In order to investigate sub-rapid solidification behavior of semi-solid magnesium alloy metal, a novel semi-solid processing technique, called new vacuum suction casting (NVSC), is used to manufacture thin castings of AZ91D Mg-alloy directly from a liquid metal. The resulting microstructures of castings are characterized in detail and linked to the solidification behavior. In the microstructure of the sub-rapidly solidified SSM sheet, the “preexisting” primary solid particles, with the morphology of near-globules or rosettes, disperse in the homogeneous matrix consisting of fine near-equiaxed secondary α-Mg grains and fine precipitates of β-Mg17Al12 intermetallics. Owing to rapid solidification rate, the volume fraction of the β phase in the sub-rapidly solidified SSM sheets is much lower than that in the as-cast ingot. In addition, the content of alloying elements of Al and Zn was higher in the grain boundaries and the eutectic structure than that in the primary solid particles and in the second α-grains.

The FEM (finite element method) simulation was used to study the diffusion bonding deformation of high purity tungsten target. The influence of different welding structure, bonding temperature on the deformation of the final high-purity tungsten target was systematically studied. Meanwhile, some microscopic properties of tungsten target were developed, such as internal stress size and distributions, strain size and distributions. Finally, physical experiments are used to verify numerical simulation results. The results show that the method of adding an intermediate layer can release the residual stress between the high-purity target and back plate. The bonding stress of high-purity tungsten target is mainly concentrated with the tungsten target and the intermediate layer in between, which is easy to fail during the later leveling process. Small deformation of bonding tungsten target can be obtained by low diffusion bonding temperature.