焼結タングステン細線におけるインターロック組織の最適化

抄録

The measurement of the three-dimensional shape of secondary recrystallized grains, and delamination, creep and tensile tests are made to clarify the optimum interlocking grain structure which fills such two opposing roles as the improvement of creep resistance and the prevention of grain boundary fracture in P/M tungsten fine wires. Some parameters characteristic of the degree of interlocking among grains are derived and reliably reflect a distinctive change in the contours of grains which are three-dimensionally constructed. The effect of grain configuration to suppress creep rates with an increase in the degree of interlocking is detected in the structure which has a small area of grain boundary. However, the increase in creep rate is confirmed in the structure which has a large area of grain boundary because of an additional interlocking. On the other hand, the tensile strength increases monotonically at room temperature as the grains are interlocked. It is therefore possible to decide the optimum structure which realizes both high tensile strength and high creep resistance at the same time.