Abstract
his report deals with the effect of additional elements such as Mo, Al, W, V and Nb on the precipitation, and with the behavior of the precipitation due to the heat-treatment in the Ni-base heat-resisting alloys.
The precipitates were isolated electrolytically from specimens, and chemical composition and crystalline structure of the isolated precipitates were determined by chemical analysis and X-ray diffraction, and the shape of the precipitates were observed by electron microscopy. The results obtained were as follows:
(1) The precipitates of aging-treated specimens which were added with several elements consisted of Ni3 (Al·Ti), M23C6 and Ti (C·EN) usually, and the most portion of the precipitates was Ni3 (Al·ETi).
Among the added elements, especially, in the case of Al or Nb addition, Ni3 (Al·ETi) or Nb4 (C·EN)3 was precipitated plentifully, and the amount of precipitates, as-aged hardness and strength at high temperature of the alloys were increased conspicuously.
(2) The insoluble precipitates in solution-treated states were only Ti (C·EN).
The amount of precipitates were influenced by aging temperature, but the effect of solutiontreatment temperature were hardly observed.
The amount of precipitates was increased with the rise of aging temperature, and it showed the highest value when the specimens were aged at 800°C, but precipitates were decreased rapidly in the specimens by aging treatment at above 850°C
Presumably, it should be the result of precipitation or dissolution of Ni3 (Al·ETi) due to the degree of aging temperature.
