The researchers studied a high-strength aluminum alloy called Al-5.5Zn-2.5Mg. They looked at its structure using different microscopes and tested its strength and fatigue properties. The alloy showed good mechanical strength and fatigue resistance. It had a tensile strength of 479.4 MPa and could withstand 630 cycles of fatigue at certain conditions. The alloy had tiny strengthening particles evenly spread out and mostly located at grain boundaries. These particles were about 20 nm in diameter. The fatigue cracks started on the surface of the material and showed distinct patterns as they grew.