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.
Keywords: Al3Li; Debye temperature; alloying elements; doping concentration; first-principles; lightweight structural materials; mechanical properties.