Effect of TiB2 and Al3Ti on the microstructure, mechanical properties and fracture behaviour of near eutectic Al-12.6Si alloy

A near eutectic Al-12.6 Si alloy was developed with 0.0 wt%, 2.0 wt%, 4.0 wt%, and 6.0 wt% Al-5 Ti-1 B master alloy. The microstructural morphology, hardness, tensile strength, elongation, and fracture behaviour of the alloys were studied. The unmodified Al-12.6 Si alloy has an irregular needle and plate-like eutectic silicon(E) and coarse polygonal primary silicon(P) particles in the matrix-like α-Al phase.The P, E, and α-Al morphology and volume fraction were changed due to the addition of the Al-5 Ti-1 B master alloy. The hardness, UTS,and elongation improved due to the microstructural modification. Nano-sized in-situ AlTi particles and ex-situ TiBparticles caused the microstructural modification. The fracture images of the developed alloys exhibit a ductile and brittle mode of fracture at the same time. The Al-5 Ti-1 B modified alloys have a more ductile mode of fracture and more dimples compared to the unmodified alloy.