1.School of New Energy and Materials，Southwest Petroleum University，Chengdu 610500，China；
2.Chengdu Institute of Advanced Metal Materials Industrial Technology，Chengdu 610305,China
Abstract：Magnesium alloy has become the most promising bone implant and vascular stent materials due to its
good biocompatibility, matched elastic modulus and biodegradability. However, the poor degradation performance
and unclear metabolic mechanism of degradation products limit its further application. In order to meet the degradation
adaptation of magnesium alloy, a novel powder metallurgy named semi-solid powder moulding was adopted to
prepare the medical Mg-6Zn alloy. Semi-solid powder moulding is a near-net shape forming technique, which combines
powder forming and semi-solid forming with one step. It has great advantages to prepare the alloys and its
composites with low melting point and wide solidification range. In order to optimize the forming process and get
excellent performance of Mg alloys, it is necessary to simulate the forming process in the preparation of medical
Mg-6Zn alloy. As this technique simultaneously involves in deformation, solidification and densification, it has
many difficulties in the simulation of forming process. This study gives a clue for the simulation of semi-solid powder
moulding based on the Shima-Oyane model. At beginning, the constitutive equation of Mg-6Zn powder materials
was deduced and improved based on the semi-solid compression experiments. The materials constants of Mg-
6Zn powder materials were obtained. This study simulated the semi-solid compression process of Mg-6Zn powder
materials by MSC. Marc software. The relative density and displacement of powders were simulated and was
proved by the experiments. The influence of forming temperature on the semi-solid powder moulding process was
studied. The results show that the forming temperature has little effect on the relative density when the liquid fraction is less than 10%, and the relative density gradually increases and tends to be stable with the progress of compression.
The stress of semi-solid powder moulding is concentrated at both ends of the edge of the cylindrical
blank. The minimum stress locates in the "belly" area at both ends of the center and the edge of the cylindrical
blank. The experimental results agree well with the simulated results. With the increase of liquid fraction higher
than 10%, The difference between the simulated and experimental results are becoming larger and larger. This model
has good reliability when the low liquid fraction is lower than 10%. However, the error is large with high liquid
fraction. The liquid is the main factor making this error. A new model suitable for semi-solid powder molding
needs to be established urgently.
2022, Vol. 32 
