Stacking Disorder in Martensites of Cobalt and Its Alloys

Stacking disorder in the h.c.p. martensites of the pure Co, Co-10.2at%Be and Co-19.5at.%Ni alloys has been studied by electron diffraction, utilizing the selected-area diffraction technique of an electron microscope. The shifts of diffraction spots along [00.1] direction due to stacking faults are observed with these martensites. The shifts are analyzed by Kakinoki theory with Reichweites=2, and the corresponding stacking fault probabilities are found to be α=0.03~0.3. It is considered that these stacking faults are introduced due to the constraints imposed by the surrounding matrix crystal.