**2.2 Dislocation**

ECAP [3] and cryo-cross-rolling (CCR) process [4, 5] were carried out on Al 5083 and Al 1050 alloys, respectively. These two processes form a matrix with highly dislocation density, which changes the diffraction pattern. Besides, SAED patterns

**11**

**Figure 2.**

*Transmission Electron Microscopy of Nanomaterials DOI: http://dx.doi.org/10.5772/intechopen.92212*

in **Figure 2**.

cations [3].

**2.3 Kikuchi patterns**

of two alloys demonstrate streaks effects on spots pattern owing to highly pile-up of dislocations. Consequently, incomplete sectors of the rings in patterns were formed owing to preferred orientation in the crystal structure. Spots in the SAED pattern vary from a common shape to points with short and long tails. TEM images of nanostructured alloys and corresponding SAEDPs of the two samples demonstrated

Kikuchi pattern consists of spots and paired parallel dark and bright lines. The spacing between a paired parallel dark and bright-line and the angle between Kikuchi lines in the pattern specify crystal structure characteristics such as the set of reflecting planes and distance of paired lines. By enhancing the thickness of the sample, the spots become more visible and the Kikuchi lines become less visible. Kikuchi patterns usually include spots and Kikuchi lines. Generally, Kikuchi patterns represent much more data rather than the spot patterns about crystal structure. The appearance of obvious Kikuchi pattern expresses a symptom of the ideal crystal. **Figure 3** displays the Kikuchi pattern of γFe with structural specifi-

**Figure 4(a)** illustrates TEM image of nanostructured Al 7075 alloy under thermomechanical processing. Tilting processing of the sample in TEM was applied to investigate the crystal lattice defects and orientation relationships. The SAED pattern includes the Kikuchi lines and spots of Al 7075 alloy was shown in **Figure 4(b)**.

*(a) TEM images and (b) corresponding SAEDP of Al 5083 alloy under ECAP process [3], (c) TEM images and* 

*(d) corresponding SAEDP of Al 1050 alloy under CCR process [4, 5].*

**Figure 1.** *(a) TEM image and (b) SAED of Al 2024 alloy under ECAP process [3].* *Transmission Electron Microscopy of Nanomaterials DOI: http://dx.doi.org/10.5772/intechopen.92212*

of two alloys demonstrate streaks effects on spots pattern owing to highly pile-up of dislocations. Consequently, incomplete sectors of the rings in patterns were formed owing to preferred orientation in the crystal structure. Spots in the SAED pattern vary from a common shape to points with short and long tails. TEM images of nanostructured alloys and corresponding SAEDPs of the two samples demonstrated in **Figure 2**.
