| Summary: | The influences of uniaxial tension strain in the <i>x</i> direction (<i>ε</i><sub>x</sub>) on the mechanical stability, stress–strain relations, elastic properties, hardness, ductility, and elastic anisotropy of Al<sub>6</sub>Mg<sub>1</sub>Zr<sub>1</sub> compound were studied by performing first-principle calculations on the basis of density functional theory. It was found that Al<sub>6</sub>Mg<sub>1</sub>Zr<sub>1</sub> compound is mechanically stable in the range of strain <i>ε</i><sub>x</sub> from 0 to 6%. As the strain <i>ε</i><sub>x</sub> increased from 0 to 6%, the stress in the <i>x</i> direction (<i>σ</i><sub>x</sub>) first grew linearly and then followed a nonlinear trend, while the stresses in the <i>y</i> and <i>z</i> directions (<i>σ</i><sub>y</sub> and <i>σ</i><sub>z</sub>) showed a linearly, increasing trend all the way. The bulk modulus <i>B</i>, shear modulus <i>G</i>, and Young’s modulus <i>E</i> all dropped as the strain <i>ε</i><sub>x</sub> increased from 0 to 6%. The Poisson ratio <i>μ</i> of Al<sub>6</sub>Mg<sub>1</sub>Zr<sub>1</sub> compound was nearly unchanged when the strain <i>ε</i><sub>x</sub> was less than 3%, but then it grew quickly. Vickers hardness <i>H</i><sub>V</sub> of Al<sub>6</sub>Mg<sub>1</sub>Zr<sub>1</sub> compound dropped gradually as the strain <i>ε</i><sub>x</sub> increased from 0 to 6%. The Al<sub>6</sub>Mg<sub>1</sub>Zr<sub>1</sub> compound was brittle when the <i>ε</i><sub>x</sub> was less than 4%, but it presented ductility when the strain <i>ε</i><sub>x</sub> was more than 4%. As the strain <i>ε</i><sub>x</sub> increased from 0 to 6%, the compression anisotropy percentage (<i>A</i><sub>B</sub>) grew and its slope became larger when the strain <i>ε</i><sub>x</sub> was more than 4%, while both the shear anisotropy percentage (<i>A</i><sub>G</sub>) and the universal anisotropy index (<i>A</i><sub>U</sub>) first dropped slowly and then grew quickly. These results demonstrate that imposing appropriate uniaxial tension strain can affect and regulate the mechanical properties of Al<sub>6</sub>Mg<sub>1</sub>Zr<sub>1</sub> compound.
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