Surface morphology and electrochemical behaviour of Ti-48Al-2Cr-2Nb alloy in low-concentration salt solution

Abstract

Electrochemical machining (ECM) is becoming increasingly important for the efficient machining of parts with a large machining area. This is an addition challenge for ECM because of the very high machining current. To overcome this difficulty, a direct and effective strategy is to adopt the machining mode that uses a low-concentration electrolyte with a low current density. The purpose of this study is to reveal the electrochemical behaviour and surface morphology in low-concentration electrolyte. The polarization behavior of Ti-48Al-2Cr-2Nb is measured by linear sweep voltammetry and cyclic voltammetry curves. The ηω-j curves demonstrate the special dissolution behaviour of Ti-48Al-2Cr-2Nb at low current densities. The surface morphology, surface quality, and dissolution mechanism are analysed in three low-concentration electrolytes at different current densities after the ECM dissolution experiments. The results demonstrate that Ti-48Al-2Cr-2Nb exhibits three unique dissolution morphologies in the three solutions, and we found that the γ-TiAl phase dissolves faster than the α2-Ti3Al phase. These results also show that 1% NaCl solution is more suitable for Ti-48Al-2Cr-2Nb in ECM compared with the other two solutions, considering its good surface quality, low breakdown potential, and high material removal rate. Later, the dissolution process of the sample in 1% NaCl solution at different corrosion times is revealed. Moreover, a dissolution model is proposed for the electrochemical dissolution behaviour of Ti-48Al-2Cr-2Nb in 1% NaCl solution.

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Correspondence to ZhengYang Xu.

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This work was supported by the National Natural Science Foundation of China (Grant No. 91960204), the Natural Science Foundation for Distinguished Young Scholars of Jiangsu Province (Grant No. BK20170031), and the Fundamental Research Funds for the Central Universities (Grant No. NE2014104).

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Wang, Y., Xu, Z., Zhang, A. et al. Surface morphology and electrochemical behaviour of Ti-48Al-2Cr-2Nb alloy in low-concentration salt solution. Sci. China Technol. Sci. 64, 283–296 (2021). https://doi.org/10.1007/s11431-019-1558-8

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Keywords

  • electrochemical machining
  • γ-TiAl alloy
  • low-concentration salt solution
  • surface morphology
  • electrochemical behaviour