Ab initio investigation of Ti{sub 2}Al(C,N) solid solutions
- Department of Mechanical Engineering, Texas A and M University, College Station, Texas 77843-3123 (United States) and United States and Materials Science and Engineering Program, Texas A and M University, College Station, Texas 77843-3123 (United States)
M{sub n+1}AX{sub n} phases (M: early transition metal, A: IIIA- or IVA-group element, X: carbon or nitrogen) are layered ternary compounds that possess both metal- and ceramic-like properties with numerous potential applications in bulk and thin film forms, particularly under high-temperature conditions. In this work, we use the cluster expansion formalism to investigate the energetics of C-N interactions across the entire Ti{sub 2}AlC-Ti{sub 2}AlN composition range. It is shown that there is a definite tendency for ordering in the C,N sublattice. However, the molar volume and bulk modulus of the ordered structures found along the Ti{sub 2}AlC-Ti{sub 2}AlN composition range show small deviations from the (linear) rule of mixing, indicating that despite the ordering tendencies, the C-N interactions are not strong and the solution becomes disordered at relatively low temperatures. Random solid solutions of Ti{sub 2}AlC{sub 1-x}N{sub x} are simulated using special quasirandom structures (SQS) with x=0.25, 0.50, and 0.75. The thermodynamic properties of these structures are compared to those of the structures found to belong to the ground state through the cluster expansion approach. It is found that the structural properties of these approximations to random alloys do not deviate significantly from Vegard's law. The trend in the structural parameters of these SQS are found to agree well with available experimental data and the predictions of the bulk modulus suggest a very weak alloying effect--with respect to Vegard's law--on the elastic properties of Ti{sub 2}AlC{sub 1-x}N{sub x}.
- OSTI ID:
- 21596891
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 84, Issue 13; Other Information: DOI: 10.1103/PhysRevB.84.134112; (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOYS
ALUMINIUM COMPOUNDS
APPROXIMATIONS
CARBON
CARBON COMPOUNDS
CERAMICS
CLUSTER EXPANSION
ELASTICITY
GROUND STATES
INTERACTIONS
NITROGEN
NITROGEN COMPOUNDS
SIMULATION
SOLID SOLUTIONS
THERMODYNAMIC PROPERTIES
THIN FILMS
TITANIUM COMPOUNDS
TRANSITION ELEMENTS
VEGARD LAW
CALCULATION METHODS
DISPERSIONS
ELEMENTS
ENERGY LEVELS
FILMS
HOMOGENEOUS MIXTURES
MECHANICAL PROPERTIES
METALS
MIXTURES
NONMETALS
PHYSICAL PROPERTIES
SERIES EXPANSION
SOLUTIONS
TRANSITION ELEMENT COMPOUNDS