TY - JOUR

T1 - Evaluation of the glass-forming ability of Nb-Ni-Ti-Zr quaternary alloys using the CALPHAD approach

AU - Tokunaga, Tatsuya

AU - Ohtani, Hiroshi

AU - Hasebe, Mitsuhiro

PY - 2007/7

Y1 - 2007/7

N2 - The glass-forming ability of Nb-Ni-Ti-Zr quaternary alloys has been evaluated by combining the Calculation of Phase Diagrams method with the Davies-Uhlmann kinetic approach. Time-temperature-transformation (TTT) curves were obtained for steady state nucleation for the calculations, which give the time required for the formation of detectable amounts of a crystalline phase from a supercooled liquid as a function of temperature. Then, the critical cooling rates for glass formation were calculated from the TTT curves. Among the input parameters for the calculation of the TTT curves, the driving force for crystallization of the crystalline phase was derived using the thermodynamic function of each phase formulated in previous studies. The calculations show that the critical cooling rates for Nb40-x-yNi60Ti xZry alloys decrease with increasing Zr content up to 20mol%Zr. In particular, the calculated values for the Nb10Ni 60Ti10Zr20 and Nb5Ni 60Ti15Zr20 alloys were around 100 K/S.

AB - The glass-forming ability of Nb-Ni-Ti-Zr quaternary alloys has been evaluated by combining the Calculation of Phase Diagrams method with the Davies-Uhlmann kinetic approach. Time-temperature-transformation (TTT) curves were obtained for steady state nucleation for the calculations, which give the time required for the formation of detectable amounts of a crystalline phase from a supercooled liquid as a function of temperature. Then, the critical cooling rates for glass formation were calculated from the TTT curves. Among the input parameters for the calculation of the TTT curves, the driving force for crystallization of the crystalline phase was derived using the thermodynamic function of each phase formulated in previous studies. The calculations show that the critical cooling rates for Nb40-x-yNi60Ti xZry alloys decrease with increasing Zr content up to 20mol%Zr. In particular, the calculated values for the Nb10Ni 60Ti10Zr20 and Nb5Ni 60Ti15Zr20 alloys were around 100 K/S.

KW - Calculation of phase diagrams (CALPHAD)

KW - Glass-forming ability

KW - Metallic glasses

KW - Niobium-nickel-titanium-zirconium

UR - http://www.scopus.com/inward/record.url?scp=34548026739&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=34548026739&partnerID=8YFLogxK

U2 - 10.2320/matertrans.MJ200736

DO - 10.2320/matertrans.MJ200736

M3 - Article

AN - SCOPUS:34548026739

VL - 48

SP - 1635

EP - 1638

JO - Materials Transactions

JF - Materials Transactions

SN - 1345-9678

IS - 7

ER -