First-principles investigation of 3d transition elements in L1 TiAl

Abstract

Articles you may be interested in Transition-metal and metalloid substitutions in L10-ordered FeNiThe effect of 3d transition elements ͑such as V, Cr, Mn, Fe, Co, and Ni additions͒ on material properties in L1 0 TiAl has been studied using the first-principles DMol and discrete variational method within the framework of the density-functional theory. The transfer energy calculation indicates that all these 3d elements show a tendency to substitute for Al sites in the stoichiometric TiAl alloy, with the increasing order V Ͻ CrϽ MnϽ NiϽ FeϽ Co. Our results show that the local distortion of crystal lattice around an impurity atom is nonuniform, and it is found that the important influencing factors on the local lattice distortion are the impurity atom size and the site preference. Based on the effects of the doped alloying elements on the structural parameters and mechanical properties, we conclude that the larger bond strength and the smaller axial ratio benefit the ductility.

First‐principles calculations of oxygen adsorption on the Ti3Al (0001) surface

“…1. T Al and T Ti represent a top site of a Ti atom [4] 5.772 0.803 114 À0.279 GGA [10] 5.72 0.81 --LDA [26] 5.64 0.81 --Experiment 5.77 [27] 0.801 [27] 113 [28] À0.29 [29] 3 , would move to the nearest stable sites after structure optimization. H I site is the most stable adsorption site at the Ti (0001) surface (Fig.…”

“…[25] The kinetic energy cut-off for the plane wave basis was set to 500 eV. Brillouin zone integration was made on an 7 × 7 × 7 and 7 × 7 × 1 Monkhorst-Pack k-point mesh for the Ti 3 Al bulk (a hexagonal D0 19 crystal structure) crystal structure and the O-Ti 3 Al (0001) surface systems, respectively. The Gaussian method was employed to determine electron occupancies with a smearing parameter σ of 0.1 eV.…”

Preferential site occupancy of alloying elements in TiAl-based phases

“…V, Zr, Nb, Mo, Ta, and W have been reported to occupy Ti-sites in the γ-phase 8,10-16,21,34 , in agreement with our predictions. Some controversy remains in the case of Cr: While most recent reports suggest preference for Al-substitution7,10,11,15,16,20 , others suggested preference for…”

Site Selection and Pseudo-Clustering Behaviors of Alloying Elements in Aluminum-Lean γ-TiAl Intermetallics

“…The site selection characteristics of Fe, Co, and Ni agree well with the experiments. [15][16][17]20,21] As far as Al-lean c-TiAl are considered, our predictions are in full agreement with the experimental data reported for Al sublattice site occupants, i.e., Mn, [15][16][17]21,23,25] V, [15,21] Ga, [16][17][18]20,21,26] Si, [24] Pd, [12] and Cr, [15,17,24] as well as Ti sublattice occupants, i.e., Y, [20,21] Zr, [16,17,19,20,22] Nb, [16,17,20,[22][23][24] Mo, [20,21] Hf, [16,17,25,26] Ta and W, [16,17,24] and Ge and Sb. [21] However, contradictions arise for the alloying additions as M = Mn, Cr, and V, each of which are reported to occupy either Ti sites, …”

“…Although a compromise is achieved for several alloying elements such as Nb, Zr, and Ga, [16][17][18][19][20][21][22]24,26] there are significant disparities in site preference of Cr, Mn, and V [13,[15][16][17][18][19][23][24][25] in c-TiAl reported to date. Besides, there still remain various elements such as Cu, Zn, Ag, and Au, whose site occupations in c-TiAl are unexplored or not debated but worthy of investigation.…”