In order to obtain information on the temperature dependence of the stacking-fault energy of the matrix in superalloys, hot-stage studies were made of dislocation nodes in Co-Ni-Cr(-Mo) alloys by means of 500kV and 200kV electron microscopy (figure 1). The results revealed that the most important mechanism controlling irreversibility of the shape of the dislocation nodes during thermal cycling depended upon phenomena in which the diffusion of solute atoms took part. The width of extended dislocation nodes was distinctly contracted by heating above about 500C. It was considered that the abnormally extended dislocation nodes observed in quenched specimens were introduced by quenching stress. The Measurement of the Stacking Fault Energy of the Matrix in Superalloys at High Temperature. H.Suto, Y.Tomono: Journal of the Japan Institute of Metals and Materials, 1973, 37[10], 1082-7