LASER CLADDING OF Fe-BASED BULK METALLIC GLASSES
Marcos Fernandes de Carvalho1; Piter Gargarella2; Cláudio Shyinti Kiminami1; Conrado Ramos Moreira Afonso1
1 DEMa - UFSCar; 2 DEMa-UFSCar
doi:10.20906/CPS/COB-2015-1854
Resumo
Amorphous overspray powders of Fe72Nb4Si9B15 and Fe43Co29Nb4Si5B19 (at%) bulk metallic glasses (BMG´s) obtained by spray forming were used in order to produce coatings on AISI 1020 mild steel substrate by laser cladding of the pre-placed powders. Several coatings were produced using different power densities (PD-J/mm2) by means of a Yb fiber laser with total power of 2 kW. These coatings were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Vickers microhardness. SEM and XRD analyses of the Fe72Nb4Si9B15 (at%) coating produced with a lower PD (4.0J/mm2) prove its complete amorphous structure due to the high glass-forming ability (GFA) of this alloy and higher cooling rate applied during process. However, the other Fe72Nb4Si9B15 and Fe43Co29Nb4Si5B19 (at%) coatings, irrespective of PD, exhibit nanocrystalline phases with the presence of Fe-α, Fe2B and FeNbB phases, depending on alloy. The coatings showed Vickers microhardness ranging from 340-1180 HV and 822-1260 HV, depending on PD, for Fe72Nb4Si9B15 and Fe43Co29Nb4Si5B19 (at%) coatings, respectively, with higher values obtained for coatings with larger amount of amorphous phase.
Palavras-chave: Laser cladding; Fe-based bulk metallic glass; Amorphous phase; Nanocrystalline coating