*4.2. Texture Strengthening*

As reported by many researches [26,48], texture also greatly influences the strength and ductility of the Mg alloys. As revealed in the XRD patterns of the alloys, the - 1010 , - 1011 , and - 1120 peaks of the ECAPed alloys were strengthened. Meanwhile, the strongest diffraction peak of the basal plane (0002) was detected. Thus, one can infer that the texture may play an important role in the mechanical property of the processed Mg-9Li alloy. The XRD texture of the E8 and E8R alloys are presented in Figure 8. Due to the cumulative effect of shear stress during the ECAP deformation, the basal texture of the α-rich Mg phase is 40–60◦ with the ECAP-extrusion direction, and the maximum texture density is up to 6.1. Prismatic texture - 1010 and conical texture - 1011 and - 1120 are found with weak texture density. Generally, during plastic deformation of magnesium alloys, the slip in the direction of the basal plane is the first thing to occur [16]. Due to the addition of Li, the ratio of c/a crystal axis is decreased, which is favorable to the dislocation slip in the cylindrical and conical directions. In conjunction with the orientation distribution function (ODF) diagram in Figure 8b, it is found that it is not only the basal plane, prismatic, and cone textures that appear in the α-Mg phase but also there exists (1120) <1100> textures. The texture shows that the local grains were ordered after ECAP processing since the grains in different directions are arranged differently by shear force after multi-pass ECAP processing. These multi-directionally ordered textures block the slip of the grains, leading to an increase in the strength. Figure 8c depicts the pole figures for the {0002} plane of the α-Mg phase, a strong basal texture along the rolling direction can be seen, and it is the appearance of this texture that leads to the significant increase in strength of the E8R alloy. The distribution of the 1010 prismatic weak structure in the rolling direction is 15◦. The 1011 , 1120 conical planes have no particularly apparent texture.

**Figure 8.** XRD texture analysis of the α-Mg phase of Mg-9Li alloys. (**a**,**b**) are polar diagram and ODF diagram of the E8 alloy, respectively; (**c**,**d**) are polar diagram and ODF diagram of the E8R alloy, respectively.
