Ni-based bulk glassy alloys with large supercooled liquid region exceeding 90Â K

The formations of glassy and supercooled liquid phases in Ni-Nb-Zr-Ti, Ni-Nb-Zr-Ti-Pt and Ni-Nb-Zr-Ti-Pt-Cu alloys were studied by using X-ray diffraction, transmission electron microscopy, differential scanning calorimetry and isothermal calorimetry. It is found that the additions of Pt and Cu increase the supercooled liquid region of Ni-Nb-Zr-Ti alloy from 42 to 89 and 91 K, respectively. The increase in the supercooled liquid region is achieved mostly because Tx rises more intensively than Tg with Pt content. Quite low liquidus temperature of about 1300 K and high Tg value of about 850 K obtained for the studied alloys lead to a high Tg/Tl ratio which reaches 0.65 and favors the glass-forming ability. Nucleation and growth of Ni4Ti3 and Ni10(Zr,Ti)7ss phases takes place from the supercooled liquid in Ni60Nb10Zr15Ti15 and Ni52.5Nb10Zr15Ti15Pt7.5 alloys.