Flow stress measurements were made on γ′-L1
2 ordered Ni
3(Al, Ti) single crystals containing fine dispersion of disordered γ particles over the temperature range of 77 to 1273 K. Slip systems were determined by two-surface trace analysis. Deformation induced dislocations were also observed by transmission electron microscopy (TEM). Tilt experiments by the weak-beam method were made to obtain some information concerning the cross slip mechanism of the superlattice dislocation. The following conclusions were obtained by comparing the mechanical behavior of γ′-Ni
3(Al, Ti) containing γ precipitates with that of γ′-Ni
3(Al, Ti) single phase.
(1) The strength of γ′-Ni
3(Al, Ti) increases over the temperature range of experiment by the precipitation of fine γ particles. The peak temperature where a maximum strength was obtained shifted to higher temperature.
(2) Over the whole temperature range, the interaction between dislocation and γ precipitates is attractive. On the temperature range of 773 to 973 K, the dislocations in γ′ matrix move on (111) primary slip plane. When the applied stress is removed, the dislocations make cross slip into (010) plane, while those in γ precipitates remain on the (111) primary slip plane.
(3) The increase of high temperature strength in γ′-Ni
3(Al, Ti) containing γ precipitates is due to the restraint of cross slip of dislocations from (111) to (010) by the dispersion of disordered γ particles.
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