Effect of Hot Extrusion on the Microstructure and Corrosion Behavior of Soluble Mg–9Al–1Cu Alloy for Multistage Fracturing

High‐strength Mg–9Al–1Cu alloy is used as a soluble plugging material for multistage fracturing, and the effect of hot extrusion on its corrosion behavior is analyzed. As‐cast (AC) Mg–9Al–1Cu alloy consists of α‐Mg, Mg 17 Al 12 , and MgAlCu phases. After hot extrusion, grains are obviously refined and average size is reduced from 90.67 to 3.75 μm, coarse Mg 17 Al 12 and MgAlCu phases are broken and distributed at grain boundaries, and grain orientation changes from random state to obvious {100} texture. The corrosion forms of both AC and as‐extruded Mg–9Al–1Cu alloys are mainly pitting corrosion, but hot extrusion reduces the corrosion rate attributed to the fine second phases located at the grain boundaries of recrystallized grains and the dense oxide film containing more MgAl 2 O 4 compound.