Ice-nucleation properties of aluminum surfaces

The nucleation of ice from supercooled water droplets plays a critical role across various technological sectors including aviation, power transmission, shipping and space flight. Despite its importance, the fundamental mechanisms of water freezing on surfaces remain poorly understood. In this study, we investigate the freezing behavior of supercooled droplets on several aluminum alloys (1050, 5083, 5251, 6060 and 6082) using our custom-designed IceBox instrument. Our findings show that all aluminum surfaces exhibit moderate ice-nucleating capabilities. High levels of surface oxidation and magnesium content lead to higher average ice-nucleation temperatures, and rough surfaces generally promote ice formation more effectively than polished ones. An exception is the freshly polished 1050 alloy, the softest and purest aluminum examined, where micrometer-scale “pit” features appear to initiate ice nucleation. After surface aging, the 5251 alloy displays the highest ice-nucleating ability, while the 6082 alloy shows the lowest. Overall, our results highlight the importance of considering the interplay between surface roughness, specific defects and alloy composition when aiming to reduce ice formation on aluminum surfaces.