Effects of SiC_p distribution on microstructure, mechanical properties and deformation behavior of SiC_p/2024Al composites

SiC (p) /2024Al composite was prepared by semi -solid stirring casting , and the distribution of SiC (p) was regulated by multi -step deformation of hot extrusion and multi -direction forging (MDF ). The effects of SiC (p) distribution on the microstructure and properties of SiC (p) /2024Al composite ware studied. The results show that hot extrusion deformation cause SiC (p) to distribute along the extrusion direction (ED ). After multi -directional forging , SiC (p) distribution is improved significantly , and it changes from directional distribution to uniform distribution. After 1MDF , the SiC (p) distribution along the ED changes to disordered distribution , and the mechanical properties of the material are sharply decreased. After 3MDF , the distribution uniformity of SiC p is improved , and the mechanical properties of the material are greatly improved. When the forging passes increase to 6 , the distribution uniformity of SiC (p) is further improved , the mechanical properties of the material decrease with the partial SiC (p) breaking. When the forging number is 3 , the mechanical properties of the composite are optimal , with yield strength , ultimate tensile strength and elongation are 264 MPa , 387 MPa and 7% , respectively. Compared with the directionally distributed composite , the uniform distribution of SiC (p) effectively relieves the local stress concentration , and the matrix alloy stores more dislocation. In addition , when the distribution uniformity of SiC (p) is improved , the Al (2) Cu phase is also refined. The diffuse distribution of Al (2) Cu phase hinders the slip of dislocation , resulting in a uniformly distributed composite with a higher work hardening rate and internal stress. In order to study the effect of SiC (p) distribution on softening behavior of composites , cyclic stress relaxation experiments are carried out. In the process of stress cycling , the uniformly distributed SiC (p) /2024Al composites with uniform distribution of SiC (p) and Al (2) Cu phases exhibit a better stress relaxation resistance.