Three-dimensional Characterization Of Grain Boundaries And Study On Grain Boundary Wetting Behaviors In Fe-6wt.%Si Alloy

Grain boundary wetting normally exists at the intersection of grain boundary and solid-liquid interface, which is a popular physical-chemical phenomenon occurring during preparing and processing of polycrystalline materials. It is an important mechanism about grain boundary embrittlement and intergranular corrosion caused by the liquid metal phase. Research on grain boundary wetting is of great scientific significance for the preparation of advanced materials and the control of grain boundary embritlement and intergranular corrosion.In the present investigation, Fe-6wt.%Si alloys are prepared with vertical Bridgman method, several grain boundary of Fe-6wt.%Si alloys is characterized by mean of3D reconstruction technique in which way samples with a grain boundary of48°are obtained. In order to reveal internal mechanism of grain boundary wetting, the grain boundary wetting by Zn-rich melt for with48°grain boundary directional solidification in different conditions(different annealing temperature, different annealing time and different magnetic intensity) is investigated by means of microstructure characterization and local composition analysis methods such as SEM and EPMA. The following conclusions can be obtained:1. Annealing at different temperature, the contact angles of grain boundary decrease with increasing of annealing temperature. Wetting phase transition is observed during penetration of zinc alone the48°grain boundary in Fe-6wt.%Si alloy at Tc=740±5℃. The depth of grain boundary grooves below the wetting phase transition temperature changes very little, while the temperature exceeds the grain boundary wetting phase transition temperature.2. Annealing in different time, the contact angles of grain boundary decrease with increasing of annealing temperature, but the decreasing trend is easing. As well as the contact angles are greater than zero annealing in different time, which is known as typical partial wetting characteristic. The depth of grain boundary grooves gradually deepens with the prolongation of annealing time and annealing time follow l=31.97t1/53. When annealing at720℃, after applying magnetic field, the contact angles of grain boundary increase significantly. The magnetic field intensity has no significant effect on the depth of grain boundary grooves.4. For the samples annealed at720℃, magnetic fields promote the diffusion of Zn in the grain boundary including along and perpendicular to the grain boundary, however facilitation Weaken with increase of the magnetic field intensity...