Enhanced Mechanical and Degradation Properties of Hollow Glass Microspheres/Mg Matrix Composites by Incorporating Copper Power for Degradable Downhole Tool Applications

In this work, the effects of Cu addition on the microstructure, mechanical properties, and degradation behavior of the hollow glass microspheres/Mg alloy composites (HGM/MA) are investigated. The results indicate that with the Cu content increases from 0 to 2 wt.%, the grain size reduce from 17.89 ± 1.15 to 12.05 ± 0.85 μm, the compressive strength and Brinell hardness increase from 303 ± 5.5 MPa and 87.2 ± 2.5 HB to 381 ± 9.2 MPa and 119.8 ± 3.3 HB, increase by 25.7% and 37.4%, respectively. When the Cu content is less than 1 wt.%, the formed fine and dispersive Al₂CuMg phase provides more galvanic‐corrosion sites, and promotes the exfoliation of the corrosion product layer during degradation process, thereby accelerating the degradation rate. While the excessive Cu addition (>1.5 wt.%) results in the formation of net‐like Al₂CuMg phase, which can act as a corrosion barrier to hinder the further degradation of the composites. The composites with 3 wt.% Cu exhibits the highest degradation rate of 88.65 mg cm⁻² h⁻¹ in 3 wt.% KCl solution at 366 K, with a favorable ultimate compressive strength of 352 MPa, which is thought as an ideal candidate material for the degradable downhole tools.