EFFECTS OF PROTON IRRADIATION ON THE MICROSTRUCTURAL AND MICROCHEMICAL EVOLUTION OF INCONEL-600 ALLOY

Inconel alloy 600 specimens were irradiated with 1 MeV protons at 450 degrees C to doses of 0.05, 0.5, and 5.0 dpa, at the 4 mu m depth, to study the irradiation effect on the microstructural and microchemical evolutions of this alloy. Two types of specimens with different heat treatments were examined; namely, mill-annealed (MA) and solution-annealed and sensitized (SAS). Before irradiation, the microstructure of the mill-annealed specimen consists of small grains (similar to 20 mu m), uniform dislocations and randomly distributed M(7)C(3) carbides. Irradition enhanced the recovery dislocation structure. M(7)C(3) carbides were the major precipitates and observed along grain boundary and in the matrix. The precipitate morphology coarsened slightly with irradiation dose. The void swelling increased with irradiation dose. At 5 dpa, the total swelling was about 0.3%. Before irradiation, the microstructure of the SAS specimens consisted of large grains (similar to 70 mu m), very low dislocation density (similar to 3x10(13) m(-2)), and semicontinuous M(7)C(3) precipitates along grain boundary. Irradiation enhanced reprecipitation of the M(23)C(6) precipitates in the matrix. Dislocation density increased with increasing irradiation dose due to dislocation loop formation and growth. Grain size, however, kept unchanged during irradiation. The chromium depletion profile was altered by irradiation to more depletion.