COMPARATIVE STUDY ON DEFORMATION CHARACTERISTICS OF AL SINGLE CRYSTAL UNDER DYNAMIC AND QUASI-STATIC COMPRESSION

Meng Jiahong，Li Shukui，Liu Jinxu，Ma Siming

ABSTRACT: The aluminum single crystal with face-centered cubic (FCC) structure was subjected to quasi-static and dynamic uniaxial compressive loading along the direction, respectively. The surface appearance, morphology and orientation of the loaded samples were analyzed. The experimental results showed that the deformation mechanisms of single crystal aluminum were both dislocations under quasi-static and dynamic loading, and the samples underwent non-uniform plastic deformation from single crystal to polycrystal. The causes of the nonuniform plastic deformation are as follows: the two sets of slip systems actuated by single-crystal aluminum under quasi-static loading have obvious sequential order and different slip amount; the material deforms rapidly under dynamic loading, and the distribution of slip band has obvious local concentration. The microstructure evolution of the aluminum single crystal into polycrystal is as follows: First, the thick strip-shaped deformation structure is formed by the dislocation slip, and as the deformation amount increases, the quasi-static sample forms a subgrain boundary by the internal dislocation accumulation, while the dynamic sample forms a subgrain boundary by dislocation rotation. Then, the unstable subgrain boundary is gradually transformed into a low angle grain boundary during the deformation process, later forming a high angle grain boundary.

Keywords: Single crystal aluminum, dynamic and quasi-static, slip band, dislocation