The evolution of quasicrystal during additive manufacturing and aging treatment of a Si-modified Al–Mn-Sc alloy

By adding Si to Al-Mn-Sc alloy, an aging strengthened aluminum alloy with stable quasicrystal (QC) phase for additive manufacturing (AM) was developed, in which the QC-Al81Mn19 in as-printed sample transforms to QCAl74Mn20Si6 by the long-range reaction-diffusion of Si atoms (Al81Mn19+Si -> Al74Mn20Si6+Al6Mn) during aging strengthening (holding at 325 degrees C for 4 h), rather than crystallizing into intermetallic compounds. In AM process, the Mn-rich clusters (QC-embryo) nucleate from melt, subsequently, the matrix transforms to QC-phase as follows: matrix -> clusters (nuclei) -> GP-zones -> long-period stacking order -> QC-phase during subsequent solidstate phase transformation of AM thermal cycling.