First-Principle Investigation into Mechanical Properties of Al₆Mg₁Zr₁ under Uniaxial Tension Strain on the Basis of Density Functional Theory

Abstract

The influences of uniaxial tension strain in the x direction (ε_x) on the mechanical stability, stress–strain relations, elastic properties, hardness, ductility, and elastic anisotropy of Al₆Mg₁Zr₁ compound were studied by performing first-principle calculations on the basis of density functional theory. It was found that Al₆Mg₁Zr₁ compound is mechanically stable in the range of strain ε_x from 0 to 6%. As the strain ε_x increased from 0 to 6%, the stress in the x direction (σ_x) first grew linearly and then followed a nonlinear trend, while the stresses in the y and z directions (σ_y and σ_z) showed a linearly, increasing trend all the way. The bulk modulus B, shear modulus G, and Young’s modulus E all dropped as the strain ε_x increased from 0 to 6%. The Poisson ratio μ of Al₆Mg₁Zr₁ compound was nearly unchanged when the strain ε_x was less than 3%, but then it grew quickly. Vickers hardness H_V of Al₆Mg₁Zr₁ compound dropped gradually as the strain ε_x increased from 0 to 6%. The Al₆Mg₁Zr₁ compound was brittle when the ε_x was less than 4%, but it presented ductility when the strain ε_x was more than 4%. As the strain ε_x increased from 0 to 6%, the compression anisotropy percentage (A_B) grew and its slope became larger when the strain ε_x was more than 4%, while both the shear anisotropy percentage (A_G) and the universal anisotropy index (A_U) first dropped slowly and then grew quickly. These results demonstrate that imposing appropriate uniaxial tension strain can affect and regulate the mechanical properties of Al₆Mg₁Zr₁ compound.

1. Introduction

From an industrial point of view, the aluminum–magnesium (Al-Mg) based alloys and intermetallic compounds are considered as very promising engineering materials, and have been widely used in aviation, aerospace, shipbuilding, rail transportation, and automotive industries owing to their high strength-to-weight ratio, good formability, excellent corrosion resistance, and good weldability [1,2,3,4]. However, Al-Mg based materials only have a low to medium strength, which severely restricts their application in industry [5,6,7]. With the rapid development of industrial technology, a further improvement of the comprehensive performance of Al-Mg based materials is required. An effective approach to improve the performance of the Al-Mg based materials is by adding the appropriate elements [8,9,10,11,12]. The rare-earth metal scandium (Sc) has proved to be the most effective element to improve the performance of the Al-Mg based materials [13,14,15,16]. However, the application of Sc is greatly limited in industry due to its high cost. Therefore, it is of great significance to search for another lower-cost additional element to replace Sc. The transition metal zirconium (Zr) is of much lower cost (its price is only about 1/100 of that of Sc), and can serve a similar strengthening function to Sc in Al-Mg based materials [17,18,19,20,21].

In recent years, it was reported that the functional properties of materials were regulated by imposing strain [22,23,24,25]. Fu, et al. quantitatively analyzed the effects of heterogeneous plastic strain on hydrogen-induced cracking of twinning-induced plasticity (TWIP) steel by electron backscattered diffraction (EBSD) technology. According to a quantitative calculation of EBSD crystallographic data, the larger the geometrically necessary dislocation density (ρ_GND), the greater is the heterogeneous strain. It was evident from the overall statistical analyses that hydrogen-induced crack initiation depends on interactions between heterogeneous strain and hydrogen atoms generated by local grain orientation deviation (deviation from ideal) and gradient (misorientation). The larger the ρ_GND, the easier it is to cause local enrichment of hydrogen atoms, which in turn leads to hydrogen-induced cracking in TWIP steel [26]. Liang et al. investigated the strain-induced strengthening in superconducting β-Mo₂C through high pressure and high temperature. It was found that strain-induced high-density dislocations and low-angle grain boundaries were introduced and enabled the synthesized β-Mo₂C ceramics to exhibit surprising mechanical properties [27]. Du, et al. studied the Poisson ratio of in-plane pristine armchair and zigzag graphene under uniaxial tensile loading by molecular dynamics simulations, which indicated that the Poisson ratio strongly depends on the tensile strain. At the critical strain, the Poisson ratio will transform from positive to negative, and the critical strain of the zigzag is far less than that of armchair [28]. Rasidul Islam, et al. investigated the strain-induced mechanical properties of inorganic halide perovskite CsGeBr₃ through first-principles based on density functional theory. It was found that the bulk modulus, shear modulus, and Young’s modulus all increased with increasing compressive strain but decreased with increasing tensile strain. The brittleness of CsGeBr₃ increased with compressive strain, whereas CsGeBr3 offered significant ductility with more than 2% tensile strain [29]. Tan et al. investigated the mechanical behavior of AlSi₂Sc₂ under uniaxial tensile strain by performing first-principle calculations based on density functional theory. It was found that the estimated elastic moduli of AlSi₂Sc₂ decreased with increasing uniaxial tensile strain, but the brittleness of AlSi₂Sc₂ did not change when strain was applied [30]. However, there has been little investigation into the effect of strain on the mechanical properties of Al-Mg-Zr compounds based on the density functional theory.

In the present study, the first principle calculations based on density functional theory were used to investigate the elastic properties, hardness, ductility, and elastic anisotropy of Al₆Mg₁Zr₁ compound at different uniaxial tensile strains. The current research will contribute to a better understanding of the modulation of strain on the mechanical properties of Al-Mg based alloys and compounds.

2. Computational Methods

In this study, the structural model of Al₆Mg₁Zr₁ supercell viewed along the c axis is shown in Figure 1. Grey, orange, and green spheres represent Al, Mg, and Zr atoms, respectively. The x, y, and z direction are parallel to the a, b, and c axis, respectively. Our calculations of Al₆Mg₁Zr₁ were carried out by the Cambridge Serial Total Energy Package (CASTEP) code, using the plane-wave pseudopotential method based on density functional theory (DFT) [31,32,33]. For the exchange and correlation terms in the electron–electron interaction, the generalized gradient approximation (GGA) in the scheme of Perdew–Burke–Ernzerhof (PBE) was used [34]. The valence wave functions were expanded in a plane-wave basis set up to an energy cutoff of 600 eV. For the k point sampling, a 3 × 6 × 6 Monkhorst–Pack mesh in the Brillouin zone was used. The other parameters used default settings of ultra-fine accuracy.

3. Results and Discussion

3.1. Mechanical Stability

Elastic stiffness constants C_ij are very important physical quantities used to express the elasticity of a solid material in engineering applications. In this work, the elastic stiffness constants were calculated using the stress–strain approach based on Hook’s law by imposing uniaxial tension strain in the x direction (ε_x). The elastic stiffness constants C_ij of Al₆Mg₁Zr₁ compound at different ε_x are presented in

Table 1. Calculated values of the elastic stiffness constants C_ij (in GPa) of Al₆Mg₁Zr₁ at different uniaxial tension strains in x direction (ε_x).

εx (%)	C11	C12	C13	C22	C23	C33	C44	C55	C66
0	157.17	41.58	41.56	170.16	41.57	170.08	40.52	53.70	53.71
1%	146.98	36.34	36.37	163.72	42.30	163.79	42.19	49.69	49.90
2%	136.71	35.30	35.32	156.80	45.54	156.82	44.84	47.06	47.06
3%	124.44	35.59	35.57	146.39	48.13	146.36	48.54	43.25	43.25
4%	111.37	37.46	37.46	133.26	50.68	133.26	51.02	37.65	37.65
5%	94.62	39.78	39.78	118.19	55.44	118.19	50.42	29.91	29.91
6%	65.16	44.63	44.63	99.25	64.20	99.26	46.10	19.98	19.98
7%	17.81	52.18	52.20	75.93	75.41	75.95	40.10	8.17	8.17

. It can be found that there are nine independent effective constants (C₁₁, C₁₂, C₁₃, C₂₂, C₂₃, C₃₃, C₄₄, C_55, and C₆₆) in the elastic stiffness matrix for Al₆Mg₁Zr₁. Therefore, Al₆Mg₁Zr₁ is determined to be of orthorhombic structure [35].

Based on Born–Huang’s dynamical theory of crystal lattices, the mechanical stability standards for orthorhombic crystals must meet the following requirements [36]:

$$\left\{\begin{array}{l}{C}_{ii}>0\\ C_{11}+C_{22}-2C_{12}>0\\ C_{11}+C_{33}-2C_{13}>0\\ C_{22}+C_{33}-2C_{23}>0\\ C_{11}+C_{22}+C_{33}+2(C_{12}+C_{13}+C_{23})>0\end{array}\right.$$

(1)

It was noted that the elastic constants C_ij of the Al₆Mg₁Zr₁ fulfilled well the mechanical stability standards in the range of strain ε_x from 0 to 6%, while they could not meet the standards when the ε_x was more than 6%. Therefore, the orthorhombic of Al₆Mg₁Zr₁ is mechanically stable in the range of strain ε_x from 0 to 6%. In this study, we are only concerned with the mechanical properties of Al₆Mg₁Zr₁ in the range of strain ε_x from 0 to 6%.

3.2. Stress–Strain Relations

The stresses in the principal axis direction (σ_x, σ_y, and σ_z) of Al₆Mg₁Zr₁ at different uniaxial tension strains in the x direction (ε_x) were calculated based on Hook’s law, and the calculated values are presented in

Table 2. Calculated values of stresses in principal axis directions (σ_x, σ_y, and σ_z) of Al₆Mg₁Zr₁ at different uniaxial tension strains in x direction (ε_x).

εx (%)	σx (GPa)	σy (GPa)	σz (GPa)
0	0	0	0
1%	1.57	0.42	0.42
2%	3.04	0.78	0.78
3%	4.41	1.13	1.13
4%	5.65	1.49	1.49
5%	6.77	1.87	1.86
6%	7.71	2.26	2.26

and Figure 2.

It can be seen that, as the strain ε_x increased from 0 to 6%, the stress in the x direction (i.e., σ_x) gradually grew to 7.7129 GPa. The σ_x-ε_x curve of Al₆Mg₁Zr₁ had a linear formation in the range of strain ε_x from 0 to 3%, and then followed a nonlinear trend in the range of strain ε_x from 3% to 6%. It is indicated that the deformation of Al₆Mg₁Zr₁ was elastic in the range of ε_x from 0 to 3%, after which plastic deformation occurred. The stresses in the y and z directions (σ_y and σ_z) were almost equal and had good linear relation with the uniaxial tension strain in the range of ε_x from 0 to 6%. On the whole, the stress σ_x was much higher than σ_y and σ_z due to the uniaxial tension loading being in the x direction.

3.3. Elastic Properties of Polycrystalline Materials

In many cases, polycrystalline materials have advantages in practical applications compared to single crystal materials [37]. Therefore, it is more meaningful to examine the elastic properties of polycrystalline materials. The elastic properties of polycrystalline materials can be characterized by the bulk modulus B, shear modulus G, Young’s modulus E, and Poisson ratio μ.

There are two approximation methods to obtain polycrystalline elastic moduli, namely, the Voigt method and the Reuss method. The Voigt method provides the upper bound to the polycrystalline elastic moduli, and the Reuss method provides the lower bound to the polycrystalline elastic moduli. For different crystalline systems, the bulk modulus B and shear modulus G according to Voigt and Reuss approximations are given by the following equations [38]:

$$B_{\mathrm{V}}=\frac{C_{11}+C_{22}+C_{33}+2(C_{12}+C_{13}+C_{23})}{9}$$

(2)

$$G_{\mathrm{V}}=\frac{C_{11}+C_{22}+C_{33}-C_{12}-C_{13}-C_{23}}{15}+\frac{C_{44}+C_{55}+C_{66}}{5}$$

(3)

$$B_{\mathrm{R}}=\frac{1}{S_{11}+S_{22}+S_{33}+2(S_{12}+S_{13}+S_{23})}$$

(4)

$$G_{\mathrm{R}}=\frac{15}{4(S_{11}+S_{22}+S_{33})+3(S_{44}+S_{55}+S_{66})-4(S_{12}+S_{13}+S_{23})}$$

(5)

where the subscripts V and R denote the Voigt and Reuss averages, C_ij are the elastic stiffness constants, and S_ij are the elastic compliance coefficients.

The arithmetic average of the Voigt and the Reuss bounds is referred to as the Voigt–Reuss Hill (VRH) average, and it is considered as the best estimate of the theoretical polycrystalline elastic moduli. The VRH averages of B and G are given as follows [38]:

$$B=\frac{B_{\mathrm{V}}+B_{\mathrm{R}}}{2}$$

(6)

$$G=\frac{G_{\mathrm{V}}+G_{\mathrm{R}}}{2}$$

(7)

The Young’s modulus E and Poisson ratio μ of the polycrystalline material can be obtained from the bulk modulus B and shear modulus G, while the corresponding calculation formulas are as follows [38]:

$$E=\frac{9BG}{3B+G}$$

(8)

$$\mu =\frac{3B-2G}{6B+2G}$$

(9)

The Bulk modulus B, shear modulus G, Young’s modulus E and Poisson ratio μ of polycrystalline Al₆Mg₁Zr₁ at different uniaxial tension strains in the x direction (ε_x) were calculated using the above formulas, and the calculated values are presented in

Table 3. Calculated values of the elastic moduli (B, G, and E) and Poisson ratios μ of polycrystalline Al₆Mg₁Zr₁ at different uniaxial tension strains in x direction (ε_x).

εx (%)	B (GPa)	G (GPa)	E (GPa)	μ
0	82.93	53.77	132.63	0.23
1%	78.12	51.81	127.28	0.23
2%	75.55	49.82	122.53	0.230
3%	72.43	46.72	115.36	0.24
4%	69.37	41.76	104.34	0.25
5%	65.94	34.36	87.81	0.28
6%	60.63	22.88	60.96	0.33

and Figure 3.

The bulk modulus B is a measure of the resistance of a solid material to a volume change. Figure 3a presents the calculated bulk modulus B of Al₆Mg₁Zr₁ at different strains ε_x. It can be seen that, as the strain ε_x increased from 0 to 6%, the bulk modulus B dropped from 82.93 GPa to 60.63 GPa. The bulk modulus B reduced by 26.9%, which showed its negative relation with the uniaxial tension strain for Al₆Mg₁Zr₁. The Al₆Mg₁Zr₁ alloy has the largest incompressibility at the unstrained state due to the largest B value, while it has the largest compressibility at the strain ε_x of 6% due to the smallest B value.

The shear modulus G is defined as the ratio of shear stress to the shear strain, which characterizes the ability of a solid material to resist deformation under shear stress. The greater G corresponds to the stronger shear resistance of the solid material. Figure 3b presents the calculated values of shear modulus G of Al₆Mg₁Zr₁ at different strains ε_x. It can be seen that as the strain ε_x increased from 0 to 6%, the shear modulus G dropped from 53.77 GPa to 22.88 GPa. The shear modulus G was reduced by 57.5%, which indicated that shear resistance is greatly influenced by the uniaxial tension strain. Al₆Mg₁Zr₁ alloy has the smallest shear resistance at the strain ε_x of 6% due to the smallest G value.

Young’s modulus E is defined as the ratio of tensile stress and axial strain and serves as a measure of the stiffness of solid materials. Figure 3c presents the calculated values of Young’s modulus E of Al₆Mg₁Zr₁ at different strains ε_x. It can be found that Young’s modulus E dropped with increasing strain ε_x. When the Al₆Mg₁Zr₁ was unstrained, the Young’s modulus E was 132.63 GPa. When the strain ε_x reached 6%, Young’s modulus E dropped to 60.96 GPa. Young’s modulus E was reduced by 54.0%, showing its negative relation with uniaxial tension strain. The unstrained Al₆Mg₁Zr₁ has the largest stiffness due to the largest E value, while Al₆Mg₁Zr₁ alloy has the smallest stiffness at the strain ε_x of 6% due to the smallest E value.

Figure 3d presents the calculated values of Poisson ratio μ of Al₆Mg₁Zr₁ at different strains ε_x. It can be found that when the strain ε_x was less than 3%, the Poisson ratio μ remained nearly unchanged. When ε_x was more than 3%, the Poisson ratio μ grew quickly with increasing strain ε_x, showing its positive relation with uniaxial tension strain. Generally, when the Poisson ratio μ is between −1 and 0.5, the solid is relatively stable under shear deformation. From Figure 3d, it can be seen that the Poisson ratio μ of Al₆Mg₁Zr₁ ranged from 0.23 to 0.33, which is between −1 and 0.5, indicating that Al₆Mg₁Zr₁ is a stable linear elastic solid. Al₆Mg₁Zr₁ has the maximum μ value at the strain ε_x of 6%, indicating that Al₆Mg₁Zr₁ has the highest toughness at the strain ε_x of 6%.

By comparing Figure 3a–c and Figure 3d, it can be found that with the strain ε_x increasing from 0 to 6%, the elastic moduli (B, G, and E) monotonically decreased with the increasing strain ε_x, while the Poisson ratio μ was first nearly unchanged and then grew quickly. The variation trends of elastic moduli (B, G, and E) and Poisson ratio μ of Al₆Mg₁Zr₁ alloy with the uniaxial tensile strain ε_x are similar to that of AlSi₂Sc₂ [30].

3.4. Hardness and Ductility

Hardness is a measure of the resistance to localized deformation induced by either mechanical indentation or abrasion. In general, hardness is linked with the elastic and plastic properties of a material, and the shear modulus G is the more important parameter governing hardness than the bulk modulus B. There have been some semi-empirical models developed to predict the hardness of materials. Chen et al. [39] proposed a model to predict the Vickers hardness H_V of polycrystalline materials and bulk metallic glasses based on the shear modulus G and the Pugh’s modulus ratio k (k = G/B) as follows [39]:

$$H_{\mathrm{V}}=1.887k^{1.171}{G}^{0.591}$$

(10)

The above formula has been successfully used to predict the hardness of many compounds.

The ductility or brittleness of a solid material can be estimated by the ratio of the bulk modulus B to the elastic shear modulus G (i.e., B/G). If the modulus ratio B/G is more than 1.75, the solid is classified as ductile material; otherwise, it is brittle [40,41].

Table 4. Calculated values of the Vickers hardness H_V and the modulus ratio B/G of Al₆Mg₁Zr₁ at different uniaxial tension strains in x direction (ε_x).

εx (%)	HV (GPa)	B/G
0	11.97	1.54
1%	12.03	1.51
2%	11.67	1.52
3%	10.95	1.55
4%	9.45	1.66
5%	7.11	1.92
6%	3.83	2.65

and Figure 4 present the calculated values of Vickers hardness H_v and the modulus ratio B/G of Al₆Mg₁Zr₁ at different uniaxial tension strains ε_x.

From Figure 4a, as the strain ε_x increased from 0 to 6%, the Vickers hardness H_V of Al₆Mg₁Zr₁ dropped gradually from 11.97 GPa to 3.83 Gpa. The Vickers hardness H_V of Al₆Mg₁Zr₁ dropped by 71.746%, showing its negative relation with the uniaxial tension strain.

From Figure 4b, when the strain ε_x was less than 3%, the modulus ratio B/G remained nearly unchanged. When the ε_x was more than 3%, the modulus ratio B/G grew quickly from 1.55 to 2.65 with the increasing strain ε_x. When the strain ε_x was less than 4%, the modulus ratio B/G < 1.75 and the Al₆Mg₁Zr₁ was brittle. When the ε_x was more than 4%, the modulus ratio B/G > 1.75 and the Al₆Mg₁Zr₁ was taken as ductile. Al₆Mg₁Zr₁ would become most ductile at the strain of 6% due to the largest modulus ratio B/G value of 2.65.

3.5. Elastic Anisotropy

Elastic anisotropy of a solid material is very important in diverse applications such as phase transformations and dislocation dynamics, and it can be characterized by the elastic anisotropy indexes. The elastic anisotropy indexes include compression anisotropy percentage A_B, shear anisotropy percentage A_G, and the universal anisotropy index A_U, and can be calculated using the following expressions [42]:

$$\left\{\begin{array}{l}{A}_{\mathrm{B}}=\frac{B_{\mathrm{V}}-B_{\mathrm{R}}}{B_{\mathrm{V}}+B_{\mathrm{R}}}\\ A_{\mathrm{G}}=\frac{G_{\mathrm{V}}-G_{\mathrm{R}}}{G_{\mathrm{V}}+G_{\mathrm{R}}}\\ A_{\mathrm{U}}=5\frac{G_{\mathrm{V}}}{G_{\mathrm{R}}}+\frac{B_{\mathrm{V}}}{B_{\mathrm{R}}}-6\end{array}\right.$$

(11)

If A_U = A_B = A_G = 0, the material shows characteristics of elastic isotropy. Otherwise, it has elastic anisotropy, and the larger the deviation of elastic anisotropy index values from 0 (the corresponding elastic isotropy value), the greater its degree in elastic anisotropy.

Table 5. Calculated values of elastic anisotropy indexes (A_B, A_G, and A_U) of Al₆Mg₁Zr₁ at different uniaxial tension strains in x direction (ε_x).

εx (%)	AB	AG	AU
0	0.06%	1.26%	0.13
1%	0.21%	0.92%	0.10
2%	0.40%	0.50%	0.06
3%	0.60%	0.32%	0.04
4%	0.77%	0.77%	0.09
5%	1.27%	2.20%	0.25
6%	4.58%	7.37%	0.89

and Figure 5 show the calculated values of elastic anisotropy indexes (A_B, A_G, and A_U) of Al₆Mg₁Zr₁ at different uniaxial tension strains ε_x.

From Figure 5a, the compression anisotropy percentage A_B of Al₆Mg₁Zr₁ grew slowly as the strain ε_x increased from 0 to 4%, and then it grew quickly as the strain ε_x increased from 4% to 6%. A_B reached its maximum of 4.58% at the strain ε_x of 6%. From Figure 5b, when the strain ε_x was less than 3%, the shear anisotropy percentage A_G dropped slowly with the strain ε_x. A_G reached its minimum of 0.32% at the strain ε_x of 3%. When the strain ε_x was more than 3%, A_G grew quickly with the strain ε_x, and reached its maximum of 7.37% at the strain ε_x of 6%. The universal anisotropy index A_U can reflect the anisotropy more accurately because both bulk modulus B and shear modulus G are deliberated in its expression. As shown in Figure 5c, the change trend of A_U with the strain ε_x is similar to that of A_G. The variation trends of elastic anisotropy indexes of Al₆Mg₁Zr₁ with uniaxial tensile strain are similar to that of hexagonal C40 MoSi₂ [43]. Moreover, the values of the elastic anisotropy indexes (A_B, A_G, and A_U) are small and the degree in elastic anisotropy of Al₆Mg₁Zr₁ is relatively weak in the range of strain ε_x from 0 to 6%.

4. Conclusions

To sum up, in this work the mechanical stability, stress–strain relations, elastic properties, hardness, ductility, and elastic anisotropy of Al₆Mg₁Zr₁ at different uniaxial tension strains in the x direction (ε_x) were examined by first principle calculations based on density functional theory. The influences of strain ε_x on the mechanical properties of the Al₆Mg₁Zr₁ were studied. It was found that Al₆Mg₁Zr₁ was mechanically stable in the range of strain ε_x from 0 to 6%, while it was unstable when the strain ε_x was more than 6%. As the strain ε_x increased from 0 to 6%, the stress in the x direction (σ_x) first increased linearly and then followed a nonlinear trend, but the stresses in the y and z directions (σ_y and σ_z), which were almost equal, showed a linear, increasing trend all the way. Due to the uniaxial tension loading in the x direction, the stress σ_x was much higher than σ_y and σ_z. The bulk modulus B, shear modulus G and Young’s modulus E of Al₆Mg₁Zr₁ all dropped with increasing strain ε_x from 0 to 6%, showing their negative relations with uniaxial tension strain. Therefore, the incompressibility, shear resistance, and stiffness of the Al₆Mg₁Zr₁ all dropped with increasing uniaxial tension strain. When the strain ε_x was less than 3%, The Poisson ratio μ of Al₆Mg₁Zr₁ was nearly unchanged. However, it grew quickly when the ε_x was more than 3%, showing its positive relation with uniaxial tension strain. The Poisson ratio μ ranged from 0.23 to 0.33, which is between −1 and 0.5, indicating that Al₆Mg₁Zr₁ is stable linear elastic solid in the range of ε_x from 0 to 6%. Al₆Mg₁Zr₁ has the highest toughness at the strain ε_x of 6% due to the maximum μ value. The Vickers hardness H_V of Al₆Mg₁Zr₁ dropped gradually with the increasing strain ε_x from 0 to 6%, showing its negative relation with uniaxial tension strain. When the strain ε_x was less than 3%, the modulus ratio B/G of Al₆Mg₁Zr₁ remained nearly unchanged but it grew quickly when the ε_x was more than 3%, showing its positive relation with uniaxial tension strain. Al₆Mg₁Zr₁ was brittle when the ε_x was less than 4%, while it exhibited ductility when the strain ε_x was more than 4%. The best ductility was achieved for Al₆Mg₁Zr₁ alloy at the strain ε_x of 6% due to the maximum B/G value. The compression anisotropy percentage A_B of Al₆Mg₁Zr₁ grew slowly as the strain ε_x increased from 0 to 4%, while it grew quickly as the strain ε_x increased from 4% to 6%. Both the shear anisotropy percentage (A_G) and universal anisotropy index (A_U) dropped slowly with increasing strain ε_x from 0 to 3%, and then grew quickly with increasing strain ε_x from 3 to 6%. In addition, the values of the elastic anisotropy indexes (A_B, A_G, and A_U) are small and the degree in elastic anisotropy of Al₆Mg₁Zr₁ is relatively weak in the range of ε_x from 0 to 6%. These results show that applying uniaxial tension strain is an effective and promising strategy to improve the mechanical properties of Al₆Mg₁Zr₁.