Effect of Y on ZL114A eutectic silicon and mechanical properties with gravity casting under different cooling rates

Abstract

The effects of different content of Y element on the morphology, mechanical properties and fracture mode of ZL114A alloy in as-cast and solid-solution-quenched state were studied by SEM and room temperature tensile test under the conditions with different cooling rates. The results show that Y can degrade eutectic Si and improve the mechanical properties of the as-cast alloy under both slow cooling (V=0.16 ℃/s) and fast cooling (V=3.2 ℃/s) while the effect is more obvious under fast cooling. Eutectic Si deteriorated by Y element is more likely to be fusible and spheroid during solid solution treatment. Therefore, the mechanical properties of the alloy in the solid solution quenching state are better and the elongation is greatly improved. With the addition of Y element, the crack initiation mode of ZL114A alloy is changed from being generated at the interface of eutectic Si and aluminum matrix to the combination of fracture of eutectic Si and being generated at the interface of eutectic Si and aluminium matrix.

Keywords

• y
• eutectic silicon
• cooling rate
• mechanical property
• zl114a alloy