Wire-EDM machinability investigation on quaternary Ni₄₄Ti₅₀Cu₄Zr₂ shape memory alloy

摘要

Shape memory alloy (SMA), also called memory metal, is a smart material that exhibits unique shape memory effect and superelasticity properties. NiTi alloys attract researchers because of their myriad applications in areas such as aerospace, medicine, and robotics. In the present NiTi SMA fabrication, the Cu and Zr elements were added to increase the martensitic transformation temperatures. The current study focuses on the machining of high-temperature Ni44Ti50Cu4Zr2 SMA by coated wire electric discharge machining (W-EDM). Machining quality features like surface undulation and material removal were studied by considering current (I), servo voltage (SV), pulse on time (Ton), angle of cut (AC), and pulse off time (Toff). Parametric analysis of machining characteristics has been investigated by conducting experiments following the response surface approach based central composite design (RSM-CCD). It was found that MRR has increased by 57% and Ra by 58% with a gradual increase in pulse on time and applied current and decreases gradually on increasing servo voltage and pulse off time. XRD analysis reveals the presence of an oxide layer on the wire-EDMed surface. The study of SEM confirms the formation of the melted layer, micro-voids, and micro-cracks, resulting in surface irregularities.