21 - Fiber-reinforced metal-matrix composites

Abstract

This chapter focuses on the impact of using ceramic nanofibers as a reinforcement to enhance mechanical properties of metal matrix composites. Metal matrices like Al and Mg were selected whereas ceramic and carbon nanofibers were used as the reinforcement fibers. These fibers were fabricated using an electrospinning method, and heat induction sintering to perform the consolidation process of the metal-matrix composites. However, to improve the mechanical properties (like strength, hardness and elastics modulus) of the composites, the percentage of reinforcement needs to be optimized. High-frequency induction heat sintering (HFIHS), on the other hand, is an exclusive and effective method that sinters ceramics and metallic nano-powders to almost theoretical densities. Attributable to the strong interfacial conformity between the fibers and the metal matrix, the application of ceramic nanofibers to light metal matrices plainly showed enhanced stability and this led to a better composite's mechanical properties as well as high compressive strength and durability. This could be associated with the homogeneous nanofiber dispersion in nano-scale metal matrix. Furthermore, the mechanical properties of such metal-matrix composites can be moderated by regulating the volume fraction of the utilized nanofibers. On the other hand, addition of CNFs to the metal matrix, particularly with higher concentrations i.e. >1% depleted the strength of the composite. Such behavior would be due to weakening of crack bridging effect of the CNFs or weak interfacial bonding between CNFs-Al/Mg composite.