Abstract
The Ni3Al intermetallic alloys with the composition of Ni-25mol%Al were produced by powder metallurgical method using elemental powders of nickel and aluminum. After blending starting powders, sintering was performed by hot press process. Some sintered alloys were heat treated for homogenization. Influence of the microstructural change caused by the heat treatment on the mechanical properties for compacts was investigated. Although the mean grain diameter of as-sintered alloys was about 32μm, finer microstructures with the diameter of less than 7μm were achieved by homogenization heat treatment, Alloys were found to be composed of single Ni3Al phase and the degree of long range order increased with homogenization time. As-hot pressed alloy revealed the flow stress at room temperature of about 300MPa, whereas the homogenized alloy showed that of about 700MPa. Flow stress was analyzed by decomposing it to σG, σH and σp, which were the stress components concerning Peierls force, positive temperature dependence of flow stress, and grain diameter respectively. The Hall Petch parameter, ky, was about 1.3 at room temperature and had the tendency to decrease with temperature.
