The Effects of the Secondary-Phase Distribution on the Dissolution Rate and Mechanical Properties of Soluble Al-Mg-Ga-In-Sn Alloys

The relationships between microstructure, dissolution, and mechanical properties of a soluble Al-Mg-Ga-In-Sn alloy are investigated in the present study. The findings demonstrate that the influence of low-melting-point elements on the dissolution of aluminum alloys can be attributed to the formation of secondary phases composed of Mg2Sn and In3Sn at grain boundaries and their participation in the Al–water reaction. After annealing, the secondary phases at grain boundaries transform from point-like and block-like discontinuous particles to strip-like continuous intergranular phases which envelop the Al matrix, resulting in a 29.8% reduction in the volume. These transformations increase the total contact area of the Al–water interface, amplifying the corrosion current of the annealed alloy to more than 30 times that of the as-cast alloy, thereby accelerating the dissolution rate. Unlike magnesium–lithium alloys, the soluble Al-Mg-Ga-In-Sn alloy exhibits a balanced strength, ductility, and dissolution rate, which presents it as a cost-effective, lightweight, structurally and functionally integrated material for the realm of petroleum exploration.