Obtaining and characterizing multilayer sheets of dissimilar copper alloys by accumulative roll bonding

Abstract

Heterostructured Materials (HM) represent a promising field in the materials and metallurgy domain, despite facing various challenges that need to be overcome. The main question, "How to control microstructural heterogeneities to optimize mechanical properties in HM?" persists as a partially resolved challenge, requiring intensive efforts in both experimental and theoretical. These microstructural heterogeneities encompass grain size gradients and/or chemical composition, lamellar structures, multilayers, hierarchical features, among other denominations and variations. In this context, this project aims to advance in the development and study of lamellar HM, produced by combining two dissimilar alloys with different stacking fault energies (SFE) and, consequently, different mechanical behavior. The microstructural design principle of this lamellar HM is based on the combination in the solid state of two copper alloys, one with an SFE of 78 mJ/m² (Cu) and a brass (Cu15Zn) with 20 mJ/m², exhibiting deformation dominated by dislocation slip and deformation by mechanical twinning (with the effect of twinning-induced plasticity - TWIP), respectively. Thus, by producing multilayered sheets using the accumulative roll bonding (ARB) process, it is expected that thin and alternating layers of both materials result in a synergistic effect of properties, which may even exceed the rule of mixtures. The planned experiments for the 12-month period of this project include obtaining multilayered sheets under different layer thickness conditions, along with proper microstructural characterization (metallography and electron microscopy) and mechanical behavior analysis (hardness measurements and tensile tests with varying temperature and strain rate), enabling the assessment of the outcome of this combination, both in terms of TWIP effect modeling and in determining processing parameters.