Effect of Si distribution on the fracture toughness of A356 aluminum alloys

In the present study the effect of Si distribution of cast A367 aluminum alloy on fracture toughness was investigated through it-situ fracture experiment. For this purpose, three cast processing methods, which were Rheo-casting, and casting-forging, were used to make different microstructure such as Si distribution and alpha dendrite size. The mechanical properties and fracture toughness were investigated in relation with micro-fracture mechanisms. In-situ fracture experiment showed that eutectic Si particles segregated along cells were cracked first while alpha matrix hindered crack propagation. Tensile properties and fracture toughness of the cast-forged sample which microstructure was modified through hot forging process was superior to other two sample alloys because it had more homogeneous eutectic Si.