CREEP-BEHAVIOR AND DAMAGE MECHANISMS OF SIC-FIBER-REINFORCED TITANIUMMATRIX COMPOSITE

The flexural creep behavior and damage mechanisms of the unnotched SCS -6 fiber-reinforced Ti-6242 matrix composite was investigated at tempe ratures between 550 and 700-degrees-C and stresses ranging from 700 to 1300 MPa. Microstructural observation revealed that multiple fiber br eakage, microcracking along the reaction zone-matrix interface and mat rix cracking, extending from the broken fiber ends, were the major dam age mechanisms during quasi-steady state creep. The stress dependence of the quasi-steady state creep rate indicates that the stress exponen t increased with temperature. The creep behavior of the notched compos ite was also studied at initial applied stress intensity factors K(i) ranging from 15 to 35 MPa m1/2. Muliple fiber breakage, multiple matri x cracking and significant interfacial debonding and/or cracking were observed in the notch tip damage zone.