Multiscale modification of aluminum alloys with deep cryogenic treatment for advanced properties

Deep cryogenic treatment (DCT) has arisen as a promising green technology to modify the properties of metallic materials. Here we present a substantial (55%) improvement to the wear resistance of an Al-Mg-Si alloy using DCT without any deterioration of other mechanical properties. This improvement is attributed to a slight hardness increase resulting from multiscale microstructural modifications. DCT modifies the morphology of dispersoids as well as the organization and morphology of β'' precipitates that increase their fraction (25%) at the expense of β' precipitates. These effects are related to the greater nanoscale mobility and segregation of the alloying elements (Mg, Si) following DCT, resulting from lattice defect recombination. This research provides a fundamental breakthrough in understanding the DCT effect on aluminum alloys, confirming DCT as a feasible CO2-free treatment step towards improvement of aluminum alloys.