Damage Development Under Cavitation Erosion and Electrochemical Properties of a New Lightweight Multicomponent Mg-10Li-9Al-6Zn-4Si Alloy

A new lightweight multicomponent Mg-10Li-9Al-6Zn-4Si alloy is produced using the disintegrated melt deposition method. Its phase structure, mechanical and electrochemical properties, as well as damage growth under cavitation erosion conditions are investigated. X-ray diffraction reveals alpha-Mg matrix and several intermetallic phases. Microhardness, yield stress, and ultimate compressive strength are higher compared to pure magnesium. The elongation at fracture decreases, remaining at 12%. Electrochemical tests show the alloy to be more noble than pure magnesium. Nevertheless, the corrosion properties in synthetic seawater are typical of magnesium alloys. Cavitation erosion tests are carried out using a cavitating jet device. The aim is to investigate the influence of cavitation erosion and corrosion processes on the growth of defects over time. Short cracks are formed as the tests begin. Nevertheless, despite additional exposures, their growth is effectively blocked by intermetallic phases. The zigzag shape of the short cracks, together with the numerous branches, confirms the fatigue nature of the cavitation erosion phenomenon. Oxidation of the alloy and/or interaction with corrosion processes contribute to very rapid closure of the short cracks. This indicates a good damage tolerance and a good self-healing capacity of the new alloy.