Produção e caracterização de ligas Al-(3, 5, 10)Mg-0,1Sc por solidificação direcional e refusão superficial a laser

Abstract

The present study involved the investigation of the Al-3, -5, and -10% Mg-0.1% Sc alloys processed either by Directional Solidification (DS) or Laser Surface Remelting (LSR), as well as correlating the corresponding microstructures with mechanical properties and with solidification cooling rates. Due to the combination of low density, excellent mechanical properties, and adequate corrosion resistance, these alloys can be applied in different sectors such as aerospace, automotive, and microelectronics. Since the microstructure depends on the chemical composition and processing conditions, further studies regarding the solidification of these alloys are necessary. Cooling rate has a direct influence on the microstructural characteristics and phase morphology. Upward directional solidification enabled the analysis of microstructures with different cooling rates. The study of surfaces treated by laser helped deepen the laser treatment of these Al-Mg-Sc alloys, which are highly relevant to the industry currently. The alloys were characterized by optical microscopy, X-ray diffraction, transmission and scanning electron microscopy, tensile properties, and hardness measurements. This study explores complementary solidification techniques, facilitating extensive mapping of microstructures relative to the solidification thermal parameters. Notably, upward directional solidification in Al-Mg-Sc alloys exhibited diverse microstructural features like cells and dendritic morphologies. The Al-5% Mg-0.1% Sc alloy displayed enhanced mechanical strength due to its refined cell microstructure. Laser surface remelting (LSR) enhanced alloy hardness and refined surface microstructure significantly, outperforming directional solidification (DS) by reducing cell spacing in approximately 20 times, thereby increasing Vickers hardness by 15-20% in Al-3% and -5% Mg(-Sc) samples.