The Effect of Alloying Elements on the Structural Stability, Mechanical Properties, and Debye Temperature of Al(3)Li: A First-Principles Study

The structural stability, mechanical properties, and Debye temperature of alloying elements X (X = Sc, Ti, Co, Cu, Zn, Zr, Nb, and Mo) doped Al(3)Li were systematically investigated by first-principles methods. A negative enthalpy of formation ΔH(f) is predicted for all Al(3)Li doped species which has consequences for its structural stability. The Sc, Ti, Zr, Nb, and Mo are preferentially occupying the Li sites in Al(3)Li 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 C(ij) 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 Al(3)Li. The Al(6)LiSc 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 A(U) for pure and doped Al(3)Li is higher than 0, implying the anisotropy of Al–Li–X alloy. The Debye temperature Θ(D) of Al(12)Li(3)Ti 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.