FP-LAPW investigation of Al₃(Sc1−xTix) alloys properties in L1₂ and D022 structures

Abstract

The ab-initio calculations based on the density functional theory (DFT) have been performed to study the structural, mechanical, electronic, thermal and thermodynamic properties of Al3Sc and Al3Ti binary compounds and their ternary mixture Al3(Sc[Formula: see text]Ti[Formula: see text]) in L12 and D0[Formula: see text] structures. The total energy calculations show that the L12 structure is the more stable one. The Al3Sc[Formula: see text]Ti[Formula: see text] undergoes a martensitic transformation and the formation enthalpies and the lattice parameters decrease with increasing concentration x. The elastic constants are determined and the results show that all compounds are mechanically stable and the cubic cells are more easily deformed by shearing than by unidirectional compression. The elastic modulus indicates that the addition of Ti atoms to Al3Sc improves its ductility. The densities of states (DOSs) calculations show the strong spd hybridization which leads to the formation of a pseudo-gap near the Fermi level in ternary alloys. The densities of states at the Fermi level N(E[Formula: see text]) confirm the phase stability. The quasi-harmonic Debye model is used to predict the thermal properties such as heat capacity, Debye temperature, Grüneisen parameter and thermal expansion coefficient of the considered alloys. The determination of Gibbs free mixing energy at different concentrations has been used to calculate the T–x diagram.

The Effect of Alloying Elements on the Structural Stability, and Mechanical and Electronic Properties of Al3Sc: A First-Principles Study

“…For example, Al 24 Sc 6 Y 2 and Al 24 Sc 6 Li 2 have smaller C 11 values, Al 24 Sc 6 Zr 2 had a similar C 11 value, and Al 24 Sc 6 Ti 2 possessed a larger C 11 value. On the other hand, both Al 24 Sc 7 M and Al 24 Sc 6 M 2 exhibited higher C 12 values (Figure 2b), suggesting that the Poisson effect was enhanced [25]. Additionally, the Al-Sc-M systems had shown a slightly reduced tendency for C 44 (Figure 2c), especially for the Al 24 Sc 6 M 2 , indicating that the resistance to shear deformation was gently diminished.…”

“…Moreover, the effect of transition metals on the structural stability of Al 3 Sc 1-x M x was studied by the special quasi random structures method [23]. In addition, the properties of Al 3 Sc 1− x M x (M=Zr, Ti) with different concentrates, were performed [24,25]. Nevertheless, the influences of the doping elements on the mechanical and electronic properties of the Al-Sc-M system have required further investigations.…”

Effect Mechanism of Sc Addition and T6 Heat Treatment on Precipitated Phase and Mechanical Properties of Al‐Cu‐Mn Alloy

“…This shows 0.3% Sc is a special value for the microstructure and properties of Al-Cu-Mn-xSc alloy. The literatures [32][33][34][35][36] show one of the concentration selection principles of Sc in the Al alloy is to make several Sc enter a supersaturated solid solution during casting and make it form Al 3 Sc precipitate particles dispersed and distributed in an aluminum alloy matrix in subsequent treatment, and at the same time, make a small part of Sc refine its grain by precipitation of Al 3 Sc particles. Al 3 Sc belongs to a cubic structure, and its density of it is 3.03, which disadvantage of using Sc as an alloying element is that its maximum equilibrium solubility is only 0.35%.…”

First-principles study of the mixing effects of rare earth solute atoms on the physical properties of Al2RE phases in Al-based alloys at finite temperatures

“…Based on the above results, we have further calculated the coarsening rate of Al 2 RE particles according to Lifshitz and Slyozov [79] and Wagner [80] (LSW) methods, namely K LSW , which is expressed as [61,81]:…”