Mechanical properties of defective L1_2-Al_3X(X=Sc,Lu) phase:A first-principles study |
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| Authors: | Yu Wang Ya'nan Meng Junsheng Wang Chi Zhang Houbing Huang |
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| Affiliation: | 1. School of Materials Science and Engineering, Beijing Institute of Technology, Beijing 100081, China;2. Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing 100081, China |
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| Abstract: | The mechanical properties of Al_3 X(X=Sc,Lu) were studied by density functional theory(DFT).The elastic constants and formation enthalpy indicate that the L1_2-Al_3 X(X=Sc and Lu) are mechanically and thermodynamically stable.The bulk moduli and shear moduli show that Al_3 Sc has better resistance to volume and shape changes than AI3 Lu.However,the calculated results show that Al_3 Lu has better plasticity than Al_3 Sc.The properties of structural stability and elastic moduli of the crystal containing four major types of point defects in L1_2-Al_3 X(X=Sc and Lu) were calculated.The mechanical properties of point defects show that point defects cause L1_2-Al_3 X lattice distortion and change the corresponding elastic constants.Point defects reduce the Young's,shear and bulk moduli but have little effects on the crystal brittleness and toughness of Al_3 Sc and Al_3 Lu.Therefore,we have found that Lu addition into aluminum alloys is a very good replacement for expensive Sc addition when the L1_2 structures are desired for nucleation or strengthening precipitates in aluminum alloys. |
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| Keywords: | Density functional theory First-principle Mechanical property Defects Rare earths |
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