| MB15-RE, which belongs to high strength magnesium alloy, has been widely used in the field of astronavigation. At present, forming technologies of magnesium alloys include die-casting, forging and extrusion, and so on. However, the mechanical properties of magnesium alloy can't be satisfied by means of die casting technology. As for forging and extrusion, they can't satisfy the shape requirement of work piece with complex shape. Semi-solid metal processing is a new net-shape forming technology, in which complex shape close to cast parts and high mechanical properties close to forge piece can be obtained. The arrival of Semi-solid metal forging has established a new way for magnesium alloy work pieces with complex shape. Generally speaking, preparing non-dendritic structure in Semi-solid state and obtaining the best thixotropic process parameters are key factors for Semi-solid metal processing. Based on this, by means of three different kinds MB15-RE magnesium alloy (as-cast,as-ECAEed and as-liquidus forged)prepared by experimental methods, the formation and the character of thixo-structure, mechanical behavior and rheological characteristic of MB15-RE magnesium alloy with high solid fraction have been investigated in this paper.In this study, Semi-solid isothermal heat treatment is employed to prepare the non-dendritic structure in Semi-solid state for three different kinds'billets. In addition, with the help of optical microscope, their partial remelting microstructures are also studied. The results demonstrate that non-dendritic structures in Semi-solid state of three different kinds billets have been obtained; the higher the temperature is or the longer the holding time is, the smoother the boundary of grains turn; in comparison with those of as-cast and as-liquidus forged MB15-RE magnesium alloy, as-ECAEed MB15-RE magnesium alloy can get the smaller and the smoother spheroidized structure.The experiment of Semi-solid state isothermal compression is employed to investigate the mechanical behavior of three kind's billets in semi-solid state with high solid fraction. From the results obtained it can be concluded that the true stress-true strain curves of three states are characterized by three stages, those are... |
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