Glass-formation and devitrification of the glassy phase in the Ni-Nb-Zr-Ti and Ni-Nb-Zr-Ti-NM (NM, noble metals) system alloys exhibiting the supercooled liquid on heating were investigated. The crystallized structure and kinetics of devitrification of Ni-Nb-Zr-Ti-Pd glassy alloy are studied in detail. The formation of the glassy single phase has been proven using high-resolution transmission electron microscopy (TEM). The addition of Zr and Pd increases the supercooled liquid region of the Ni60Nb25Ti15 (numbers indicate at.%) alloy from 44 K to about 50 K. The cP2 TiNi phase was found to form during the first exothermic phase transformation in all studied alloys. The addition of Zr to Ni-Nb-Ti alloy prevents formation of oP8 Ni3Nb phase observed in the Ni60Nb25Ti15 alloy and initiates formation of the primary Ni10Zr7 phase while the additions of both NM and Zr effectively refine cP2 TiNi particles size. Definite fractions of rhombohedral R and hR14 Ni4Ti3 phases were also observed in NM-bearing alloys. Significantly lower growth rates of the devitrification products in the NM-bearing alloys compared to the Ni-Nb-Ti one may be the reason for the improvement of glass-forming ability (GFA).
|Number of pages||5|
|Journal||Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing|
|Publication status||Published - 2007 Mar 25|
- Glassy alloy
- Nanocrystalline material
- Supercooled liquid