定向凝固(Directional Solidification)又称定向结晶,是金属或合金由液态转变成固态时,晶粒按控制的方向生长的一种工艺。对于一个具体铸件(如涡轮叶片)而言,定向与非定向的区别在于前者是由许多平行排列的柱状晶构成,而后者是由无数等轴晶构成的(图1)。因此,定向材料的晶界基本上被控制成与铸件应力轴相平行,而非定向却是不规则 Directional Solidification (Directional Solidification), also known as directional crystallization, is a process in which grains or alloys grow in a controlled direction when a metal or alloy changes from a liquid state to a solid state. For a specific castings (such as turbine blades), the orientation and non-orientation difference is that the former is composed of many parallel columnar crystals, while the latter is composed of numerous equiaxed crystals (Figure 1). Therefore, the grain boundaries of the oriented material are essentially controlled parallel to the stress axis of the casting, whereas the non-oriented but irregular