Electron microscopical investigation of the structure of metallic films during heating

Conclusions

• 1. A new technique for the direct heating of thin metallic objects in the electron microscope to temperatures of 850–900°C has been developed and used in investigations. The possibility has been established of studying gradual changes in the structure and phases of thin metallic foils during continuous heating, which may prove to be extremely useful in researches into the synthesis of new powder metallurgy materials and also into external friction of metals.

• 2. An account is given of the main structural changes occurring during the continuous heating of pure copper, nickel, and iron; these changes must be allowed for in investigations of phase transformations that may take place in compounds based on these metals.

• 3. It has been established that the recrystallization processes observed during heating in vapordeposited-nickel films correspond with the parallel processes occurring in the same temperature range in foils electrolytically reduced in thickness and annealed outside the electron microscope.

• 4. A characteristic phase (Fe₃C) formation phenomenon was detected during the heating of iron. It appears to be closely linked with the reaction of iron with oil-vapor decomposition products in the heating space.