摘要
The effect of Ca addition on the solidification microstructure of hypoeutectic Al-Si casting alloys was investigated using scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) methods with particular attention focused on the change of morphologies of primary α-Al and eutectic silicon. Meanwhile,solute distribution in solid-liquid was simulated according to Scheil-Gulliver law. Results showed that primary α-Al and eutectic silicon were refined as Ca content increased because of the variation of the solute concentration in liquid. The addition of Ca increased the nucleation sites like Al3Ti or Al2Cu to promote the nucleation of primary α-Al. Affected by modification effect of Ca, the shape of eutectic silicon changed from flake to fibrous structure. In addition, coarse plate Ca-rich phases could be found along the grain boundary with high Ca content.
The effect of Ca addition on the solidification microstructure of hypoeutectic Al-Si casting alloys was investigated using scanning electron microscopy（SEM） and differential scanning calorimetry（DSC） methods with particular attention focused on the change of morphologies of primary α-Al and eutectic silicon. Meanwhile,solute distribution in solid-liquid was simulated according to Scheil-Gulliver law. Results showed that primary α-Al and eutectic silicon were refined as Ca content increased because of the variation of the solute concentration in liquid. The addition of Ca increased the nucleation sites like Al3Ti or Al2 Cu to promote the nucleation of primary α-Al. Affected by modification effect of Ca,the shape of eutectic silicon changed from flake to fibrous structure. In addition,coarse plate Ca-rich phases could be found along the grain boundary with high Ca content.
基金
financially supported by the National Natural Science Foundation of China(Grant No.51775297)
the National Science and the Tsinghua University Initiative Scientific Research Program(20151080370)
the UK Royal Academy of Engineering/Royal Society through the Newton International Fellowship Scheme
