A Numerical Study of Microporosity Formation in the Al-4.1%Cu Binary Alloy during Solidification
M. Xiong and A.V. Kuznetsov
This paper presents numerical investigation of microporosity formation in solidification of a binary Al-4.1%Cu alloy. This investigation is based on a novel three-phase model of the mushy zone, which assumes that the mushy zone consists of the solid, liquid, and gas phases. Microporosity formation model is based on the thermodynamic approach, which assumes that the pore nucleates when the excess pressure (which is the difference between thermodynamic pressure of the dissolved gas in the interdendritic liquid and the local pressure at the same location in the mushy zone) becomes sufficiently large to overcome the surface tension (providing the gas bubble has a radius that is small enough to fit into the interdendritic space). Special attention is given to the investigation of the effect of microporosity formation on the inverse segregation. Numerical results are compared with published experimental data. The factors that affect the solute redistribution and microporosity formation are investigated.