The influence of repeated γ⇆α-transformations on the structure of iron-nickel alloys

Conclusions

• 1. The formation of continuous Debye lines on x-ray diffraction patterns from reversed austenite of 50N25 and N31 alloys single crystalline in the original condition which have undergone repeated γ⇆α-transformations and their absence on microelectron diffraction patterns is caused by the different localization of the two diffraction methods. The recorded differences in the diffraction patterns are related to the different quantities of fragments of the structure in the different volumes of the material.

• 2. Repeated thermal cycling treatment of alloys with γ⇆α-transformations led to gradual replacement of the dislocation mechanism of relaxation of internal stresses by the deformation twinning mechanism, which was caused by the increasing level of internal stresses and the interrelationship between the rules of formation of the structures of austenite and martensite.

• 3. In the actual carbon-free iron-nickel alloy N31 the process of twinning of the reversed austenite developed more intensely than in 50N25 alloy as the result of the more complete transformation.