The Measurement of the Stacking Fault Energy of the Matrix in Superalloys at High Temperature

It is well known that the stacking fault energy is one of the most important strengthening factors affecting the high temperature strength of FCC metals and alloys. In this paper, in order to obtain some knowledge of the temperature dependence of the stacking fault energy of the matrix in superalloys, the hot-stage studies of dislocation nodes in Fe-Cr-Ni and Co-Ni-Cr(-Mo) alloys were carried out by means of 500 kV and 200 kV electron microscopes. The results obtained are as follows: (1) The most important mechanism controlling the irreversibility of the shape of dislocation nodes during thermal cycling was considered to depend on some phenomena in which the diffusion of solute atoms took part. (2) The width of extended dislocation node was distinctly contracted by heating over about 500°C. (3) It is considered that the abnormally extended dislocation nodes observed in quenched specimens are introduced by quenching stress.