Study On Directional Solidification Texture And Its Transformation Texture In Pure Iron

As many physical and mechanical properties of polycrystalline materials are highly dependent upon the orientation distribution of the crystallites in the bulk, it is important to understand the evolution of preferred crystallographic orientation, or texture, due to processing conditions. Understanding this is also crucial in optimizing subsequent processing procedures to help predict and improve final product performance. Preferred orientation or crystallographic texture, which strongly influences the anisotropy of material properties, frequently develops as a result of mechanical deformation and thermal heat treatments. It has been made clear by extensively investigations that during directional solidification of many metallic or non-metallic materials and their compounds, a sharp texture occurs through competitive growth of crystals. Owing to different solidification heat parameters and materials crystalline anisotropy in itself, the types of preferred orientation or texture occur variously. Nevertheless, few reports about texture in directional solidification inherited from phase transformation have been come up with. It has to pointed out that transformation texture in directional solidification can be more concisely scrutinized compared to transformation texture in roll processing which always involves either deformation texture or recrystallization texture. Practically, directional solidification processing often served as an important method of manufacture structure materials and functional materials. In these materials, the study of texture in directional solidification for cubic structure materials become concised and keep its common significance.In our study, electrical pure iron directional solidification samples were obtained through method of High Rate Solidification (HRS) and method of Zone Melt Liquid Metal Cooling (ZMLMC). The quality of directional solidification was checked and analyzed by means of macroscopic observation, metallographic analysis and X-Ray diffraction scan. The result showed that the samples obtained by HRS method failed to directionally solidify by withdrawing the mould from the furnace assembly at a speed of 100μms^-1, while the samples of ZMLMC method was successful directionally solidified by withdrawing the ampoule from the furnace at a speed of 15μms^-1. Optical metallographic analysis showed there were lots of column crystals arrayed orderly in solidification direction , in addition,feather feature crystals side-branching from the column crystals were observed. The reason for such results...