Abstract:The stacking fault probability of CoNi alloys with different contents of Ni was measured by X-ray diffraction methods. The results show that the stacking fault decreases with increasing Ni content and with increasing temperature. The thermodynamical calculation has found an equation that can express the stacking fault energy γof CoNi at temperature T . The phase equilibrium temperature depends on the composition of the certain alloy. The relationship between stacking fault energy γand stacking fault probability P_sf  is determined.

Key words: stacking fault energy； stacking fault probability； martensitic transformation； CoNi alloy