Dissolution behavior of Mg-Al-Cu and Mg-Zn-Cu alloys for fracturing ball applications: A comparative investigation

As-extruded Mg-6Al-1Zn-0.5Cu and Mg-6Zn-0.5Cu alloys with comparable strength were prepared, and their dissolution behaviors in KCl solutions with different Cl⁻ concentrations were investigated for use as fracturing balls. The results of electrochemical and immersion tests consistently demonstrated that Mg-6Al-1Zn-0.5Cu alloy exhibited superior corrosion resistance across all tested environments. Specifically, in 1 wt.% KCl, it displayed a lower corrosion current density (1.28 × 10^–4 A/cm²) and weight loss (19.2 mg/cm²/d). This superior performance was attributed to its finer grains, smaller galvanic potential differences, and more stable oxide film. Furthermore, a strong dependence on Cl⁻ concentration was established, with higher Cl⁻ levels accelerating corrosion. This research provides insight into the microstructure-corrosion relationship and offers guidance for material selection, recommending Mg-6Al-1Zn-0.5Cu alloy for fracturing balls across a wide range of Cl⁻ environments during the initial stage of hydraulic fracturing.