High-Dissolution Mechanism of Ti-48Al-2Cr-2Nb Alloy in Electrochemical Machining from a Nonlinear Dynamic Perspective

High-rate dissolution process of Ti-48Al-2Cr-2Nb alloy in electrochemical machining exhibits strong nonlinear dynamic characteristics, but the quantitative relationship between these nonlinear characteristics and surface topography, as well as the electro-dissolution mechanism, is unknown. Therefore, the fractal and recursive features of dissolution behavior and quantitative characterization of the dissolved surface topography were investigated. Additionally, an electro-dissolution mechanism model in electrochemical machining process was presented. Applying a higher potential of 11 V can enhance the stability of the electrochemical system, resulting in a smoother and uniform surface. The saturation correlation dimension, surface roughness, and integral area of lacunarity initially decrease before increasing with higher electrolytic pressure, while laminarity and determinism show an initial increase followed by a decrease. These five characteristic parameters reach their optimal values at an electrolyte pressure of 0.4 MPa, indicating that achieving a stable and deterministic electrochemical system is crucial for obtaining a uniform smooth surface. These nonlinear dynamic characteristic parameters can be considered as in-situ monitoring parameters for surface quality in ECM. The anodic dissolution process comprises three stages: initial passive film dissolution and breakdown, rapid dissolving with surface coarsening, and stable dissolving with polishing. The dissolution process of Ti-48Al-2Cr-2Nb alloy is revealed by current density curves, phase space reconstruction, and recurrence plot. The smaller saturation correlation dimension D2 is, and the closer determinism and laminarity approach 1, the more uniform and smoother the micromorphology is. It is attributed to the polishing action of the supersaturated salt layer.image (c) 2024 WILEY-VCH GmbH