Preparation and characterization of porcupine-fish-spine-inspired AZ91/SiC composites with radial lamellar structures

Abstract

There is a growing demand for lightweight, damage-tolerant, and wear-resistant structural materials, and it is difficult to produce such materials with conventional methods. In this work, we prepared AZ91/SiC composites with a porcupine-fish-spine-inspired structure through radial freeze casting and pressureless infiltration, and investigated the effect of the thermal conductivity of the freezing mold (copper, brass, and stainless steel molds) on the structure and mechanical properties of the composite prepared. Owing to a higher axial-radial temperature gradient ratio, scaffolds prepared with the steel mold had a stronger orientation of ceramic layers, and the corresponding composites had higher flexural strength and fracture toughness compared with those prepared using the copper mold. The main toughening mechanisms were crack deflection and uncracked-ligament bridging. In particular, a radially frozen composite had a lower dry wear rate (by 20%) at cross-sectional surfaces than a conventional axially frozen composite. This paper presents an economical and scalable method for the preparation of high-performance lightweight metal matrix composites.