the maximum equivalent internal friction value twice as high as that of the prealloyed Cu-Al-Ni SMA. Moreover, the prealloyed Cu-Al-Ni SMAs with the addition of 2.0 wt.% Ta exhibited the highest shape recovery ratio in the first cycle (i.e., 100% recovery), and when the number of cycles is increased, this ratio tends to decrease. On the other hand, the modified alloys with 1.0 and 3.0 wt.% Ta implied a linear increment in the shape recovery ratio with increasing number of cycles. Polarization tests in NaCl solution showed that the corrosion resistance of Cu-Al-Ni-Ta SMA improved with escalating Ta concentration as shown by lower corrosion current densities, higher corrosion potential, and formation of stable passive film.

Dynamic mechanical damping analysis of up/step-quenched Cu-Zn-Sn-based shape memory alloys

“…The damping capacity of a material can thus be determined precisely in terms of the loss tangent (Tan δ) signal recorded over a period of time [44]. Tan δ attains peak as a result of the internal friction associated with martensitic transformations in SMAs [45].…”

Revisiting Cu-based shape memory alloys: Recent developments and new perspectives

“…Other several additions of elements were reported in the literature, such as Cu-Al-Ni -Hf [6], Cu-Al-Ni-Ta [87], Cu-Al-Ni-Fe [88,89], Cu-Al-Ni -Zn [11], Cu-Al-Ni-Cr [90], Cu-Al-Ni-Ti-Cr [91], Cu-Al-Ni-V[92] and Cu-Al-Ni-Sn [93].…”

Investigations on the actuation behaviour of friction stir–welded nickel titanium shape memory alloy using continuous fibre laser

“…The reduced damping ability of the weld could be attributed to changes in microstructure, micro-defect density, dislocation density, etc., after welding. [20][21][22][23]…”