Herein, a coupled model of temperature field and dendrite growth is built to examine the solidification microstructure of Cr17 stainless steel under vibration. The temperature field is calculated with ANSYS FLUENT software. In addition, considering solute diffusion and local curvature, a low grid anisotropic cellular automaton (CA) model is used to simulate the dendrite growth. To verify the major source of crystal nucleus in the melts, a mechanical model of dendrite fracture is built, and an investigation is conducted on the critical condition of grain dissociation. As indicated from the results, the dendrites are stripped and dissociated into the melt when the vibration frequency and amplitude values exceed the critical condition of dendrite fracture, the grains are dissociated more easily, and the more equiaxed grains are indicated in the melt with the increase in the vibration frequency. It is preliminarily demonstrated that vibration can facilitate the dendrites to break and be dissociated from the chilling generator surface. The simulation results comply with the experiment.

The applications of magnesium alloys are limited because of their poor corrosion properties. In this study, the corrosion behaviours of Mg-3.4Y-3.6Sm-2.6Zn-0.8Zr alloy in 3.5 wt-% NaCl solution were investigated, the results suggested that the precipitations of rare-earth phase, (Mg, Zn) 3 (Y, Sm) and Mg 12 (Y, Sm) Zn, are beneficial to enhance the anti-corrosion of magnesium alloys. The network second phase, (Mg, Zn) 3 (Y, Sm), may act as an anode. It can form a galvanic couple with the adjacent α-Mg matrix and effectively protect the α-Mg matrix. The existence of the Mg 12 (Y, Sm) Zn phase makes the distribution of the (Mg, Zn) 3 (Y, Sm) phase more uniform, which may produce a more uniform electrochemical structure and reduce the galvanic corrosion. Under the dual action of the two second phases, the corrosion performance of Mg-3.4Y-3.6Sm-2.6Zn-0.8Zr alloy was better than that of the standard AZ31B alloy. The corrosion mechanism of the alloy is galvanic corrosion due to the second phase with low potential.