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 (T_on), angle of cut (A_C), and pulse off time (T_off). 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.

Adding alloying elements like copper (Cu) and zirconium (Zr) to binary NiTi shape memory alloys (NiTiCuZr SMA) raises the martensitic transition temperatures and functional fatigue properties while maintaining high corrosion and wear resistance. Therefore, it is essential to make high-precision SMA components with less damage to be machined into various complex shapes, sizes, and surface topographies to meet the needs of several engineering applications. In this research work, advanced machining processes like wire electrical discharge machining (WEDM) and fiber laser machining were employed to machine NiTiCuZr SMA and study their processing parameters’ effects on the surface roughness, topography changes, and surface hardness. 3D surface topography and surface roughness on the machined surfaces were evaluated through contact and non-contact measurement techniques. The differential scanning calorimetry (DSC) test was conducted on the NiTiCuZr SMA before and after machining to confirm changes in the shape memory properties. When both processes were used at high energy levels, the formation of the resolidified layer and surface defects were more pronounced, increasing surface roughness. DSC curves for heating and cooling profiles show similar transformation temperatures for WEDM and laser machined NiTiCuZr SMA. On comparing two different machining processes, the WEDM process resulted in the Ra ( μ m) being 28.2% lower, the surface topography was smooth, and the microhardness was 11.9% lower than the samples machined using laser machining. This shows that machining of NiTiCuZr SMA using WEDM gives a better surface finish, reaching a fair decision that WEDM is a better alternative to laser machining.

Objective: Friction Stir Welding (FSW) is a relatively new solid state welding technique for similar and dissimilar materials, especially on current interest with aluminum and magnesium alloys. Methods/Analysis: The Friction Stir Welding of aluminum alloys with magnesium alloys are reviewed on this paper. The basic principles of FSW are described, followed by process parameters study which affects the weld strength. Findings: The microstructure and the likelihood of defects also reviewed. Tensile strength properties attained with different process parameters are discussed. Conclusion/Application: It is demonstrated that FSW of aluminum and magnesium alloy is becoming an emerging technology with numerous commercial applications.

NiTiCuZr shape memory alloys (SMA) outperform ternary and binary SMA alloys in terms of functional fatigue and higher temperature performance due to their high cyclic stability and transformation temperatures. Owing to the impairment of the shape memory effect during processing, it is difficult to select a manufacturing process for obtaining design functionality with the required dimensions and surface roughness. In this work, a high-temperature NiTiCuZr SMA was machined using an ultrasonic vibration assisted wire electric discharge machine (USV-WEDM). The machining was conducted using various parameters with a constant ultrasonic vibration of 20 kHz provided on a wire-electrode to evaluate surface roughness (Ra) and material removal rate (MRR). Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray analysis (EDX) were utilized to examine the surface integrity and chemical composition of the machined surfaces. MRR increased by 62% with a steady increase in pulse-on time ( T _on ) and applied current ( I ), whereas increasing levels of parameters such as pulse-off time ( T _off ) and servo voltage (SV) reduced surface roughness ( R _a ) by 69%. The results reveal that tool vibration at ultrasonic frequency reduces the surface roughness and improves the material removal rate of the machined NiTiCuZr SMA as compared to that of non-ultrasonic assisted machining conditions. SEM-EDX investigation reveals that the formation of re-solidification and oxide layers during NiTiCuZr machining at high machining parameters results in increased hardness and surface roughness. USV-WEDM is a suitable process for machining SMA alloy without adversely impacting SMA properties.

Nitronic-50 stainless steel is a high-strength and corrosion-resistant austenitic premium steel. It requires improved surface characteristics due to its wide use in various applications like fasteners, marine hardware, hydroelectric-power turbines, pressure vessels, etc. This work focuses on machining hard-to-machine Nitronic-50 steel is unconventionally machined using constant frequency ultrasonic-aided low-speed wire electrical discharge machining (USV-LS-WEDM) to enhance its machined surface integrity. This method achieves effective results when cutting high-strength materials with intricate shapes. Material removal rate (MRR) and surface roughness (Ra) were measured by considering inputs such as servo voltage (SV), pulse off time ( T_off), pulse on time ( T_on) and current (I) with an ultrasonic-vibration range of 20,000 Hz. The appropriate selection and usage of LS-WEDM parameters is a challenging process and is done with parametric analysis. The MRR of Nitronic-50 was enhanced with an increase in T_on and I along with a reduction in T_off and SV. Surface roughness (Ra) decreased with a gradual reduction in T_on, I, and an increase in SV. The USV-WEDM was compared with a stand-alone WEDM indicating that the MRR for USV-WEDM was improved by 12% and the Ra was decreased by 9% due to effective distribution of spark discharges, which increased material erosion and redistribution of molten metal characteristics. Machining quality for hard-to-machine Nitronic-50 steel was certainly enhanced via hybrid ultrasonic vibration with the existing LS-WEDM.