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THERMODYNAMIC AND KINETIC ANALYSES OF FORMATION OF AMORPHOUS AND NANOCRYSTALLINE ALLOYS WITH THE AID OF COMPUTER AND DATABASE

A. Takeuchi1,* , A. Inoue1

Affiliation

  1. Institute for Materials Research, Tohoku University, Sendai 980-8577 Japan

Abstract

Thermodynamic and kinetic simulations were performed to clarify the formations of amorphous and nanocrystalline alloys On the basis of the Miedema’s model partially assisted by a database, the amorphous-forming composition region (AFCR) and crystallization temperature (Tx) of the multicomponent amorphous alloys were calculated from thermodynamic approaches. On the other hand, kinetic simulations were performed for Ni-Nb binary eutectic system by the phase field model. The AFCRs calculated for ternary alloy systems containing practically important elements such as Al, Cu, Fe, Ni, Ti agree with the experimental trends. The values of Tx for iron-group-based alloys are calculated with approximate errors of several tens of Kelvin to the experimental data. For Ni62.4Nb37.6 alloy, the critical cooling rate (Rc) for formation of amorphous phase and incubation time (t) for crystallization are calculated to be Rc= 3·102 K/s and t=1000 s. These values are closed to the value calculated from the time-transformation diagram for crystallization based on the homogeneous nucleation theory (Rc=1.4·103 K/s t=105 s). The present study indicates the importance of the simultaneous analyses of transformations from thermodynamic and kinetic aspects for the development of amorphous alloys in near future..

Keywords

Thermodynamics, Kinetics, Amorphous alloy, Nanocrystalline alloy, Database.

Submitted at: April 26, 2004
Accepted at: June 10, 2004

Citation

A. Takeuchi, A. Inoue, THERMODYNAMIC AND KINETIC ANALYSES OF FORMATION OF AMORPHOUS AND NANOCRYSTALLINE ALLOYS WITH THE AID OF COMPUTER AND DATABASE, Journal of Optoelectronics and Advanced Materials Vol. 6, Iss. 2, pp. 533-540 (2004)