Kinetics of defect recovery and long-range ordering in Ni{sub 3}Al + B. 2: Atomic jump processes studied by order-order relaxation experiments
- Univ. Wien (Austria). Inst. fuer Festkoerperphysik
Fine isothermal relaxations of the degree of long-range order (LRO) in the homogeneous intermetallic compound Ni{sub 76}Al{sub 24} + 0.19 at.% B (400 wt. ppm) were examined by means of residual resistometry. It was found that two parallel relaxation processes are involved in the phenomenon. The processes dramatically differed in the relaxation rates, but showed close activation energies exceeding 4 eV. A model explaining the occurrence of two parallel relaxation processes and based on the vacancy thermodynamics in L1{sub 2} superstructure is proposed. The evaluated high activation energy for LRO kinetics is attributed to specific modes of vacancy diffusion involving jumps between different sublattices. It is compared with the activation energies of diffusion in Ni{sub 3}Al exhibited by several ternary elements occupying the sublattice of Al. In these terms, the inadequacy of relating Ni diffusion data to the parameters of LRO kinetics in Ni{sub 3}Al is indicated.
- OSTI ID:
- 230795
- Journal Information:
- Acta Materialia, Vol. 44, Issue 4; Other Information: PBD: Apr 1996
- Country of Publication:
- United States
- Language:
- English
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