Study on the Precipitation in Ni-Al Alloy Aged under Applied Tensile Stress

Abstract

The effect of applied tensile stress during aging on Ni₃Al precipitates in Ni-Al alloy (7.49 wt%Al) which is the fundamental system of Ni-base heat resisting alloys, was studied by means of measurements of the electrical resistance, electron microscope observations and the tensile testing. The results obtained were as follows: (1) The larger the applied tensile stress during aging (400°∼700°C), the more the precipitation of Ni₃Al was promoted. (2) Ni₃Al precipitated along the same crystal orientation of the matrix, regardless of whether the tensile stress was applied or not during aging. (3) The yield and tensile strength of the specimen aged at 600°C under 2 kg/mm² tensile stress were higher than that of the specimen aged at the same temperature under no stress, and the elongation to fracture of the former was smaller than that of the latter.