Development of a superb degradable lightweight Mg alloy with high compressive strength

Lightweight Mg alloys with high degradation rates and high strength are attractive for fracturing tools used in unconventional oil/gas extraction. The common design strategy for such alloys is to directly add Ni/Cu into existing high-strength Mg alloys, which meets the high-strength demand but the degradation rates are still insufficient for some extreme downhole environments, especially those with low temperature and low chloride ion concentrations. Here we designed an extruded lightweight Mg-Li-Ni-Cu alloy with superb degradation rate and high strength. The high degradation rate is attributed mainly to the formation of highly effective galvanic couples, Ni/Cu-containing second phases (cathode) and Mg-Li matrix (anode) with ultrahigh potential difference. The degradation rate achieved 2404.3 mm/y, ∼2.3 times higher than the reported highest rate of extruded Mg alloys for fracturing tools. The alloy also has a high compressive strength of 484.9 MPa, which can be attributed largely to grain refinement strengthening.