Abstract
The influence of deviation of composition from stoichiometry and of substitutional alloying elements on the strength of the polycrystalline intermetallic compound Ni3Al was investigated by the compression test over the range from room temperature to 1000°C. The main results obtained are as follows.
(1) The shape of the work hardening curve is observed to be linear at room temperature, and it turns out to be a parabolic one at a higher temperature.
(2) The yield stress increases almost linearly with the increase of alloying contents at room temperature, and the solution hardening ratio also increases. The ratio is higher in the order of solutes Cu, Ti, Ni, Ta and Al, successively.
(3) The positive temperature dependence of yield stress is observed from room temperature to about 600°C for all specimens and the temperature where the yield stress attains a maximum value is little changed.
(4) The temperature and composition dependence of yield stress of Ni3Al is more pronounced at the Al-richer side than at the Al-poorer side than stoichiometry.
(5) The variation of yield stress arising from deviations from the stoichiometry and the substitutional solution hardening in Ni3Al cannot be explained only in terms of a decrease of the long range order parameter or by a change of the lattice parameter.
