Controllable manipulation of crystallinity and morphology of aluminium surfaces using high intensity ultrasound

High intensity ultrasound (HIUS) provides highly non-equilibrium condition for metal processing. Controllable manipulation of crystallinity and morphology of metal coatings is important for different applications including catalysis and corrosion protection. Investigation of effects of HIUS in different sonication media on microstructure and morphology of aluminium (Al) layers showed that HIUS can cause melting and recrystallization of Al. Due to high cooling rate the grain size of Al can be reduced. Ultrasonically induced structure refinement could potentially be used for enhancement of mechanical properties of coatings. If ultrasonically generated temperature is not high enough for metal melting, temperature induced atomic diffusion leads to grain growth, segregation and fragmentation of Al layers and, thus, the formation of attractive for catalytic application increased surface area.