Abstract
The structural stability, mechanical properties, and Debye temperature of alloying elements X (X = Sc, Ti, Co, Cu, Zn, Zr, Nb, and Mo) doped Al3Li were systematically investigated by first-principles methods. A negative enthalpy of formation ΔHf is predicted for all Al3Li doped species which has consequences for its structural stability. The Sc, Ti, Zr, Nb, and Mo are preferentially occupying the Li sites in Al3Li while the Co, Cu, and Zn prefer to occupy the Al sites. The Al–Li–X systems are mechanically stable at 0 K as elastic constants Cij has satisfied the stability criteria. The values of bulk modulus B for Al–Li–X (X = Sc, Ti, Co, Cu, Zr, Nb, and Mo) alloys (excluding Al–Li–Zn) increase with the increase of doping concentration and are larger than that for pure Al3Li. The Al6LiSc has the highest shear modulus G and Young’s modulus E which indicates that it has stronger shear deformation resistance and stiffness. The predicted universal anisotropy index AU for pure and doped Al3Li is higher than 0, implying the anisotropy of Al–Li–X alloy. The Debye temperature ΘD of Al12Li3Ti is highest among the Al–Li–X system which predicts the existence of strong covalent bonds and thermal conductivity compared to that of other systems.
Highlights
IntroductionLightweight structural materials such as the Al–Li based alloys have excellent comprehensive performance, such as low density, good corrosion resistance, and high elastic modulus [1,2], and it is the basic reason why Al–Li based alloys are so widely used in aviation and aerospace field
Lightweight structural materials such as the Al–Li based alloys have excellent comprehensive performance, such as low density, good corrosion resistance, and high elastic modulus [1,2], and it is the basic reason why Al–Li based alloys are so widely used in aviation and aerospace field.The metastable Al3 Li (δ0 ) precipitates has an important influence on the mechanical properties ofAl–Li based alloys [3,4]
All the Cij of Al–Li–X (X =Sc, Ti, Zr, and Nb) systems are higher than those of pure Al3 Li, which indicate that the doping elements X (X =Sc, Ti, Zr, and Nb) can effectively improve the Cij of pure Al3 Li
Summary
Lightweight structural materials such as the Al–Li based alloys have excellent comprehensive performance, such as low density, good corrosion resistance, and high elastic modulus [1,2], and it is the basic reason why Al–Li based alloys are so widely used in aviation and aerospace field. The δ0 precipitates are considered the most important strengthening phases of Al–Li alloys [9]. The formation formation enthalpy, enthalpy, ofcoarsening coarseningkinetics kineticsofofδ′δ0 precipitates precipitates in in the the binary Al–Li electronic structures, and vibrational and thermodynamic properties of the δ′. Phase were electronic structures, and vibrational and thermodynamic properties of the δ phase were systematically systematically reportedthe by employing the first-principles methods [16,17,18,19,20,21]. Al–Li alloys provide limited room temperature strength due phase [22]. The δ phase in binary Al–Li alloys provide limited room temperature strength dueto. No one has reported the influences of alloying to improve the specific properties of alloys.
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