In the previous study (Tetsu-to-Hagané, Vol.44, 1960, No.4, pp.487-492) the authors reported the effect of Mo, W, V and Nb on properties of heat-resisting 38% Ni alloy. In the present paper, the effect of Al, Al+Ti and W+V+Nb on the hardness as solution-treated and aged, mechanical properties at room temperature and high temperature, rupture strength, oxidation resistance and resultant microstructures were examined.
At the same time, precipitates therein were isolated by electrolysis so as to examine the quality and the form of them.
The results obtained were as follows:
(1) With the alloy containing 0.7-2.32%Al, as the Al was increased, hardness after solution treatment, aging hardness, tensile strength at room temperature and high temperature, rupture strength and oxidation resistance were increased, while the elongation, reduction of area and Charpy impact value were decreased.
(2) As concerns the effect of Al+Ti, the hardness and strength at high temperature were increased. However, the toughness was decreased as the Ti content was increased, when the sum of Al and Ti was constant. The effect of Ti, therefore, was more sensitive than that of Al.
(3) With respect to the influence of W+V+Nb, Nb was most effective, when the alloy contained Nb together with W and V; and by increasing the Nb content, the strength at high temperature was improved. When the V was compared with W, addition of V was better than that of W for raising the strength at high temperature.