Modeling of the atomic ordering processes in Fe3Al intermetallics by the monte carlo simulation method combined with electronic theory of alloys

Abstract

The evolution of atomic ordering processes in Fe 3 Al has been modeled by the Monte Carlo (MC) simulation method combined with the electronic theory of alloys in pseudopotential approximation. The magnitude of atomic ordering energies of atomic pairs in the Fe 3 Al system has been calculated by means of electronic theory in pseudopotential approximation up to sixth coordination spheres and subsequently used as input data for MC simulation for more detailed analysis for the first time. The Bragg-Williams long-range order (LRO) and Cowley-Warren short-range order (SRO) parameters have been calculated from the equilibrium configurations attained at the end of MC simulation for each predefined temperature and Al concentration levels, which reveal the evolution of the system from DO 3 → B2 → disordered state as temperature increases. The variation of ordering parameters with temperature has identified the transition temperature from DO 3 → B2 type superlattice, and from B2 → disordered (a) solid solution at about 540 °C and Ͼ900 °C, respectively, showing good qualitative agreement with experimental results. The results of the present study imply that combination of electronic theory of alloys in pseudopotential approximation with MC simulation can be successfully applied for qualitative or semiquantitative analysis of energetical and structural characteristics of atomic ordering processes in Fe 3 Al intermetallics.

Modelling and Monte Carlo simulation of the atomic ordering processes in Ni3Al intermetallics

“…The results of this simulation study showed that such a combination of methods can be successfully applied for qualitative and/or semi-quantitative analysis of energetical and structural characteristics of the atomic ordering processes in Fe 3 Al-type intermetallics. In this present study, therefore, it is of interest to confirm the validity of the approach proposed by Mekhrabov and Akdeniz [5] for the description of the atomic ordering processes in the L1 2 -type ordered intermetallics such as Ni 3 Al.…”

“…In the present study, our intention is not to perform solely MC simulation using a large number of atoms for the complete description of atomic ordering processes; it is rather to confirm the validity of the new approach proposed in our previous study [5] for the evaluation of atomic ordering and order-disorder transition phenomena in Ni 3 Al intermetallics with the L1 2 -type ordered FCC superstructure. A three-dimensional 15 × 15 × 15 lattice with L1 2type unit cell having 13 500 lattice sites has been defined for MC simulation.…”

“…The partial ordering energies of substitutional binary A-B alloys, W αα (R), as a function of interatomic distance, R, with an equilibrium vacancy concentration, c V , can be calculated based on the electronic theory of multicomponent alloys in the pseudopotential approximation, details of which are given in our previous study [5].…”

“…The unique physico-chemical and mechanical properties of aluminides are attributed mainly to the presence of various types of LRO superlattices, SRO states, order-order and/or order-disorder phase transformations occurring in these intermetallics. Recently, a combination of the electronic theory of alloys in the pseudopotential approximation with the Monte Carlo (MC) simulation method has been applied for the analysis of atomic ordering processes and DO3 → B2 → disordered phase transformations in Fe 3 Al intermetallics for the first time [5]. The results of this simulation study showed that such a combination of methods can be successfully applied for qualitative and/or semi-quantitative analysis of energetical and structural characteristics of the atomic ordering processes in Fe 3 Al-type intermetallics.…”

Effect of alloying on the phase stability and elastic properties of L12 Cu3Pt crystal structure

“…On the other hand, ordered intermetallics constitute a unique class of materials that form long-range ordered (LRO) crystal structure below a critical temperature that is generally referred to as the critical order-disorder phase transition temperature [15,16]. The interest in such materials emanate from their attractive properties such as high strength, stiffness, stability and oxidation resistance ideal for structural applications at elevated temperatures [15]. The thermodynamic stability of these compounds relates to their high bond strength brought about by ordering.…”