Microstructure and mechanical properties of rheo squeeze casting magnesium alloy

Mg Nd Zn alloys have been widely used in automobile, aerospace and national defense industries due to their excellent comprehensive mechanical properties. In addition, because of its good biocompatibility, the alloys have broad application prospects in the field of biomedical materials.

At present, the main forming methods of Mg nd Zn alloys are metal mold casting and low pressure sand mold casting. However, due to the existence of unavoidable porosity and shrinkage in the metal mold casting, it is not easy to form complex thin-walled castings; while the low-pressure sand mold casting has large grain size, relatively low performance and low production efficiency. The results show that rheo squeeze casting can not only reduce or even eliminate the porosity in the casting, but also refine the grain size significantly. Therefore, it is expected to prepare mg nd Zn magnesium alloy with excellent properties by this process, and broaden the application scope of rheo squeeze casting technology.

Electromagnetic stirring is a common method to prepare semi-solid slurry. Although different researchers have discussed the formation mechanism of non dendritic primary phase under electromagnetic stirring, the evolution process of primary phase has not been observed, especially for the microstructure evolution and formation mechanism of primary phase of magnesium rare earth alloy slurry under electromagnetic stirring. In addition, there are few studies on the effect of weak magnetic field on the thermodynamics of alloy melt, and there are no reports on the specific effects of electromagnetic stirring process parameters on the thermodynamics of slurry and melt temperature, which are very important for the regulation of semi-solid structure of alloy. Furthermore, the rheological behavior of the slurry and the nucleation behavior of the semi-solid mg Zn Alloy during squeeze casting are greatly affected. In addition, the addition of trace y element is beneficial to improve the high temperature properties of Mg nd Zn alloy. The mechanical properties of Mg nd Zn alloy can be further improved by adding trace y element, further optimizing the composition of the alloy and subsequent rheo squeeze casting.

Therefore, it is planned to study the above problems in order to prepare mg nd Zn magnesium alloys with excellent properties and provide theoretical and technical support for obtaining high-quality mg nd Zn magnesium alloy parts. In addition, this paper presents a new technology for preparing and forming mg RE alloy materials, which has certain universality in principle, so it has important reference value for other alloy materials.