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Article Comparative Analysis of Vibration Axis Effects on Ultrasonic Vibration-Assisted Machining of Inconel 718(MDPI, 2026) Namlu, Ramazan Hakki; Kilic, Zekai MuratInconel 718 is widely utilized in critical engineering sectors, particularly aerospace, owing to its exceptional creep resistance, corrosion resistance, and retention of mechanical strength at elevated temperatures. However, its high hardness, low thermal conductivity, and strong work-hardening tendency make it extremely difficult to machine using conventional techniques. Ultrasonic Vibration-Assisted Machining (UVAM) has emerged as an effective strategy to overcome these limitations by superimposing high-frequency, low-amplitude vibrations onto the cutting process. Depending on the vibration direction, UVAM can significantly change chip formation, tool-workpiece interaction, and surface integrity. In this study, the influence of three UVAM modes-longitudinal (Z-UVAM), feed-directional (X-UVAM), and multi-axial (XZ-UVAM)-on the machining behavior of Inconel 718 was systematically investigated. The findings reveal that XZ-UVAM provides the most advantageous outcomes, primarily due to its intermittent cutting mechanism. Compared with Conventional Machining (CM), XZ-UVAM reduced cutting forces by up to 43% and areal surface roughness by 37%, while generating surfaces with more uniform topographies and smaller peak-to-valley variations. Furthermore, UVAM enhanced subsurface microhardness as a result of the surface hammering effect, which may improve fatigue performance. XZ-UVAM also effectively minimized burr formation, demonstrating its potential for high-quality, sustainable, and efficient machining of Inconel 718.Article Effect of Aluminizing on the Oxidation of Inconel 718 and Inconel 738LC Superalloys at 925-1050 °C(MDPI, 2025) Telbakiroglu, Yusuf Burak; Konca, ErkanThis study was undertaken to investigate the effect of aluminizing on the oxidation of Inconel 718 and Inconel 738LC superalloys. Bare and high-activity chemical vapor deposition (CVD) aluminized Inconel 718 and Inconel 738LC samples were oxidized in air at 925, 1000, and 1050 degrees C for 200 h. Detailed cross-sectional examinations, elemental analyses, mass change measurements, and X-ray diffraction studies were performed. It was observed that the oxidation resistances of both alloys were significantly improved by the Al2O3 scale formed on the NiAl layer that was created on the surfaces of the samples during aluminizing. The beneficial effect of aluminizing was found to be more evident in the case of Inconel 738LC alloy samples which showed lower oxidation rates at all test temperatures. The results have been discussed on the basis of the differences in aluminum contents of the alloys and their effects on diffusion.