Study of engineering developing decagonal-like rational approximant structure of Al–Ni–Cu–Fe–Mn–Cr senary system in aluminum alloy through additive manufacturing

Abstract

Quasi-periodic materials hold unique properties, but mass-producing bulk materials with such structures remains challenging. The rational approximant phase belongs to the Bravais crystal system but exhibits irrational cut features and diffraction symmetries, which are similar to quasicrystals. This study uses additive manufacturing (AM) and prolonged annealing to create an aluminum-based alloy featuring a quasicrystal-like rational approximant phase, Al(Cu, Ni)(Cr, Mn, Fe), overcoming the production limitations of reproducible quasi-periodic materials. This phase transformation occurs at the Al–AlFeNi interface, resulting in a monoclinic periodic structure with long-range translational symmetry. The structure comprises sublattices of stars and compressed hexagons, forming tile mode coverings with pseudo-five-fold decagonal shield-like tiles (SLTs) through transition-element atoms. Furthermore, HAADF imaging reveals clear dark monoclinic rhombic patterns with long-range ordered translational symmetry, free from atomic defects. The rational approximant phase has been verified crystallography through X-ray diffraction, confirming its translational symmetry. Additionally, the Al(Zr, Sc) phase facilitates the phase transformation process through lattice interactions. These findings introduce a novel perspective on the phase transformation in decagonal-like rational approximants and broaden the realm for future engineering applications.