Structural, thermodynamics and elastic properties of Mg₁₇Al₁₂, Al₂Y and Al₄Ba phases by first-principles calculations

Abstract

Structural stabilities, thermodynamics stabilities, elastic properties and electronic structures of Mg₁₇Al₁₂, Al₂Y and Al₄Ba phases were analyzed by first-principles calculations with Castep and Dmol3 program based on the density functional theory. The calculated results of heat of formation indicate that Al₂Y phase has the strongest alloying ability. The calculated thermodynamic properties show that the thermal stability of these compounds gradually increases in the order of Mg₁₇Al₁₂, Al₂Y and Al₄Ba phases. Y or Ba addition to the Mg-Al alloys could improve the heat resistance. The calculated bulk modulus B, shear modulus G, elastic modulus E and Poisson ratio ν show that the adding Y or Ba to Mg-Al alloys could promote the brittleness and stiffness, and reduce tenacity and plasticity by forming Al₄Ba and Al₂Y phases. The calculated cohesive energy and density of state (DOS) show that Al₂Y has the strongest structural stability, then Al₄Ba and finally Mg₁₇Al₁₂. The calculated electronic structures show that Al₂Y has the strongest structure stability because of the strong ionic bonds and covalent bonds combined action.

Keywords

Mg-Al alloys / thermodynamics properties / elastic properties / electronic structure / first-principles

References

[1] MordikB. L., EbretT.. Magnesiums: Properties-applications-potential [J]. Mater Sci Eng A, 2001, 302(1): 37-45

[2] LuoA., PekguleryuzM. O.. Cast magnesium alloys for elevated temperature application [J]. J Mater Sci, 1994, 29(20): 5259-5271

[3] ZhangJ.-w., XuB.-she.. Effects of Y on microstructure and mechanical properties of as-cast AZ31 magnesium alloy [J]. Journal of North University of China, 2009, 30(2): 192-196

[4] LiJ.-f., GengH.-r., TengX.-ying.. Effects of Ba on microstructure and mechanical properties of AZ91 magnesium alloy [J]. Hot Working Technology, 2005, 34(7): 5-7

[5] LiuS.-h., DuY., ChenH.-lin.. A thermodynamic reassessment of the Al-Y system [J]. Computer Coupling of Phase Diagrams and Thermochemistry, 2006, 30(3): 334-340

[6] LiuS.-h., DuY., XuH.-hui.. Experimental investigation of the Al-Y phase diagram [J]. Journal of Alloys and Compounds, 2006, 414(1/2): 60-65

[7] ZhaoZ.-d., ChenQ., WangY.-bin.. Microstructures and mechanical properties of AZ91D alloys with Y addition [J]. Materials Science and Engineering A, 2009, 515(1/2): 152-161

[8] TaoX.-m., OuyangY.-f., LiuH.-shan.. Ab initio calculation of the total energy and elastic properties of Laves phase C15 Al 2 RE (RE=Sc, Y, La, Ce-Lu) [J]. Computational Materials Science, 2008, 44(2): 392-399

[9] ZhangG.-y., ZhnagH., FangG.-l., LiY.-cai.. A study on the mechanism of the influence of Bi, Sb alloying on microstructure and properties of AZ91 magnesium alloy [J]. Acta Physica Sinica, 2005, 54(11): 5288-5292

[10] DuW.-w., SunY.-s., MinX.-g., XueF., WuD.-yun.. Influence of Ca addition on valence electron structure of Mg17Al12 [J]. Chinese Nonferrous Metals, 2003, 13(6): 1247-1280

[11] AntonH., SchmidtP. C.. Theoretical investigations of the elastic constants in Caves phases [J]. Intermetallics, 1997, 5(6): 449-465

[12] SongY., GuoZ. X., YangR., LiD.. First principles study of site substitution of ternary elements in NiAl [J]. Acta Mater, 2001, 49(9): 1647-1654

[13] ShiD.-m., WenB., RoderickM., YaoS., LiT.-ju.. First-principles studies of Al-Ni intermetallic compounds [J]. J Solid State Chem, 2009, 182(10): 2664-2669

[14] FaganS. B., MotaR., BaierleR. J., PaivaG., SilaA. J. R. D., FazzioA.. Stability investigation and thermal behavior of a hypothetical silicon nanotube [J]. J Molecular Struct, 2001, 539(1): 101-106

[15] PackJ. D., MonkhorstH. J.. Special points for Brillouin-zone integrations-A reply[J]. Phys Rev B, 1977, 16(4/15): 1748-1749

[16] PerdewJ. P., BurkeK., ErnzerhofM.. Generalized gradient approximation made simple [J]. Phys Rev Lett, 1996, 77(18/28): 3865-3868

[17] NylenJ., GarciaF. J., MoselB. D.. Structure relationships, phase stability and bonding of compounds PdSn n (n=2, 3, 4) [J]. Solid State Sci, 2004, 6(1): 147-155

[18] ZhangL. G., ChenH. M., DongH. Q.. Thermodynamic description of the Al-Sb-Y system [J]. J Alloys Comps, 2009, 475(1/2): 233-237

[19] OuyangY.-f., TaoX.-m., ChenH.-mei.. First-principles calculations of mechanical and thermodynamic properties of the Laves C15-Mg2RE (RE=La, Ce, Pr, Nd, Pm, Sm, Gd) [J]. Computational Materials Science, 2009, 47(2): 297-301

[20] JungW. G., KleppaO. J., ToporL.. Standard molar enthalpies of formation of PdAl, PtAl, ScAl_1.78, YAl₂ and LaAl₂ [J]. J Alloys Compds, 1991, 176(2): 309-318

[21] ChenL., PengP., LiG.-fa.. First-principle calculation of point defective structures of B2-RuAl intermetallic compound [J]. Rare Metal Mater Eng, 2006, 35(7): 1065-1170

[22] ZhouD. W., LiuJ. S., XuS. H.. Thermal stability and elastic properties of Mg₃Sb₂ and Mg₃Bi₂ phases from first-principles calculations [J]. Physica B, 2010, 405(13): 2863-2868

[23] ZhouD. W., LiuJ. S., LouY. Z., ZhangC. H.. Mechanism of Sb, Bi alloying on improving heat resistance properties of Mg-Al alloy[J]. Chinese Nonferrous Metals, 2008, 18(1): 118-125

[24] FuC. L., WangX. D., YeY. Y.. Phase stability, bonding mechanism, and elastic constants of Mo5Si3 by first-principles calculation [J]. Intermetallics, 1999, 7(2): 179-184

[25] DengY.-h., WangT.-f., ZhangW.-bing.. Crystal structure of Mg3Pd from first-principles calculations [J]. Trans Nonferrous Met Soc China, 2008, 18(8): 416-420

[26] VelikokhatnyiO. I., KumtaP. N.. First-principles studies on alloying and simplified thermodynamic aqueouschemical stability of calcium-, zinc-, aluminum-, yttrium- and iron-doped magnesium alloys [J]. Acta Biomaterialia, 2010, 6(5): 1698-1704

[27] LiC., HoeJ. L., WuP.. Empirical correlation between melting temperature and cohesive energy of binary laves phases [J]. J Phys Chem Solids, 2003, 64(2): 201-212

[28] KanounM.B., Goumri-SaidS., ReshakA. H.. Theoretical study of mechanical, electronic, chemical bonding and optical properties of Ti₂SnC, Zr₂SnC, Hf₂SnC and Nb₂SnC [J]. Computational Materials Science, 2009, 47(2): 491-500

[29] DelleyB.. Analytic energy derivatives in the numerical local-density-functional approach [J]. J Chem Phys, 1991, 94(11): 7245-7250