Icosahedral phase formation by laser surface remelting of a decagonal-based Al-Cu-Fe-Cr alloy

The Al-Cu-Fe-Cr is one of the most studied QC-forming systems, especially regarding phase formation and in applications as wear resistant coatings. The laser surface remelting process modifies the local microstructure and can improve the mechanical and tribological properties of engineering materials without altering the composition of the bulk material. In this work, the influence of laser surface remelting on the microstructure and mechanical properties of an Al85Cu6Fe3Cr6 (%at) spray-formed alloy, originally consisting of decagonal quasicrystals embedded in an Al-FCC matrix, was studied. Different combinations of laser power, table displacement speed and laser beam diameter were used to produce six different single laser tracks that were then classified according to their morphology and suitability for the surface treatment of this material. Then, a detailed microstructural characterization was performed in a selected laser track, using scanning electron microscopy and transmission electron microscopy while its mechanical properties were assessed by dynamic ultra microhardness. The surface remelted material presented a microstructure with refined icosahedral quasicrystals in the Al-FCC matrix, including Al2Cu particles in quasicrystal/Al-FCC interfaces, while the substrate presented coarse decagonal quasicrystals in the Al-FCC matrix. The laser remelted material presented an increase in the microhardness value compared to the substrate, from 207 to 250 kgf/mm2.