A modified embedded-atom potential for L1{sub 0} {gamma}-TiAl

Journal Article · Fri Mar 19 04:00:00 EST 1999 · Scripta Materialia

DOI:https://doi.org/10.1016/S1359-6462(99)00036-6· OSTI ID:352445

Chen, D ^[1]; Yan, M; Liu, Y F ^[1]

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1. Shanghai Jiao Tong Univ. (China). Dept. of Materials Science

Among various empirical or self-empirical methods to date, the embedded atom method (EAM) of Daw and Baskes has been used successfully in a large number of applications. A basic limitation of the EAM is that is spherically averages the electron density which precludes directional bonding. Baskes et al. have modified the EAM to include the angular dependence of the electron density, i.e., the modified embedded atom method (MEAM) potential, and a variety of MEAM potentials for cubic and hcp elements have been developed. The {gamma}-TiAl with L1{sub 0} structure features a high tendency of covalent bonding. In this case, it is crucial to include the directional bonding in the potential configuration. In some attempts to model the L1{sub 0} {gamma}-TiAl using EAM potentials, the results show an incorrect equilibrium state with the lattice constant ratio c/a < 1, whereas experimental results give the value of c/a > 1. The elastic constants also cannot be fit exactly. Therefore, MEAM provides an ideal approach to represent atomic interactions for materials with strong directional bonding features. The basic theoretical framework used in the present study to establish the {gamma}-TiAl MEAM potential is based on the work of Baskes et al. In this work, the second-neighbor interaction has been considered in both the potential fitting procedure and subsequent simulations on bulk and crystal defect properties. Although the nearest-neighbor model was adopted while constituting the potentials by Baskes et al., in the cases of defect structures and surfaces, the second-neighbor interaction was included in their calculations with the introduction of a screening effect.

• Sponsoring Organization: USDOE, Washington, DC (United States)
• OSTI ID: 352445
• Journal Information: Scripta Materialia, Journal Name: Scripta Materialia Journal Issue: 8 Vol. 40; ISSN 1359-6462; ISSN SCMAF7
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CHEMICAL BONDS
CRYSTAL DEFECTS
CRYSTAL MODELS
INTERMETALLIC COMPOUNDS
POTENTIALS
SIMULATION
TITANIUM ALLOYS