Mechanical properties of L12 type Al3X (X=Mg, Sc, Zr) from first-principles study

The mechanical properties of L12 type Al3X (X?=?Mg, Sc, Zr) have been investigated by first-principles calculations. The calculated elastic properties showed that Al3Sc was the stiffest and intrinsically brittle, while Al3Mg was the softest and exhibited ductility tendency. The obtained stressstrain curves demonstrated that both of the ideal tensile and shear strengths of Al3Zr were the strongest, followed by Al3Sc and Al3Mg, and Al3Zr was also the most ductile among three phases, which disagreed with the prediction from the calculated elastic properties, indicating that the mechanical properties should be measured from the complete stressstrain relations at both small and large strains. The electronic density of states (DOS) especially the variations of the charge density during the strain loading were investigated to unveil the intrinsic mechanism for the mechanical properties of L12 type Al3X (X?=?Mg, Sc, Zr) phases.