Microstructural investigations of the PM superalloy N18 in deformed and undeformed state.

In the present work microstructural investigations by means of transmission electron microscopy (TEM) were carried out on the powder metallurgy (PM), nickel-base superalloy N18. The material was characterized in the as-received, hot extruded state as well as after complete heat treatment. Especially the gamma-distribution and the presence of further precipitates were considered. The elemental distribution was characterized with the assistance of energy dispersive X-ray analysis (EDX) and energy filtering (TEM) (EFTEM). Additionally strain rate controlled tensile tests with different strain rates were carried out at 700 degrees centigrade in laboratory air. The microstructure of the deformed material was mainly investigated on dislocation distribution and deformation inhomogeneities.