31. Grain boundaries are generally only a few nanometers wide.32. This decrease in net chemical potential will decrease the grain boundary velocity and therefore grain growth. 33. In order to minimize the effect on properties, grain boundaries are aligned parallel to the dendrites. 34. During grain boundary migration, the rate determining step depends on the angle between two adjacent grains. 35. This reduces the total area of grain boundary and hence the stored energy in the material. 36. Manganese sulfide inclusions have a higher melting point and do not concentrate at the grain boundaries . 37. In a two-dimensional isotropic material the grain boundary tension would be the same for the grains. 38. Selective leaching often involves grain boundary depletion mechanisms. 39. Densification is only achieved at temperatures above 1800 �C once grain boundary diffusion mechanisms become active. 40. These include recombination at defects and grain boundaries .
