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The mechanical properties (σb,σ0.2,and δ) and fracture behavior of tensile specimens of the refined A356 alloys were investigated as a function of the addition level of Al-Ti-B master alloy under both as-cast and T6 heat-treated conditions. The results show that as the addition level of Al-5Ti-1B master alloy increases from 0.1 wt.% to 5.0 wt.%,the mechanical properties of refined A356 alloys improve steadily and then decrease slightly under both as-cast and T6 heat-treated conditions. Also,they display excellent mechanical properties with σb = 231.30-258.30 MPa,σ0.2 =134.00-155.50 MPa,and δ = 8.5%-11.75% at T6 heat-treated state. The excellent mechanical properties of refined A356 alloys are ascribed to the formation of α-Al equiaxed dendrites,the improvement of eutectic structure from needle/plate-like to short-lathy/block-shaped,and the Mg2Si aging precipitation phase after T6 heat treatment. The fracture surface examined by SEM exhibits a mixed fracture mode of refined A356 alloys at as-cast state,while it reveals a ductile fracture mode after T6 heat treatment.
The mechanical properties (σb, σ0.2, and δ) and fracture behavior of tensile specimens of the refined A356 alloys were investigated as a function of the addition level of Al-Ti-B master alloy under both as-cast and T6 heat- treated results. The results show that as the addition level of Al-5Ti-1B master alloy increases from 0.1 wt.% to 5.0 wt.%, the mechanical properties of refined A356 alloys improve steadily and then decrease slightly under both as-cast and T6 heat-treated conditions. Also, they display excellent mechanical properties with σb = 231.30-258.30 MPa, σ0.2 = 134.00-155.50 MPa, and δ = 8.5% -11.75% at T6 heat-treated state. The excellent mechanical properties of refined A356 alloys are ascribed to the formation of α-Al equiaxed dendrites, the improvement of eutectic structure from needle / plate-like to short-lathy / block-shaped, and the Mg2Si aging precipitation phase after T6 heat treatment. by SEM exhibits a mixed fracture mode of refined A356 alloys at as-cast state, while it reveals a ductile fracture mode after T6 heat treatment.