HIGH-STRENGTH AND CORROSION-RESISTANT MAGNESIUM ALLOY MATERIAL AND METHOD FOR FABRICATING SAME

Abstract

A high strength and corrosion-resistant magnesium alloy material, comprising 0.01-1.2 wt % of Ge and 0.01-1.2 wt % of Zn. A high strength and corrosion-resistant magnesium alloy material, comprising the following chemical elements in percentage by weight: Ge: 0.01-1.2%; Zn: 0.01-1.2%; at least one of Mn, Ca, Zr, Sr, and Gd, with a total weight percentage of ≤3%, wherein the percentage by weight of a single element is ≤0.8%; and the balance of Mg and other inevitable impurities. A method for fabricating the above mentioned high strength and corrosion-resistant magnesium alloy material, comprising the steps of: smelting, solid solution heat treatment, and extrusion, wherein in the extrusion step, the extrusion temperature is 180-350° C., the extrusion rate is 0.1-10 mm/s, and the extrusion ratio is 10:1-30:1.

Claims

1. A high strength and corrosion-resistant magnesium alloy material, comprising 0.01-1.2 wt % of Ge and 0.01-1.2 wt % of Zn.

2. The high strength and corrosion-resistant magnesium alloy material of claim 1, wherein the magnesium alloy material has a microstructure including an α-Mg phase and a column-shaped Mg.sub.2Ge intermetallic compound phase.

3. The high strength and corrosion-resistant magnesium alloy material of claim 1, wherein the magnesium alloy material has a yield strength of higher than 260 MPa, and a corrosion weight loss of less than 0.8 mg/(cm.sup.2 day).

4. A high strength and corrosion-resistant magnesium alloy material, comprising the following chemical elements in percentage by weight: Ge: 0.01˜1.2%; Zn: 0.01˜1.2%; at least one of Mn, Ca, Zr, Sr, and Gd with a total weight percentage of ≤3%, wherein the percentage by weight of a single element is ≤0.8%; and the balance of Mg and other inevitable impurities.

5. The high strength and corrosion-resistant magnesium alloy material of claim 4, further comprising at least one of Al, Cu, Si and Fe in a total weight percentage of ≤2%, wherein the percentage by weight of a single element is ≤0.5%.

6. The high strength and corrosion-resistant magnesium alloy material of claim 4, wherein the total amount of the inevitable impurities is less than 100 ppm.

7. The high strength and corrosion-resistant magnesium alloy material of claim 4, wherein the magnesium alloy material has a microstructure including an α-Mg phase and a column-shaped Mg.sub.2Ge intermetallic compound phase.

8. The high strength and corrosion-resistant magnesium alloy material of claim 4, wherein the magnesium alloy material has a yield strength of higher than 260 MPa, and a corrosion weight loss of less than 0.8 mg/(cm.sup.2 day).

9. A method for fabricating the high strength and corrosion-resistant magnesium alloy material of claim 1, comprising the steps of: smelting, solid solution heat treatment and extrusion, wherein in the extrusion step, the extrusion temperature is 180-350° C., the extrusion rate is 0.1-10 mm/s, and the extrusion ratio is 10:1-30:1.

10. The method for fabricating the high strength and corrosion-resistant magnesium alloy material of claim 9, wherein in the solid solution heat treatment step, the solid solution heat treatment temperature is 350-450° C., and the treatment time is 10-24 h.

11. A method for fabricating the high strength and corrosion-resistant magnesium alloy material of claim 4, comprising the steps of: smelting, solid solution heat treatment and extrusion, wherein in the extrusion step, the extrusion temperature is 180-350° C., the extrusion rate is 0.1-10 mm/s, and the extrusion ratio is 10:1-30:1.

12. The method for fabricating the high strength and corrosion-resistant magnesium alloy material of claim 11, wherein in the solid solution heat treatment step, the solid solution heat treatment temperature is 350-450° C., and the treatment time is 10-24 h.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG. 1 shows a scanning electron microscope image in backscattered electron (BSE) mode of Comparative Example 2.

[0034] FIG. 2 shows a scanning electron microscope image in backscattered electron (BSE) mode of the high strength and corrosion-resistant magnesium alloy material of Example 3.

[0035] FIG. 3 shows a scanning electron microscope image in backscattered electron (BSE) mode of the high strength and corrosion-resistant magnesium alloy material of Example 4.

[0036] FIG. 4 shows an energy spectrum analysis image of Comparative Example 2.

[0037] FIG. 5 shows an energy spectrum analysis image of the high strength and corrosion-resistant magnesium alloy material of Example 3.

[0038] FIG. 6 shows an energy spectrum analysis image of the high strength and corrosion-resistant magnesium alloy material of Example 4.

[0039] FIG. 7 shows an electron backscatter diffraction image of Comparative Example 2.

[0040] FIG. 8 shows an electron backscatter diffraction image of the high strength and corrosion-resistant magnesium alloy material of Example 3.

[0041] FIG. 9 shows an electron backscatter diffraction image of the high strength and corrosion-resistant magnesium alloy material of Example 4.

[0042] FIG. 10 shows the grain size distribution of the high strength and corrosion-resistant magnesium alloy materials of Examples 3 and 4, and Comparative Example 2.

[0043] FIG. 11 shows the potentiodynamic polarization measurement results of the high strength and corrosion-resistant magnesium alloy materials of Examples 3-4 and Comparative Examples 1-2 in a 0.1 M sodium chloride solution.

[0044] FIG. 12 shows the cathodic polarization measurement results of the high strength and corrosion-resistant magnesium alloy materials of Examples 3-4 and Comparative Examples 1-2.

[0045] FIG. 13 shows the results of weight loss and hydrogen evolution measurements of the high strength and corrosion-resistant magnesium alloy materials of Examples 3-4, Comparative Examples 1-2, and commercial AZ91 magnesium alloy.

[0046] FIG. 14 shows a scanning electron microscope image (at low magnification) in the secondary electron (SE) mode of Comparative Example 1 after immersion.

[0047] FIG. 15 shows a scanning electron microscope image (at high magnification) in the secondary electron (SE) mode of Comparative Example 1 after immersion.

[0048] FIG. 16 shows a scanning electron microscope image (at low magnification) in the secondary electron (SE) mode of Comparative Example 2 after immersion.

[0049] FIG. 17 shows a scanning electron microscope image (at high magnification) in the secondary electron (SE) mode of Comparative Example 2 after immersion.

[0050] FIG. 18 shows a scanning electron microscope image (at low magnification) in the secondary electron (SE) mode of the high strength and corrosion-resistant magnesium alloy material of Example 3 after immersion.

[0051] FIG. 19 shows a scanning electron microscope image (at high magnification) in the secondary electron (SE) mode of the high strength and corrosion-resistant magnesium alloy material of Example 3 after immersion.

[0052] FIG. 20 shows a scanning electron microscope image (at low magnification) in the secondary electron (SE) mode of the high strength and corrosion-resistant magnesium alloy material of Example 4 after immersion.

[0053] FIG. 21 shows a scanning electron microscope image (at high magnification) in the secondary electron (SE) mode of the high strength and corrosion-resistant magnesium alloy material of Example 4 after immersion.

[0054] FIG. 22 shows the cathode current density measurement results of the high strength and corrosion-resistant magnesium alloy materials of Examples 3-4 and Comparative Examples 1-2 when the anode current density is 0.025-2.5 mA/cm.sup.2.

[0055] FIG. 23 shows the cathode current density measurement results of the high strength and corrosion-resistant magnesium alloy materials of Examples 3-4 and Comparative Examples 1-2 when the anode current density is 2-24 mA/cm.sup.2.

[0056] FIG. 24 shows the anode dissolution current density of the high strength and corrosion-resistant magnesium alloy materials of Examples 3-4 and Comparative Examples 1-2 in 0.1 M sodium chloride during open circuit potential (OCP) and potentiodynamic polarization (PDP) by inductively coupled plasma optical emission spectrometer (ICP-OES).

[0057] FIG. 25 shows the relationship between the anode dissolution current density and the anode potential of the high strength and corrosion-resistant magnesium alloy materials of Examples 3-4 and Comparative Examples 1-2.

[0058] FIG. 26 shows the microhardness measurement results of the high strength and corrosion-resistant magnesium alloy materials of Examples 3-4 and Comparative Example 2.

[0059] FIG. 27 shows the engineering stress-strain curves of the high strength and corrosion-resistant magnesium alloy materials of Examples 3-4 and Comparative Example 2.

DETAILED DESCRIPTION

[0060] The embodiments of the present invention will be further described below in conjunction with the drawings and examples. However, the explanation and description are not intended to unduly limit the technical solutions of the present invention.

Examples 1-17 and Comparative Examples 1-2

[0061] Table 1-1 and Table 1-2 list the percentage by weight (wt %) of each element in Examples 1-17 and Comparative Examples 1-2.

TABLE-US-00001 TABLE 1-1 (wt %, and the balance is Mg and other inevitable impurities) Mn, Ca, Zr, Sr, and Gd No. Ge Zn Mn Ca Zr Sr Gd in total E1 0.30  1.00  0.01 0.05  — — — 0.06  E2 0.50  1.00  0.02 0.01  — — 0.01 0.04  E3 0.30  1.00  0.02 0.8  — — — 0.82  E4 0.50  1.00  0.05 0.5  — — — 0.55  E5 0.03  1.2  0.02 — 0.5  — 0.8  1.32  E6 0.21  0.05  0.8  0.2  0.5  — 0.4  1.9  E7 0.75  0.2  0.8  0.7  0.7  — 0.8  3    E8 0.86  0.5  0.02 0.2  — — — 0.22  E9 0.27  0.08  0.8  0.5  0.01 — — 1.31  E10 0.08  1.0  0.02 0.5  0.5  — — 1.02  E11 0.05  1.2  0.02 0.5  0.5  0.1  — 1.12  E12 0.52  0.2  0.1  0.8  — — — 0.9  E13 0.02  0.4  0.02 0.8  — — 0.4  1.22  E14 0.66  0.5  0.02 0.8  0.5  — — 1.32  E15 1.16  0.04  0.02 0.8  0.8  0.8  — 2.42  E16 1.06  0.4  0.02 0.8  0.8  — 0.01 1.63  E17 1.18  0.02  0.02 0.8  0.5  0.01 0.4  1.73  CE1 0.002 0.005 0.01 0.001 — — — 0.011 CE2 0.002 1    0.02 0.001 — — — 0.021

TABLE-US-00002 TABLE 1-2 (wt %, and the balance is Mg and other inevitable impurities) Al, Cu, Inevitable Si, Fe impurities in in total Micro- No. Al Cu Si Fe total (ppm) structure E1 0.011 0.001 0.02 0.004 0.036 90 α-Mg, Mg.sub.2Ge and Mg.sub.2Ca phases E2 0.011 0.001 0.02 0.004 0.036 80 α-Mg, Mg.sub.2Ge and Mg.sub.2Ca phases E3 0.011 0.001 0.02 0.005 0.037 90 α-Mg, Mg.sub.2Ge and Mg.sub.2Ca phases E4 0.011 0.001 0.02 0.004 0.036 90 α-Mg, Mg.sub.2Ge and Mg.sub.2Ca phases E5 0.007 0.002 0.02 0.004 0.033 80 α-Mg, Mg.sub.2Ge and MgZr phases E6 0.010 0.002 0.02 0.004 0.036 90 α-Mg, Mg.sub.2Ge, Mg.sub.2Ca and MgZr phases E7 0.010 0.002 0.02 0.004 0.036 60 α-Mg, Mg.sub.2Ge, Mg.sub.2Ca, MgGd and MgZr phases E8 0.010 0.002 0.02 0.005 0.037 90 α-Mg, Mg.sub.2Ge and Mg.sub.2Ca phases E9 0.007 0.002 0.02 0.004 0.033 60 α-Mg, Mg.sub.2Ge and Mg.sub.2Ca phases E10 0.012 0.002 0.02 0.004 0.038 70 α-Mg, Mg.sub.2Ge, Mg.sub.2Ca, MgZr phases E11 0.013 0.002 0.02 0.005 0.04  90 α-Mg, Mg.sub.2Ge, Mg.sub.2Ca, MgZr and Mg.sub.2Sr phases E12 0.011 0.002 0.02 0.004 0.037 60 α-Mg, Mg.sub.2Ge and Mg.sub.2Ca phases, etc. E13 0.010 0.002 0.02 0.005 0.037 90 α-Mg, Mg.sub.2Ge, Mg.sub.2Ca, and Mg.sub.2Gd phases, etc. E14 0.015 0.002 0.02 0.004 0.041 60 α-Mg, Mg.sub.2Ge, MgZr, and Mg.sub.2Ca phases, etc. E15 0.013 0.002 0.02 0.004 0.039 70 α-Mg, Mg.sub.2Ge, Mg.sub.2Ca and Mg.sub.2Sr phases E16 0.013 0.002 0.02 0.005 0.04  90 α-Mg, Mg.sub.2Ge and Mg.sub.2Ca phases E17 0.008 0.002 0.02 0.004 0.034 60 α-Mg, Mg.sub.2Ge, Mg.sub.2Ca, Mg.sub.2Gd and Mg.sub.2Sr phases CE1 0.005 0.002 0.02 0.006 0.033 70 α-Mg phase CE2 0.013 0.001 0.02 0.005 0.039 80 α-Mg, and MgZn phases

[0062] The fabrication method of Examples 1-17 and Comparative Examples 1-2 is as follows (specific process parameters are listed in Table 2):

[0063] 1) Mixing the raw materials uniformly in a steel crucible according to the ratio of elements in Table 1-1 and Table 1-2.

[0064] 2) Smelting: heating and melting the mixture in SF.sub.6 protective atmosphere, and pouring the molten magnesium alloy liquid into a preheated mold to cool.

[0065] 3) Solid solution heat treatment.

[0066] 4) Extrusion.

TABLE-US-00003 TABLE 2 Specific process parameters in the fabrication method of Examples 1-17 and Comparative Examples 1-2. Extrusion Solid solution treatment Extrusion Extrusion Temperature Time Temperature Extrusion rate No. (° C.) (h) (° C.) ratio (mm/s) E1 400 24 320 20:1 0.1 E2 400 24 340 26:1 0.9 E3 400 24 300 12:1 0.8 E4 400 24 330 16:1 0.6 E5 450 10 300 20:1 6 E6 400 10 200 25:1 8 E7 420 20 250 28:1 5 E8 400 18 2320 18:1 2 E9 420 12 250 16:1 1 E10 440 22 350 12:1 0.5 E11 380 20 320 15:1 0.2 E12 360 22 300 20:1 0.1 E13 370 20 340 18:1 10 E14 360 18 250 15:1 0.2 E15 390 16 190 20:1 0.6 E16 400 14 180 10:1 5.5 E17 420 12 350 30:1 8.0 CE1 400 24 300 12:1 0.8 CE2 400 24 330 16:1 0.6

[0067] Performance tests were conducted on the high strength and corrosion-resistant magnesium alloy materials of Examples 1-17 and Comparative Examples 1-2. Their yield strength and corrosion weight loss value in 0.1 M NaCl solution in 24 hours were measured.

[0068] The yield strength is measured by a tensile test in accordance with ASTM E-8 standard. The yield strength is the stress corresponding to 0.2% strain. The experimental platform is Instron 4505. The stretching rate is 10.sup.−3/s. The initial length of the extensometer is 10 mm. The length of the parallel part of the stretched sample is 22 mm.

[0069] The corrosion weight loss is measured according to ASTM-G1-03 standard. The sample is a cube with a side length of 5 cm. The surface of the sample is polished with a 1200 grid sandpaper, then the sample is immersed in a 0.1 M NaCl solution at 25° C. for 24 hours. After immersion, the sample surface is cleaned to remove the corrosion. The sample is weighed after drying. The results are listed in Table 3.

TABLE-US-00004 TABLE 3 Yield strength (MPa) Corrosion weight loss (mg/cm.sup.2/day) E1 285 0.72 E2 310 0.78 E3 288 0.60 E4 320 0.70 E5 328 0.69 E6 316 0.75 E7 320 0.73 E8 306 0.77 E9 270 0.78 E10 280 0.75 E11 265 0.63 E12 295 0.58 E13 279 0.68 E14 286 0.65 E15 275 0.60 E16 266 0.62 E17 265 0.72 CE1 70 10.5 CE2 255 1.8

[0070] It can be seen from Table 3 that, the high strength and corrosion-resistant magnesium alloy material of Examples 1-17 with a yield strength of higher than 260 MPa and a corrosion weight loss of less than 0.8 mg/(cm.sup.2 day) has superior mechanical properties and corrosion resistance compared to Comparative Examples 1-2. Thus, the high strength and corrosion-resistant magnesium alloy material has a wide range of application prospects.

[0071] As can be seen from FIGS. 1 to 6, the microstructure of Comparative Example 2 consists of a single α-Mg phase. In contrast, column-shaped Mg.sub.2Ge intermetallic compound phase and small amount of Mg.sub.2Ca compound are observed in the microstructure of the high strength and corrosion-resistant magnesium alloy materials of Examples 3-4

[0072] As can be seen from FIGS. 7 to 9, the electron backscatter diffraction measures the grain size of the prepared alloy. The grain structure of Comparative Example 2 has uniform size and shape, with an average grain size of 1.2 μm. A bimodal particle size distribution is observed in the high strength and corrosion-resistant magnesium alloy materials of Examples 3 and 4, and the microstructures thereof comprises column-shaped grains with an average grain size of 10-22 μm.

[0073] FIG. 10 shows the grain size distribution of the high strength and corrosion-resistant magnesium alloy materials of Examples 3-4 and Comparative Example 2, wherein Mg-1Zn represents Comparative Example 2, Mg-1Zn-0.3Ge represents Example 3, and Mg-1Zn-0.5Ge represents Example 4.

[0074] It can be seen from FIG. 10 that when the content of germanium in the alloy increases from about 0.3% to about 0.5%, the proportion of column-shaped grains with large size increases significantly, which indicates that the content of germanium in the alloy can affect the formation of column-shaped grains with large size.

[0075] In order to reveal the influence of the addition of alloying elements on the electrochemical performances of the magnesium alloy, potentiodynamic polarization measurement and cathode polarization measurement are conducted on Comparative Examples 1-2 and the high strength and corrosion-resistant magnesium alloy materials of Examples 3-4. The specific results are shown in FIGS. 11 and 12, wherein Mg represents Comparative Example 1 (where the trace amounts of Ge and Zn can be ignored), Mg-1Zn represents Comparative Example 2, Mg-1Zn-0.3Ge represents Example 3, and Mg-1Zn-0.5Ge represents Example 4.

[0076] As can be seen from FIG. 11, due to the increase of Zn content, the corrosion potential of the high strength and corrosion-resistant magnesium alloy material of Comparative Example 2 increases by about 50 mV compared with Comparative Example 1. In addition, due to the increase of germanium content, the corrosion potentials of the high strength and corrosion-resistant magnesium alloy materials of Examples 3 and 4 is reduced to about −1.67 V.sub.SCE.

[0077] As can be seen from FIG. 12, the cathode reaction rate of Comparative Example 2 is higher than that of Comparative Example 1, indicating that the increase of Zn improves the cathode kinetics. On the contrary, the increase of Ge leads to a decrease in the cathode current density of the high strength and corrosion-resistant magnesium alloy materials of Example 3 and Example 4, indicating that Ge alloying offsets the effect of Zn alloying and significantly reduces the potential dynamics of the cathode.

[0078] By incorporating FIG. 11 and FIG. 12, it can be seen that the high strength and corrosion-resistant magnesium alloy materials of Example 3 and Example 4 show an anode kinetics similar to that of Comparative Example 1. The change of corrosion potential of Example 3 and Example 4 are mainly due to the change of cathode kinetics.

[0079] In order to verify the long-term corrosion performance of magnesium alloys, long-term (24 h) immersion test is conducted on Comparative Examples 1-2 and Examples 3-4 and commercial AZ91 magnesium alloy at open circuit potential in a 0.1 M sodium chloride solution. The results are shown in FIG. 13, wherein Mg represents Comparative Example 1, AZ91 represents commercial AZ91 magnesium alloy, Mg-1Zn represents Comparative Example 2, Mg-1Zn-0.3Ge represents Example 3, and Mg-1Zn-0.5Ge represents Example 4 in the x-coordinate.

[0080] As can be seen from FIG. 13, under the conditions of immersion test, the weight loss and hydrogen evolution rate of the high strength and corrosion-resistant magnesium alloy materials of Example 3 and Example 4 are about an order of magnitude smaller than those of Comparative Example 1 and commercial AZ91 magnesium alloy, which proves that the addition of Zn and Ge can reduce the corrosion rate of Mg.

[0081] After long-term (24 h) immersion test of Comparative Examples 1-2 and Examples 3-4 at open circuit potential in a 0.1 M sodium chloride solution, the corrosion products were washed with a chromic acid solution (i.e., 200 g/L chromium trioxide, 10 g/L silver nitrate and 20 g/L barium nitrate) to show the degree of corrosion, and then the surface morphology was observed.

[0082] As can be seen from FIGS. 14 to 21, after the immersion test, the corrosion morphology of the high strength and corrosion-resistant magnesium alloy materials of Examples 3 and 4 are different from that of Comparative Example 1 and Comparative Example 2. Discrete surface corrosion sites were observed in Example 3 and Example 4, while widespread “filamentous” corrosion was observed in Comparative Example 1 and Comparative Example 2. Thus, Zn and Ge enhance the anti-corrosion ability of magnesium alloys and inhibit the rate of cathode reaction (i.e., hydrogen evolution reaction).

[0083] The influence of alloying on cathode activation (difference effect) of magnesium is further evaluated by constant current potential experiment. As shown in FIG. 22, the sample is anodic polarized in a gradual increment of 0.025-2.5 mA/cm.sup.2 cycle, and a fixed negative potential (−2 V.sub.SCE) is kept in each anodic polarization period to measure the cathode current density maintained on the anodic polarized surface (i.e., applied dissolution current density). As shown in FIG. 23, the sample is anodic polarized in a gradual increment of 2-24 mA/cm.sup.2 cycle, and a fixed negative potential (−2 V.sub.SCE) is kept in each anodic polarization period to measure the cathode current density maintained on the anodic polarized surface (i.e., applied dissolution current density). In FIG. 22 and FIG. 23, Mg represents Comparative Example 1, Mg-1Zn represents Comparative Example 2, Mg-1Zn-0.3Ge represents Example 3, and Mg-1Zn-0.5Ge represents Example 4.

[0084] As can be seen from FIG. 22, the cathode current density measured in Example 3 and Example 4 are 2-3 times lower than those of Comparative Example 1 and Comparative Example 2, indicating that the addition of Ge inhibits the activation of magnesium cathode.

[0085] As can be seen from FIG. 23, a similar trend can be observed when the experiment is repeated with a higher anode polarization current density (2-24 mA/cm.sup.2). Thus, the high strength and corrosion-resistant magnesium alloy materials of Example 3 and Example 4 show the potential as fine electrode materials due to their good corrosion resistance performance, low self-reaction (corrosion) rate, and little hydrogen evolution.

[0086] FIG. 24 shows the anode dissolution current density of the high strength and corrosion-resistant magnesium alloy materials of Examples 3-4 and Comparative Examples 1-2 in 0.1 M sodium chloride during open circuit potential (OCP) and potentiodynamic polarization (PDP) by inductively coupled plasma optical emission spectrometer (ICP-OES), wherein Mg represents Comparative Example 1, Mg-1Zn represents Comparative Example 2, Mg-1Zn-0.3Ge represents Example 3, and Mg-1Zn-0.5Ge represents Example 4.

[0087] It can be seen from FIG. 24 that Example 3 and Example 4 exhibit the lowest anode dissolution current density during both OCP and potentiodynamic polarization.

[0088] FIG. 25 shows the relationship between the anode dissolution current density and the anode potential of the high strength and corrosion-resistant magnesium alloy materials of Examples 3-4 and Comparative Examples 1-2, wherein Mg represents Comparative Example 1, Mg-1Zn represents Comparative Example 2, Mg-1Zn-0.3Ge represents Example 3, and Mg-1Zn-0.5 Ge represents Example 4.

[0089] As can be seen from FIG. 25, for Comparative Examples 1-2 and Examples 3-4, the anode dissolution current density increases logarithmically as the anode potential increases. It shall be noted that the kinetics of the anode reaction of Examples 3-4 is lower than those of Comparative Examples 1-2. The slopes of curves derived from ICP-OES polarization analysis are listed in Table 4.

TABLE-US-00005 TABLE 4 No. Slope (V/μA .Math. cm.sup.2) E3 0.0168 E4 0.0234 CE1 0.0114 CE2 0.0106

[0090] It can be seen from Table 4 that the addition of small amount of the above-mentioned alloying elements inhibits the kinetics of the magnesium anode.

[0091] FIG. 26 shows the microhardness measurement results of Comparative Example 2 and Examples 3-4. FIG. 27 shows the engineering stress-strain curves of Comparative Example 2 and Examples 3-4. In FIG. 26 and FIG. 27, Mg-1Zn represents Comparative Example 2, Mg-1Zn-0.3Ge represents Example 3, and Mg-1Zn-0.5Ge represents Example 4.

[0092] It can be seen from FIG. 26 that as the Ge content increases, the hardness of the alloy increases from 50HV1 in Comparative Example 2 to 83HV1 in Example 4.

[0093] It can be seen from FIG. 27 that as the Ge content increases, the yield strength of the alloy increases from about 255 MPa in Comparative Example 2 to about 320 MPa in Example 4.

[0094] It should be noted that the portion of prior art in the protection scope of the present invention is not limited to the embodiments given herein. All prior art that does not contradict the solutions of the present invention, including but not limited to the previous patent documents, prior publications, prior applications, etc., can all be included in the protection scope of the present invention.

[0095] In addition, the combination of the technical features in the present disclosure is not limited to the combination described in the claims or the combination described in the specific examples. All technical features described herein can be freely combined in any way, unless contradicts between each other.

[0096] It should also be noted that the above-listed embodiments are only specific examples of the present invention. Obviously, the present invention should not be unduly limited to such specific embodiments. Changes or modifications that can be directly or easily derived from the present disclosure by those skilled in the art are intended to be within the protection scope of the present invention.