金属における界面制御

-粒界偏析の制御による金属材料の性能向上-

抄録

The properties of metallic materials can be improved by controlling the grain boundary segregation of solutes. Basic problems in the segregation control are discussed : addition of the third elemennt can decrease the segregation of harmful impurities and increase that of beneficial solutes. As an example, the effect of carbon on the segregation of phosphorus in iron is discussed. Carbon and phosphorus are considered to compete with each other at the site at grain boundaries. Since carbon has a larger segregation energy than phosphorus, it preferentially segregates to decrease the segregation of phosphorus. With this effect and with its own effect to increase the grain boundary cohesion in iron, carbon prevents the intergranular fracture in steels. Other effects of solute-solute interaction on their segregation are discussed in principle.