Mechanical response of boron carbide-aluminum composites during compressiveloading

摘要

The compressive stress-strain and failure behavior of 80'XOBQC-A1 and 65'XOB4C-A1composites has been examined at room temperature and at strain rates of 10-4and 103 s-1. The composite structure has been processed to consist of dual continuous phases such that the B4C and the aluminum are mutually constrained by their physical proximity. Being nearly incompressible, the aluminum supports the BIC skeleton by limiting bending in the B4C ligaments, while the B4C constrains shear in the aluminum and inhibits its plastic flow. Thus, owing to the mutual constraint of the constituents, the compressive fracture strength of the composite is more than a factor of two greater than that of the B4C skeleton with fracture stresses in excess of 2000 MPa in the 65DG/0 B4C-AI and greater than 3800 MPa in the 80DG/0 B4C-AI. The characteristics of the compressive stress-strain response as well as the ratios of transverse strains to longitudinal strains (i.e. the 'Poisson' ratios) indicate that failure of the 65% BIC-A1 composite is controlled by the Al, but that the 80DG/0 B4C-AI is dominated by the B4C.