INFLUENCE OF STRUCTURE AND COMPOSITION ON ATOMIC MOBILITY IN NI(AL)-BASED SOLID-SOLUTIONS AND NI3AL-BASED INTERMETALLICS

Atomic mobility was characterized by investigating the isothermal rela xation of short-range order (SRO) in a Ni(Al,Ti) solid solution and of long-range order (LRO) in three intermetallic compounds Ni3Al, Ni-3(A l,Ti) and Ni-3(Al,Ta) by means of residual resistivity measurements. T he relaxation in the intermetallics was much slower than in the solid solutions and in both cases the kinetics were strongly affected by a p artial substitution of Al by Ti or Ta. The application of power law ki netics led to the determination of relaxation time-constants, and in t he solid solutions to the corresponding activation enthalpies for self -diffusion.