EFFECT OF STRAIN-RATE ON LOW-CYCLE FATIGUE BEHAVIOR AND MECHANISM OF SICP LY12 COMPOSITE/

A study has been made of the behaviour and fracture mechanism of SiCp/ Ly12 composite in low-cycle impact fatigue (LCIF). The results showed that in LCIF in conditions of lower strain range-higher fatigue life, a cyclic stability: even cyclic softening, happened in the composite. In the LCIF test the fatigue life of the SiCp/Ly12 composite was sensi tive to the content of SiC particles so the LCIF test is an almost uni que method to distinguish small differences in ductility among these b rittle materials. As the composite fractured first in the SiC particle s a break, smash or interface separation occurred, then in the matrix a cavities coalescence fracture was induced. Finally it is seen that u nder many circumstances the SIC particles were really a weakening phas e while increasing the rigidity of the composite, therefore when the c omposite is used as a structural material great attention must be paid to its behavior. (C) 1997 Elsevier Science S.A.