Desenvolvimento e caracterização de nanocompósitos Al/Nb2O5 processados por high-pressure torsion

Abstract

The transportation industry searches not only for lighter materials, but also for materials that are resistant, in order to reduce fuel consumption and consequently to suits in the environmental regulations. To achieve this demand, new materials have been developed, among them, the metal matrix composites with nanostructured niobium oxide. Aluminum matrix composite material with superior properties to pure aluminum was developed. Samples of pure Al and Al reinforced with nanoparticles (10% wt. of Nb2O5) were produced via powder metallurgy and sintered at 600°C for 1h. In addition, the samples were processed by high-pressure torsion (HPT) for different numbers of revolutions N= 1/8, 1 and 5. The maximum microhardness values presented by samples MMC_HPT_5 and Al_HPT_5 were ~150Hv and 80Hv, respectively. It was observed the coalescence of nanowires of Nb2O5 after sintering and formation of particles with hundreds of nanometers, as well as the formation of Al2O3 and partial aluminothermic reduction of Nb2O5 to NbO2. Processing by HPT promoted the diffusion of Nb to the dislocations in the aluminum grain, acting as a hardening mechanism. The MMC_HPT_5 presented maximum microhardness values very close to the sample processed only by HPT, manufactured by Silva et. al (2019) under the same conditions. Furthermore, in both Al/Nb2O5 samples, it was found that grain refining is not the main hardening mechanism.