Solidification behavior of Al particles embedded in an Ni aluminide matrix
- Univ. of Oxford (United Kingdom)
- Chong Ju Univ. (Korea, Republic of). Dept. of Physics
A hypereutectic Al-40 wt% Ni alloy has been manufactured by melt spinning, and the resulting microstructure examined by transmission electron microscopy. As-melt spun hypereutectic Al-40 wt% Ni consists of an Ni aluminide matrix and an Al-rich phase distributed in the form of particles with sizes {approximately} 50--100 nm, and as an irregular layer at the cell and grain boundaries. Diffraction analysis of the Ni aluminide matrix is consistent with the ASTM x-ray diffraction standard 2{theta} values for the orthorhombic NiAl{sub 3} phase, a = 6.6114 {angstrom}, b = 7.3662 {angstrom} and c = 4.8112 {angstrom}. The solidification nucleation kinetics of Al-rich particles have been examined by heating and cooling experiments in a differential scanning calorimeter over a range of heating and cooling rates. Solidification of the Al-rich phase at the cell and grain boundaries nucleates catalytically on the surrounding Ni aluminide matrix at an undercooling of {approximately} 3 K. Analysis of the solidification nucleation kinetics of the Al-rich phase in Al-40 wt% Ni supports the hypothesis that the classical spherical cap model of heterogeneous nucleation breaks down at low undercoolings and small contact angles.
- Sponsoring Organization:
- United Kingdom Engineering and Physical Sciences Research Council (United Kingdom)
- OSTI ID:
- 479243
- Report Number(s):
- CONF-951155--; ISBN 1-55899-301-0
- Country of Publication:
- United States
- Language:
- English
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