Wear and Impact Deformation Behavior of a Centrifugally Cast Multi-reinforced Functionally Graded AA6061 Composite

B4C particles are an excellent reinforcement in functionally graded Al composites (FGCMs) owing to their superior characteristics compared to other widely used ceramic particles. Fabrication of AA6061-6 wt% B4C FGCM was done through K2TiF6 flux-assisted centrifugal casting, resulting in a continuous radial compositional gradient of the ex-situ B4C and in-situ Al3Ti particles. While the concentration of both ex-situ and in-situ reinforcements declined from outer to inner periphery, the finer in-situ particles possessed a more gradual compositional gradient than a steeper gradient for the ex-situ particles. The particle-rich outer region showed 27% and 17% higher hardness and compressive yield strength, respectively, than the particle-free inner zone, stemming from the strengthening effect offered by both the reinforcing agents. The wear property improvement was substantial as the outer region presented 67% and 52% lower CoF and wear loss, respectively, at a load of 5 N. Deformation behavior of the FGCM was characterized using unnotched and notched impact testing. During the impact loading, a higher resistance by the outer region to crack initiation without any notch enhanced the impact energy of the FGCM by 36%. The B4C particle fracture and initial crack extension through more pronounced void formation around the in-situ Al3Ti phases consumed a significant impact energy. However, the crack propagation energy for the outer and inner regions remained similar due to significant secondary crack formation. This work promotes the Al-B4C FGCM, incorporating supplementary in-situ phases, for a feasible material option in many applications requiring component property gradients. © The Author(s) under exclusive licence to The Korean Institute of Metals and Materials 2025.