Analysis of interfacial shear strength of SiC fiber reinforced 7075 aluminum composite by pushout microindentation

The interfacial shear strength of continuous silicon carbide fiber reinforced 7075 aluminum matrix composite (SiCf/7075AI) has been investigated in this research by pushout microindentation. The SiCf/7075AI composite specimens were processed by diffusion bonding alternate layers of SiC fibers and 7075AI alloy plates. From the measured stress-displacement curves of indentation tests, the interfacial shear strengths of the composite specimens were obtained, and the stress-displacement curves were basically divided into two regions: (1) elastic deformation and (2) interface decohesion and fiber sliding. With increasing aging time, the interfacial shear strength of the composite increased to 167 MPa for T6-treated specimens, and the variation of the interfacial shear strength well followed that of the ultimate tensile strength of 7075AI matrix alloy. With decreasing specimen thickness, the interfacial shear strength of the composite and the amplitude of stress fluctuation slightly decreased because of the stress relaxation effect near specimen surfaces. Under higher indentation velocities, both the interfacial shear strength and the amplitude of stress fluctuation became smaller.