# Deformation Behaviour of Cold-Rolled Ni/CNT Nanocomposites
## 3 Results and Discussion  
### Microstructural Characterization of Sintered Samples  
The initial characterization of the samples was carried out to assess whether the reinforcement has any influence on the crystallographic orientation of the matrix during production, as this is a factor that certainly influences the evolution of the texture during  
Figure 1: Schematic representation of (**a**) the cold-rolling equipment and cold-rolled samples and (**b**) the observed sample section, represented by the letter A; \(h_{0}\) and \(h\) represent the initial and rolled sample thickness, respectively; \(\epsilon\) represents the logarithmic strains corresponding to each thickness reduction. plastic deformation. Figure 2 shows the IPF maps, the [111] pole figures, and the inverse pole figures for the Ni matrix and Ni/CNT composite after sintering. Based on these figures, the samples are not characterized by having a marked texture. The introduction of reinforcement changes the crystallographic orientation of the matrix. This can be seen in the pole figures and inverse pole figures of the two samples, shown in Figure 2b,d. For instance, the IPF figures reveal that the Ni matrix has a preferential orientation of directions <111> and <212> parallel to ND, while nanocomposites show a preferential orientation of directions <101> parallel to ND. The IPF of transversal direction (TD) exhibits differences between matrix and nanocomposites. The matrix shows a higher intensity in  
Figure 2: (**a,c**) Inverse pole figures (IPF) maps, (**b,d**) [111] pole figures (PF) and IPF, for the Ni matrix (**a,b**) and the Ni/CNT samples (**c,d**), after sintering. the direction <001> parallel to TD, while the nanocomposite has its preferential orientation divided into two, around <112> and <012>, with lower intensity. Another visible difference is that in Ni, there is a preferential orientation to the direction <101> parallel to the RD. In contrast, in the Ni/CNT, despite <101> also having some intensity, the principal orientation is observed in <111> parallel to RD. The respective PF of the samples illustrates these differences between the two samples. The texture difference can be related to the fact that the presence of CNTs alters the grain rotation during sintering and, in addition, affects the movement and rearrangement of dislocations originating during the dispersion/mixture process, which directly influences the extension of recovery and recrystallization occurring during the sintering of samples, as reported in previous works [3,22]. Several authors have already used the grain boundary misorientation angle to study the deformation of metallic materials [13,31,32,33]. In that sense, a study of the grain boundaries' character and misorientation was also carried out in the as-sintered samples to understand to what extent the reinforcement can influence these important parameters to be evaluated when the samples are subjected to plastic deformation. The maps with the different types of grain boundaries and the distribution of grain boundary misorientation, referring to the Ni and Ni/CNTs samples before deformation, are presented in Figure 3.  
Figure 3: (**a,c**) EBSD maps showing the different boundary types, (**b,d**) grain boundary misorientations distribution of Ni sample (**a,b**) and Ni/CNT sample (**c,d**). This type of analysis was used by [PERSON] et al. [13] in the study of deformed nickel, and by [PERSON] et al. [33], and is common when investigating deformation studies in detail since it allows us to understand the consequences and extension of deformation, for example, through the LAGB fraction, associated with dislocation cells, and the misorientation consequence of this deformation. Although, as mentioned, this analysis is more common on deformed samples, the present work performs it also on sintered samples. This allows investigating the effect of the cold-rolling process, since it characterizes the initial stage (as-sintered).