Fiber pushout and interfacial shear in metal-matrix composites

The mechanical response of a fiber/matrix interface is very important in determining the strength and the fracture behavior of metal-matrix composites. As a means of examining interfacial shear behavior, the use of the "thin-slice" fiber pushout test is becoming increasingly common. However, recent thin-slice pushout tests suggest interfacial failure processes depend not only on intrinsic factors (e.g., interfacial bond strength and toughness and matrix plasticity), but also on extrinsic factors (e.g., specimen configuration, thermally induced residual stresses, and the mechanics associated with the test). In light of these factors, this article briefly describes the contrasts in the mechanics of fiber pullout and fiber pushout. In addition, selected aspects of thin-slice fiber pushout behavior are examined to illustrate the physical nature of the interfacial shear response and its dependence on both intrinsic and extrinsic factors.