Grain Boundary Engineering and Development of Materials

초록

With the advance of nano-technology, grain boundary engineering (GBE) emerges as a new methodology for enhancing the limit of conventional materials. GBE is based on the spatial distribution of grains in terms of the morphology as well as the grain orientations, collectively referred to as the grain boundary character distribution (GBCD). Enhancement of the creep resistance, crack resistance and corrosion resistance has been reported separately or in combination in some commercial Ni-base alloy, Pb-base alloy and an intermetallic compound by adjusting the fraction of coincident site lattice (CSL) boundaries. A successful GBE requires both high-powered experimental analytical tool and computer modeling such as electron back scattered diffraction (EBSD) method and Monte-Carlo simulation of microstructure. Monte-Carlo simulation of microstructural development has been applied to the systems including WC, Fe-Si alloy and Zr. Initial computer microstructures were generated by either from the microscopic EBSD data or by discretizing statistical XRD data. Movement of grain boundaries with differential mobility could be simulated by assigning arbitrary mobility for special boundaries or by a continuous energy-dependent variation of the mobility. The result showed that the existing theories of texture development could be erroneous in predicting the microstructure in Fe-Si alloy.