First-Principles Phase Stability Calculations of Pseudobinary Alloys of (Al,Zn)3Ti with L12, D022, and D023 Structures

Abstract

The thermodynamic and mechanical stabilities of the Al3Ti-Zn3Ti pseudobinary alloy system is investigated from first-principles through density-functional theory calculations within the generalized gradient approximation. Both supercells calculations and sublattice cluster expansion methods are used to demonstrate that the addition of Zn to the Al sublattice of Al3Ti stabilizes the cubic L12 structure relative to the tetragonal DO22 and DO23 structures. This trend can be understood in terms of a simple rigid-band picture in which the addition of Zn modifies the effective number of valence electrons that populate bonding and anti-bonding states. The calculated zero-temperature elastic constants show that the binary end members are mechanically stable in all three ordered phases. These results point to a promising way to cost effectively achieve the stabilization of L12 precipitates in order to favor the formation of a microstructure associated with desirable mechanical properties.

Multicomponent multisublattice alloys, nonconfigurational entropy and other additions to the Alloy Theoretic Automated Toolkit

“…To fix the ideas, refer to Table 1 for an example exploiting all of these extensions. The multicomponent multisublattice features of ATAT have been used, for instance, in [14][15][16]. The remainder of this section introduces the requisite extensions to the cluster expansion formalism.…”

“…Calculate the property tensor associated with each structure. 15 This is highly application-dependent.…”

Study on the Microstructure and Wear Behavior of In-Situ Al3Ti/Al Composites Under Induction Heating

“…However, a new Al3Ti diffraction peak appeared at 58°, which indicated that Al3Ti with the D023 crystal structure appeared in the phase composition [9]. A previous study reported that the Al3Ti with a crystal structure of D023 could be obtained from the transformation of D022 and the unstable state of L12 [10], proving that the crystal structure of Al3Ti was transformed under this parameter. When the current was fixed at 15 A and the frequency was increased to 10 kHz, there were Ti and Al diffraction peaks in the phase curve of the composites, and no other products were found, proving that the Al-Ti reaction did not occur.…”

INTEGRATED COMPUTATIONAL MATERIALS ENGINEERING (ICME) INVESTIGATION OF ELECTRICAL CONDUCTIVITY AND THERMODYNAMIC STABILITY FOR PRECIPITATION STRENGTHENED Al-Zn-Zr AND Al-Zn-Ni TERNARY ALLOYS

“…In order to develop ternary alloys that have improved balance between mechanical and electrical properties, while maintaining a low-cost, Al-Zn-Zr and Al-Zn-Ni alloys were studied. These alloy combinations were selected as promising candidates because of the low impact of Zn, Ni and Zr on electrical conductivity [12,13] and their ability to form desirable coherent precipitate structure (L12) [12,14,15]. According to Hatch, Zn, Ni and Zr rank among the elements with the lowest impact on electrical conductivity when in or out of solution.…”

“…In this study the effect of Zn on the relative stability of L12, D011, D022 and D023 phase structures of Al3TM, Zn3TM and intermediate compositions are examined. For each atomic fraction of Zn in the intermetallic, whichever phase structure has the lowest ∆ , is considered to be the most stable structure for that particular composition [18].…”