Coherent phase stability in Al-Zn and Al-Cu fcc alloys: The role of the instability of fcc Zn

Müller, Stefan; Wang, L.-W.; Zunger, Alex; Wolverton, Chris

doi:10.1103/physrevb.60.16448

Cited by 62 publications

(57 citation statements)

References 66 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Born criteria, which followed from the determinant condition jCj ¼ 0, are now replaced by criteria derived from jAj ¼ 0, where A ¼ ðB T þ BÞ=2 and superscript T denotes transposition . In the special case of hydrostatic pressure, 11 ¼ 22 ¼ 33 ¼ ÀP, the new conditions for elastic stability are (Wallace, 1967;Hill, 1979a, 1979b;Wang et al, 1993Wang et al, , 1995Mizushima, Yip, and Kaxiras, 1994;Zhou and Joós, 1996;Morris, Jr. and Krenn, 2000;Yip et al, 2001)…”

Section: Elastic Stability Under External Loadmentioning

confidence: 99%

Lattice instabilities in metallic elements

et al. 2012

View full text Add to dashboard Cite

Most metallic elements have a crystal structure that is either body-centered cubic (bcc), facecentered close packed, or hexagonal close packed. If the bcc lattice is the thermodynamically most stable structure, the close-packed structures usually are dynamically unstable, i.e., have elastic constants violating the Born stability conditions or, more generally, have phonons with imaginary frequencies. Conversely, the bcc lattice tends to be dynamically unstable if the equilibrium structure is close packed. This striking regularity essentially went unnoticed until ab initio total-energy calculations in the 1990s became accurate enough to model dynamical properties of solids in hypothetical lattice structures. After a review of stability criteria, thermodynamic functions in the vicinity of an instability, Bain paths, and how instabilities may arise or disappear when pressure, temperature, and/or chemical composition is varied are discussed. The role of dynamical instabilities in the ideal strength of solids and in metallurgical phase diagrams is then considered, and comments are made on amorphization, melting, and low-dimensional systems. The review concludes with extensive references to theoretical work on the stability properties of metallic elements.

show abstract

Section: Elastic Stability Under External Loadmentioning

confidence: 99%

Lattice instabilities in metallic elements

et al. 2012

View full text Add to dashboard Cite

show abstract

“…First principles calculations are ideally suited to study coherent phase stability in the IV-VI rocksalt alloys. Density functional theory (DFT) calculations have been applied to phase stability problems in metallic alloys, [23][24][25][26][27][28][29][30][31][32][33] semiconductor alloys, [34][35][36][37][38][39][40][41] and oxide systems [42][43][44][45][46][47] with great success. Lead chalcogenide compounds and alloys have also been studied extensively with DFT, focusing mostly on either the electronic structure [48][49][50][51][52][53][54][55][56][57][58][59][60][61][62] or lattice dynamics 41,[63][64][65][66][67][68][69] o...…”

Section: Fig 1 (Color Online) Schematic Phase Diagram Of a Pseudo-bmentioning

confidence: 99%

“…(16), and the coherency strain energy along , Eq. (9), gives a quantity we define as the chemical energy of the ordered structure, 26 ∆ ℎ , ≡∆ , −∆ , .…”

Section: Mixing Enthalpiesmentioning

confidence: 99%

Coherent and incoherent phase stabilities of thermoelectric rocksalt IV-VI semiconductor alloys

Doak

Wolverton

2012

Phys. Rev. B

Self Cite

View full text Add to dashboard Cite

Nanostructures formed by phase separation improve the thermoelectric figure of merit in lead chalcogenide semiconductor alloys, with coherent nanostructures giving larger improvements than incoherent nanostructures. However, large coherency strains in these alloys drastically alter the thermodynamics of phase stability. Incoherent phase stability can be easily inferred from an equilibrium phase diagram, but coherent phase stability is more difficult to assess experimentally. Therefore, we use density functional theory calculations to investigate the coherent and incoherent phase stability of the IV-VI rocksalt semiconductor alloy systems Pb(S,Te), Pb(Te,Se), Pb(Se,S), (Pb,Sn)Te, (Sn,Ge)Te, and (Ge,Pb)Te. Here we use the term coherent to indicate that there is a common and unbroken lattice between the phases under consideration, and we use the term incoherent to indicate that the lattices of coexisting phases are unconstrained and allowed to take on equilibrium volumes. We find that the thermodynamic ground state of all of the IV-VI pseudo-binary systems studied is incoherent phase separation. We also find that the coherency strain energy, previously neglected in studies of these IV-VI alloys, is lowest along 111 (in contrast to most fcc metals), and is a large fraction of the thermodynamic driving force for incoherent phase separation in all systems. The driving force for coherent phase separation is significantly reduced, and we find that coherent nanostructures can only form at low temperatures where kinetics may prohibit their precipitation. Furthermore, by calculating the energies of ordered structures for these systems we find that the coherent phase stability of most IV-VI systems favors ordering over spinodal decomposition. Our results suggest that experimental reports of spinodal decomposition in the IV-VI rocksalt alloys should be re-examined. PACS number(s): 64.75. Nx, 82.60.Nh, 84.60.Rb, 64.70.kg 2

show abstract

“…It should be noted that in cases (e.g., A1-CU) where the lowest-energy coherent configurations correspond to ordered compounds which have a large degree of "clustering", ofie can obtain clustering-type SRO even in a "Type I" alloy (see Ref. [14]). In this paper, we study these types I-V of LRO/SRO behavior in real alloy systems using a first-principles total energy technique for calculating AHO and A13cs, and a cluster expansion method for calculating AHR and SRO.…”

Section: Ah~=mentioning

confidence: 99%

Short-range-order types in binary alloys: a reflection of coherent phase stability

Wolverton¹,

Ozoliņš²,

Zunger³

2000

J. Phys.: Condens. Matter

Self Cite

View full text Add to dashboard Cite

Ci3s'ri"" authored by a contractor of the Un&-StatGovernment under contraAccordingly the United States Gov. srnment retains a non -exclusive royalty-free license to publish or re. produce the published form of thie ....The short-range order (SRO) present in disordered solid solutions is classified according to three characteristicsystem-dependent energies: (1) formation enthalpiesof ordered compounds, (2) enthalpiesof mixing of disordered alloys, and (3) the energy of coherent phase separation, (the compositionweighted energy of the constituents each constrained to maintain a common lattice constant along an A/B interface). These energies are all compared agaimt a common reference, the energy of incoherent phase separation (the composition-weightedenergyof the constituentseach at their own equilibrium volumes). UnlikeIong-rangeorder (LRO), short-rangeorder is determined by energetic competition between phases at a jized composition, and hence only coherentphase-separated states are of relevance for SRO. We find five distinct SRO types, and show examples of each of these five types, including CU-AU,A1-Mg, GaP-InP, Ni-Au, and Cu-Ag. AbstractThe short-rangeorder (SRO) present indisordered solid solutions is classified according to three characteristicsystem-dependent energies: (1) formation enthaIpiesof ordered compounds, (2) enthalpiesof mixing of disordered alloys, and (3) the energy of coherent phase separation, (the compositionweighted energy of the constituents each constrained to maintain a common lattice constant along an A/13 interface). These energies are all compared against a common reference, the energy of incoherent phase separation (the composition-weightedenergyoft he constituentseach at their own equilibrium volumes). UnlikeIong-rangeorder (LRO), short-rangeorder is determined by energetic competition between phases at a j'%ed composition, and hence only coherent phase-separated states are of relevancefor SRO. We find five distinct SRO types, and show examples of each of these five types, including CU-AU,A1-Mg, GaP-InP, Ni-Au, and Cu-Ag. The SRO is calculated from 1 . first-principlesusing the mixed-space cluster expansion approach combined .

show abstract

Coherent phase stability in Al-Zn and Al-Cu fcc alloys: The role of the instability of fcc Zn

Cited by 62 publications

References 66 publications

Lattice instabilities in metallic elements

Lattice instabilities in metallic elements

Coherent and incoherent phase stabilities of thermoelectric rocksalt IV-VI semiconductor alloys

Short-range-order types in binary alloys: a reflection of coherent phase stability

Contact Info

Product

Resources

About