First-principles study of structural, elastic and electronic properties of ZrIr alloy

Structural, elastic, electronic, and thermodynamic properties of MgAgSb investigated by density functional theory

“…For cubic γ-MgAgSb, we obtain C 11 = 70.6 GPa, C 12 = 52.1 GPa, C 44 = 29.8 GPa, which fulfil the mechanical stability conditions of cubic system [(C 11 + 2C 12 ) > 0, C 44 > 0, C 11 > 0, (C 11 − C 12 ) > 0]. [20,21] The obtained elastic constants of tetragonal phases also satisfy the stability conditions: [22] (C 11 −C 12 ) > 0, (C 11 +C 33 − 2C 13 ) > 0, (2C 11 +C 33 + 2C 12 + 4C 13 ) > 0, C 11 > 0, C 33 > 0, C 44 > 0, C 66 > 0. To the best of our knowledge, neither experimental nor theoretical values of elastic moduli for the MgAgSb alloys are available in the literature.…”

Unexpected Ground-State Structure and Mechanical Properties of Ir2Zr Intermetallic Compound

“…Except for IrZr and Ir 2 Zr, consensus has been reached that the intermetallic phases Ir 3 Zr, Ir 3 Zr 5 , IrZr 2 , and IrZr 3 adopt cubic Cu 3 Au-type ( , Z = 1), hexagonal Mn 5 Si 3 -type ( P 6 3 /mcm , Z = 2), tetragonal Al 2 Cu-type ( I 4/ mcm , Z = 4), and tetragonal V 3 S-type ( , Z = 8) structures, respectively. For IrZr, different room-temperature structures, including TiNi-type, FeB-type, and CrB-type, have been proposed, while a new orthorhombic Cmcm structure was experimentally characterized to be the most stable phase for IrZr [ 15 ], and was confirmed by the theoretical work in [ 10 , 16 , 18 ]. However, the crystal structure of Ir 2 Zr is the subject of continuing debate.…”

“…Like Ni-based alloys, Ir-Zr alloys have a two-phase face-centered cubic ( fcc )/L1 2 structure, with the L1 2 (Ir 3 Zr) precipitates coherently embedded in the fcc Ir matrix, and such an alloy with fcc /L1 2 interfaces has been found to have higher strength than the single fcc or L1 2 intermetallic [ 4 , 5 , 6 , 7 , 8 ]. Moreover, it has been demonstrated that, for a given alloy, some unexpected stoichiometric intermetallics would appear in its microstructure during different heating and cooling processes, which would have a great effect on the properties of the alloys [ 9 , 10 , 11 ]. For instance, it has been reported that the phase transformation of IrZr significantly contributes to the great high-temperature shape memory effect for Ir-Zr alloys [ 10 , 11 ].…”

“…Moreover, it has been demonstrated that, for a given alloy, some unexpected stoichiometric intermetallics would appear in its microstructure during different heating and cooling processes, which would have a great effect on the properties of the alloys [ 9 , 10 , 11 ]. For instance, it has been reported that the phase transformation of IrZr significantly contributes to the great high-temperature shape memory effect for Ir-Zr alloys [ 10 , 11 ]. Hence, an insight into the intrinsic properties of the intermetallics, such as their mechanical properties, could be of great practical significance for the design of composite materials.…”

Rapid screening of high-throughput ground state predictions

“…Part of the solution is to leverage the CALculation of PHAse Diagrams (CALPHAD) [7,8,9] framework and the Compound Energy Formalism (CEF) [10,11,12]. Ab-initio electronic structure methods [13,14] are routinely included to augment experimental input in CALPHAD assessments, [15,16,17] but these efforts typically focus on ordered phases. The inclusion of ab initio data for nonstoichiometric phases is less frequently attempted [18,19,20,21] but when it is, it typically relies on the cluster expansion formalism, which is not easily amenable to a high-throughput treatment.…”