Estudo das propriedades mecânicas e da adesão de compósitos de alumínio reforçados com nanotubos de carbono e processados por Accumulative Roll Bonding (ARB ) e Cross Accumulative Roll Bonding (CARB)

Abstract

Severe plastic deformation techniques, using high levels of plastic deformation, have been commonly used in the refinement of metal grains, mainly with the objective of producing an increase in mechanical strength. Among the techniques used, Accumulative Roll Bonding (ARB) has been shown to be an efficient and low-cost method, which has also been used in the manufacture of Metal Matrix Composites (MMC) of high mechanical strength, involving an immense variety of combinations of base metals and reinforcements, aiming at improvements in mechanical properties, such as an increase in yield stress and in the tensile strength limit, without a marked loss in percentage elongation and toughness. Variations of this method, such as cross accumulating roll bonding (CARB), characterized by the alternating change of the rolling axis as the cycles occur, have been reported in the literature as an evolution of the original technique, since the change in the deformation path tends to provide greater grain refinement. Several studies have also been carried out on the mechanisms by which adhesion between sheets occurs using the mentioned methods. In this context, the present study proposes to investigate the mechanical properties of aluminum Al 1200 H14 metal matrix composites, processed by ARB and CARB, with and without the addition of carbon nanotube (CNT) reinforcements, and, in particular, the adhesion of aluminum Al 1200 H14 metal matrix composites processed by ARB, without the addition of reinforcements. The results obtained by tensile tests indicated a maximum increase of 338.8% and 298.5% in the yield stress and ultimate tensile strength, respectively, for the composites processed by 6 cycles of ARB+CNT, compared to the samples tested in the annealed state. In addition, studies using experimental tests and finite element simulations allowed proposing a complementary interpretation to the film theory, the most widely used model to explain the adhesion mechanisms between laminated sheets.