Influence of micro B₄C ceramic particles addition on mechanical and wear behavior of aerospace grade Al-Li alloy composites

Aluminum matrix composites are being widely used in aircrafts due to high strength to weight ratio, good tribological properties and better castability. The B₄C particles have low density, high hardness, high strength and stiffness. The poor wettability is major challenge during the fabrication of Al-B₄C composite. To overcome this problem, titanium based flux (K₂TiF₆) was used to improve the wettability. In this study, structurally efficient Al-Li 8090 alloy containing 2, 5 and 10 wt% of B₄C particles were fabricated by using modified stir casting technique with an objective to obtain homogenous dispersion of B₄C particles in the matrix. The microstructures evaluation was done to know the distribution of particulates in the matrix. The influence of particle volume content on the mechanical and wear behavior of composites has been investigated. The ultimate tensile strength, micro and macro hardness, high temperature hardness and wear characteristics have been investigated. Ageing behavior, XRD analysis and fractography of the composites has also been studied. The outcome of the experimental investigation revealed that, 2% B₄C particulate reinforced composite exhibits better mechanical, physical and tribological properties. 10% B₄C particulate reinforced composite shows clustering and agglomeration at some local regions causing a drop in the properties. (author)