Micromechanical Behavior Of A Cu-Ag Lamellar Composite Processed By Cold Rolling

The mechanical properties of polycrystalline metals are mainly depended on the internal micro-structural characteristics,especially in terms of the slip systems that operate during plastic flow and the orientations of each grain.Therein texture plays an important role in adjusting the properties of materials,directly influencing the properties in production and engineering application.Hence,it is important to understand the microscopic deformation mechanism and predict deformation texture for research and exploitation of new materials,and which has been a significant development direction in materials' fields.In this paper,the characteristics are examined by X-ray diffraction(XRD)and a Crystal Plasticity Finite Element(CPFE)model is employed to study the texture evolution mechanism for the biphasic fcc metal lamellar composite interaction between the copper and silver with different stacking fault energy(SFE).Analyzed by the XRD texture determination,results indicate that cooper with medium SFE presences significant inhomogeneous texture distribution in different thickness.In fact,there is an increase in the strength of ?-fiber and ?-fiber texture with increase in deformation,and the grains are rotated to both Copper orientation and Brass orientation in B-Cu and J-Cu.Copper-type and Brass-type texture component were equivalent with the deformation reduction less than 80%in the J-Cu,while it continues until to the 93%in the B-Cu.When the reduction gets to 93%,the intensity of Brass component is larger than that of the Copper component.And in the B-Cu,the Copper component is the main texture orientation at the 98%reduction.In the silver,the a-fiber texture decreases with the increasing of reduction after 80%while the ?-fiber texture is completely opposite.The results showed that,grain rotation of the internal copper layer of lamellar composite is significantly affected by the abutting silver layer and the hetero-phase interface.Shear banding becomes the dominant deformation mechanism of Cu layer,and plays a serious role in the stages of the development of the Brass component.On the other hand,CPFE constitutive model that incorporates dislocation,twinning and shear band systems is applied to simulate rolling texture of bicrystal fcc metal with different SFE and hetero-phase interface in this paper.It is confirmed that the shear band development in an individual crystal is strongly related to the initial orientation of crystal and also to the mechanical properties and orientation of its abutting crystals.Copper-oriented crystal shows the stronger tendency to form shear bands than the Goss-oriented crystal.Cu with medium stacking fault energy is much harder to initiate shear banding than Ag with low stacking fault energy.In the case of the hetero-phase interface,the deformation of the bicrystal model produces a significant shear effect on each other,and the grains then rotate to the Brass-R and Rotated-Cube orientation.According to the study of bicrystal model with different initial orientation,shear banding is the main cause of the texture evolution in the largest grain rotation.In the sample of single-phase Cu and diphasic polycrystal,when the reduction gets to 60%,the intensities of Brass component were lager than Copper component comparing the texture evolution of single-phase Cu.The shear banding becomes the dominant deformation mechanism.