Explosive anisotropic grain growth of delta-NiMo by solid-state diffusion
- 10 June 1991
- journal article
- Published by AIP Publishing in Applied Physics Letters
- Vol. 58 (23) , 2642-2644
- https://doi.org/10.1063/1.104794
Abstract
Anomalous, anisotropic grain growth has been observed in delta(δ)-NiMo intermetallic compound during the annealings of Mo/Ni thin-film diffusion couples at 700 and 800 °C. Two layered microstructures showing median-sized, equiaxed grains and large columnar single crystalline grains were generated. The growth direction of the columnar grains was parallel to the direction of Ni diffusion flux. Electron diffraction indicated that both the median-sized and the columnar grains were δ-NiMo. The composition of δ-NiMo was determined to be Ni48-Mo52 (at.%). According to the thickness of reaction-formed δ-NiMo, the apparent interdiffusion coefficient was measured to be about 10−10 cm2/s which is 4 to 5 orders of magnitude greater than literature data. The enhanced diffusion rate in Ni-Mo, and the anomalous anisotropic grain growth of δ-NiMo compound are discussed on the basis of exothermic reactions between Ni and Mo during diffusional intermixing. The enthalpy of the formation of δ-NiMo is calculated and demonstrated to be sufficient to cause melting/solidification of the compound.Keywords
This publication has 4 references indexed in Scilit:
- Self-propagating explosive reactions in Al/Ni multilayer thin filmsApplied Physics Letters, 1990
- Explosive silicidation in nickel/amorphous-silicon multilayer thin filmsJournal of Applied Physics, 1990
- Diffusion in the MoNi, MoFe and MoCo slstemsActa Metallurgica, 1974
- X-ray diffraction studies of the δ phase, Mo–NiActa Crystallographica, 1960