Heat-resistant and soluble magnesium alloy, preparation method and use thereof

Abstract

A heat-resistant and soluble magnesium alloy, and a preparation method having an elemental composition at the following atomic percentage: Lu 0.10% to 8.00%, Ce 0.001 to 0.05%, Al 0.10% to 0.60%, Ca 0.001% to 0.50%, Cu 0.01% to 1.00%, Ni 0.01% to 1.00%, impurity elements <0.30%, and the rest is Mg, and formed in magnesium alloys are high temperature phase of Lu.sub.5Mg.sub.24, Mg.sub.2Cu, Mg.sub.2Ni, Mg.sub.12Ce, Al.sub.11Ce.sub.3 and (Mg, Al).sub.2Ca, and Long Period Stacking Ordered (LPSO) phases as Mg—Lu—Al and Mg—Ce—Al. The magnesium alloy has good mechanical performances at 150° C., and a dissolution rate of 30 to 100 mg.Math.cm.sup.−2h−1 in a 3% KCl solution at 93° C.

Claims

1. A heat-resistant and soluble magnesium alloy, having a composition at the following atomic percentage: Lu 0.10% to 8.00%, Ce 0.001 to 0.05%, Al 0.10% to 0.60%, Ca 0.001% to 0.50%, Cu 0.01% to 1.00%, Ni 0.01% to 1.00%, impurity elements <0.30%, and the rest is Mg; wherein the magnesium alloy comprises high temperature phases of Lu.sub.5Mg.sub.24, Mg.sub.2Cu, Mg.sub.2Ni, Mg.sub.12Ce, Al.sub.11Ce.sub.3 and (Mg, Al).sub.2Ca, and long period stacking ordered (LPSO) phases of Mg—Lu—Al and Mg—Ce—Al.

2. The magnesium alloy according to claim 1, having a composition at the following atomic percentage: Lu 0.10% to 4.00%, Ce 0.001 to 0.04%, Al 0.20% to 0.50%, Ca 0.10% to 0.40%, Cu 0.10% to 0.50%, Ni 0.10% to 0.50%, impurity elements <0.30%, and the rest is Mg.

3. The magnesium alloy according to claim 1, having a composition at the following atomic percentage: Lu 0.50%, Ce 0.02%, Al 0.20%, Ca 0.10%, Cu 0.20%, Ni 0.10%, impurity elements <0.20%, and the rest is Mg.

4. The magnesium alloy according to claim 1, having a composition at the following atomic percentage: Lu 4.0%, Ce 0.04%, Al 0.50%, Ca 0.50%, Cu 0.40%, Ni 0.20%, impurity elements <0.20%, and the rest is Mg.

5. A method for preparing the magnesium alloy according to claim 1, the method comprising: mixing raw materials of the magnesium alloy, to obtain a mixture; melting at 720 to 760° C. and refining the mixture to obtain a melt; casting the melt to obtain an ingot at 680 to 700° C.; homogenizing the ingot to obtain a billet; plastically processing the billet to obtain a shaped part; and subjecting the shaped part to an aging strengthening treatment, thereby obtaining the magnesium alloy.

6. The method according to claim 5, wherein the raw materials comprise magnesium, aluminum, a Mg—Lu master alloy, a Mg—Ce master alloy, a Mg—Ca master alloy, a Mg—Cu master alloy and a Mg—Ni master alloy.

7. The method according to claim 5, wherein, in the refining process, a refining agent is added or an inert protective gas is introduced in a refining furnace.

8. The method according to claim 5, further comprising: carrying out a solid solution treatment, wherein: the solid solution treatment comprises steps that the ingot is sequentially heated, maintained at a temperature and cooled; the ingot is heated to a temperature of 480 to 540° C. for 2 to 24 h; and an air cooling is employed.

9. The method according to claim 5, wherein the plastically processing comprises extruding, rolling or forging.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The accompanying drawings, which constitute a part of the present invention, are used to provide further understanding of the present application. The exemplary examples of the present invention and the descriptions thereof are used to explain the present invention, and do not constitute an improper limitation on the present invention.

(2) FIG. 1 is a SEM image of microstructure of the magnesium alloy from Example 1;

(3) FIGS. 2(a) and 2(b) are TEM images of microstructure of the magnesium alloy from Example 1, and the LPSO phases are: (a) Mg—Lu—Al and (b) Mg—Ce—Al phases.

(4) FIG. 3 is a metallographic diagram of microstructure of the magnesium alloy from Comparative example 2.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(5) It should be noted that the following detailed descriptions are all exemplary and are intended to provide further explanation of the present invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

(6) It should be noted that the terminology used herein is only for describing a specific embodiment, and is not intended to limit the exemplary embodiments according to the present application. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise, and it should also be understood that when the terms “including” and/or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components, and/or combinations thereof. It is further described the present invention below in conjunction with Examples.

Example 1

(7) The heat-resistant and soluble magnesium alloy described in this Example is a material having a high elongation and a slow dissolving rate, which has an elemental composition at the following atomic percentage: Lu 0.40%, Ce 0.04%, Al 0.20%, Ca 0.01%, Cu 0.10%, Ni 0.05%, impurity elements <0.30%, and the rest is Mg.

(8) The heat-resistant and soluble alloy in this Example is prepared by a method comprising steps of:

(9) (1) the raw materials were weighted according to the above amount ratio, the raw materials used were a pure magnesium ingot, a pure aluminum ingot, Mg—Lu master alloy, a Mg—Ce master alloy, a Mg—Ca master alloy, a Mg—Cu master alloy, a Mg—Ni master alloy.

(10) (2) under protection of a mixed gas of CO.sub.2 and SF.sub.6 at a volume ratio of 200:1, the raw materials were melt at 720° C., maintained at the temperature for 60 min, stirred for 10 min, and refined for 20 min, after the refining the temperature is raised to 780° C., allowed to stand still for 40 min, and cast into a semi-continuous ingot at 680° C.

(11) (3) the above ingot was subjected to a homogenization, at 480° C. for 4 h; cooled by an air cooling; then cut into corresponding billet, which was then peeled.

(12) (4) the billet was extruded into a bar through an extruder under the conditions of an extrusion temperature of 400° C., an extrusion ratio of 8, and an extrusion speed of 1 m/min.

(13) (5) the above bar was subjected to an aging strengthening treatment at an aging strengthening treatment temperature of 170° C. for 24 hours, and the strength was further improved to obtain the heat-resistant and soluble alloy having a high elongation in this Example.

(14) It can be seen from FIG. 1 that the microstructure of the magnesium alloy contains high-temperature phases of Lu.sub.5Mg.sub.24, Mg.sub.2Cu, Mg.sub.2Ni. From the TEM image of FIG. 2, it can be found that a LPSO phase, Mg—Lu—Al and Mg—Ce—Al phases, was formed in the microstructure of the magnesium alloy.

Example 2

(15) The heat-resistant and soluble magnesium alloy described in this Example is a material having a high elongation and a slow dissolving rate, which has an elemental composition at the following atomic percentage: Lu 0.10%, Ce 0.001%, Al 0.10%, Ca 0.001%, Cu 0.01%, Ni 0.01%, impurity elements <0.30%, and the rest is Mg.

(16) The heat-resistant and soluble alloy in this Example is prepared by a method comprising steps of:

(17) (1) the raw materials were weighted according to the above amount ratio, the raw materials used were a pure magnesium ingot, a pure aluminum ingot, Mg—Lu master alloy, a Mg—Ce master alloy, a Mg—Ca master alloy, a Mg—Cu master alloy, a Mg—Ni master alloy.

(18) (2) under protection of a mixed gas of CO.sub.2 and SF.sub.6 at a volume ratio of 200:1, the raw materials were melt at 720° C., maintained at the temperature for 50 min, stirred for 10 min, and refined for 30 min, after the refining the temperature is raised to 780° C., allowed to stand still for 30 min, and cast into a semi-continuous ingot at 680° C.

(19) (3) the above ingot was subjected to a homogenization, at 480° C. for 2 h; cooled by an air cooling; then cut into corresponding billet, which was then peeled.

(20) (4) the above billet was extruded into a bar through an extruder under the conditions of an extrusion temperature of 400° C., an extrusion ratio of 20, and an extrusion speed of 0.5 m/min.

(21) (5) the above bar was subjected to an aging strengthening treatment at an aging strengthening treatment temperature of 160° C. for 36 hours, and the strength was further improved to obtain the heat-resistant and soluble alloy having a high elongation in this Example.

Example 3

(22) The heat-resistant and soluble magnesium alloy described in this Example is a material having a high-strength and a fast dissolving rate, which has an elemental composition at the following atomic percentage: Lu 8.00%, Ce 0.05%, Al 0.60%, Ca 0.50%, Cu 1.00%, Ni 1.00%, impurity elements <0.30%, and the rest is Mg.

(23) The heat-resistant and soluble alloy in this Example is prepared by a method comprising steps of:

(24) (1) The raw materials were weighted according to the above amount ratio, the raw materials used were a pure magnesium ingot, a pure aluminum ingot, Mg—Lu master alloy, a Mg—Ce master alloy, a Mg—Ca master alloy, a Mg—Cu master alloy, a Mg—Ni master alloy.

(25) (2) Under protection of a mixed gas of CO.sub.2 and SF.sub.6 at a volume ratio of 400:1, the raw materials were melt at 760° C., maintained at the temperature for 60 min, stirred for 20 min, and refined for 20 min, after the refining the temperature is raised to 800° C., allowed to stand still for 30 min, and cast into a semi-continuous ingot at 700° C.

(26) (3) The above ingot was subjected to a homogenization, at 540° C. for 16 h; cooled by an air cooling; then cut into corresponding billet, which was then peeled.

(27) (4) The above billet was extruded into a bar through an extruder under the conditions of an extrusion temperature of 450° C., an extrusion ratio of 8, and an extrusion speed of 0.5 m/min.

(28) (5) The above bar was subjected to an aging strengthening treatment at an aging strengthening treatment temperature of 200° C. for 48 hours, and the strength was further improved to obtain the heat-resistant and soluble alloy having a high strength in this Example.

Example 4

(29) The heat-resistant and soluble magnesium alloy described in this Example is a material having a high-strength and a fast dissolving rate, which has an elemental composition at the following atomic percentage: Lu 4.00%, Ce 0.03%, Al 0.20%, Ca 0.20%, Cu 0.80%, Ni 0.80%, impurity elements <0.30%, and the rest is Mg.

(30) The heat-resistant and soluble alloy in this Example is prepared by a method comprising steps of:

(31) (1) The raw materials were weighted according to the above amount ratio, the raw materials used were a pure magnesium ingot, a pure aluminum ingot, Mg—Lu master alloy, a Mg—Ce master alloy, a Mg—Ca master alloy, a Mg—Cu master alloy, a Mg—Ni master alloy.

(32) (2) Under protection of a mixed gas of CO.sub.2 and SF.sub.6 at a volume ratio of 400:1, the raw materials were melt at 760° C., maintained at the temperature for 50 min, stirred for 15 min, and refined for 30 min, after the refining the temperature is raised to 800° C., allowed to stand still for 35 min, and cast into a semi-continuous ingot at 700° C.

(33) (3) The above ingot was subjected to a homogenization, at 540° C. for 12 h; cooled by an air cooling; then cut into corresponding billet, which was then peeled.

(34) (4) The above billet was extruded into a bar through an extruder under the conditions of an extrusion temperature of 450° C., an extrusion ratio of 10, and an extrusion speed of 0.5 m/min.

(35) (5) The above bar was subjected to an aging strengthening treatment at an aging strengthening treatment temperature of 180° C. for 96 hours, and the strength was further improved to obtain the heat-resistant and soluble alloy having a high strength in this Example.

Example 5

(36) The heat-resistant and soluble magnesium alloy described in this Example is a material having a high-strength and a fast dissolving rate, which has an elemental composition at the following atomic percentage: Lu 3.50%, Ce 0.03%, Al 0.40%, Ca 0.40%, Cu 0.20%, Ni 0.60%, impurity elements <0.30%, and the rest is Mg.

(37) The heat-resistant and soluble magnesium alloy described in this Example was prepared in a method same as that in Example 4.

Comparative Example 1

(38) The comparative alloy is an as-cast AZ91D magnesium alloy, and this alloy has a chemical composition of: Mg-9.0 wt %, Al-0.80 wt %, Zn-0.3 wt %, Mn-0.025 wt % Cu. The raw material of alloy (raw material comprises: a pure magnesium ingot, a pure aluminum ingot, a pure zinc ingot, a Mg—Mn master alloy, a Mg—Cu master alloy), under protection of a mixed gas of CO.sub.2 and SF.sub.6 (a volume ratio of 100:1), the raw materials were melt at 720° C., maintained at the temperature for 60 min, stirred for 5 min, and refined for 20 min, after the refining the temperature is raised to 760° C., allowed to stand still for 40 min, and cast into a ingot at 700° C.

Comparative Example 2

(39) It is similar to Example 1 except that, the magnesium alloy of this Comparative example has an elemental composition at the following atomic percentage: Ce 0.04%, Al 0.20%, Ca 0.01%, Cu 0.10%, Ni 0.05%, impurity elements <0.30%, and the rest is Mg.

(40) The heat-resistant and soluble magnesium alloy described in this Example was prepared in a method same as that in Example 1.

(41) It can be seen from FIG. 3 that the microstructure of the obtained magnesium alloy has no Lu.sub.5Mg.sub.24 a high temperature phase therein, therefore has a high temperature performance lower than Example 1.

Comparative Example 3

(42) It is similar to Example 1 except that the magnesium alloy of this Comparative example has an elemental composition at the following atomic percentage: Lu 0.40%, Cu 0.10%, Ni 0.05%, impurity elements <0.30%, and the rest is Mg.

(43) The heat-resistant and soluble magnesium alloy described in this Example was prepared in a method same as that in Example 1.

Comparative Example 4

(44) It is similar to Example 1 except that the magnesium alloy of this Comparative example has an elemental composition at the following atomic percentage: Lu 0.40%, Ce 0.04%, Al 2.20%, Ca 1.0%, Cu 0.10%, Ni 0.05%, impurity elements <0.30%, and the rest is Mg.

(45) The heat-resistant and soluble magnesium alloy described in this Example was prepared in a method same as that in Example 1.

Comparative Example 5

(46) It is similar to Example 3 except that the magnesium alloy of this Comparative example has an elemental composition at the following atomic percentage: Lu 9.0%, Ce 0.2%, Al 2.0%, Ca 0.40%, Cu 1.20%, Ni 1.10%, impurity elements <0.30%, and the rest is Mg.

(47) The heat-resistant and soluble magnesium alloy described in this Example was prepared in a method same as that in Example 3.

Comparative Example 6

(48) It is similar to Example 4 except that the magnesium alloy of this Comparative example has an elemental composition at the following atomic percentage: Lu 4.0%, Ce 0.03%, Al 2.0%, Ca 0.40%, Cu 0.20%, Ni 0.60%, impurity elements <0.30%, and the rest is Mg.

(49) The heat-resistant and soluble magnesium alloy described in this Example was prepared in a method same as that in Example 4.

Comparative Example 7

(50) It is similar to Example 4 except that the magnesium alloy of this Comparative example has an elemental composition at the following atomic percentage: Lu 9.0%, Ca 0.40%, Cu 0.20%, Ni 0.60%, impurity elements <0.30%, and the rest is Mg.

(51) The heat-resistant and soluble magnesium alloy described in this Example was prepared in a method same as that in Example 4.

Comparative Example 8

(52) The magnesium alloy in this Comparative example has an element composition same as that of Example 1, but a different preparation method. In the process of the preparation of magnesium alloy in this Comparative example, the obtained ingot was not subjected to a homogenization.

Comparative Example 9

(53) The magnesium alloy in this Comparative example has an element composition same as that of Example 1, but a different preparation method. In the process of the preparation of magnesium alloy in this Comparative example, the above billet was extruded into a bar under the conditions of an extrusion temperature of 450° C., an extrusion ratio of 10, and an extrusion speed of 40 m/min.

Comparative Example 10

(54) The magnesium alloy in this Comparative example has an element composition same as that of Example 4, but a different preparation method. In the process of the preparation of the magnesium alloy in this Comparative example, the obtained bar was not subjected to an aging strengthening treatment.

(55) The heat-resisting soluble magnesium alloy of the above examples and the magnesium alloy of the comparative examples were subjected to grain size statistics, a mechanical performance test, and a dissolution performance test. The grain size statistical method was performed according to GBT6394-2002, a room temperature tensile mechanical performance test method was performed according to GB T 228.1-2010, a high temperature tensile mechanical performance test method was performed according to GB T 228.2-2015, and the dissolution performance test was performed under conditions of: a φ20 mm×20 mm sample was placed in a 3% KCl aqueous solution at a temperature of 93° C., and the weight dissolved per hour was tested. The dissolution rate was: weight of dissolution/(sample surface area ×duration). The relevant results are shown in Table 1.

(56) TABLE-US-00001 TABLE 1 Grain size, room temperature mechanical performances, high temperature mechanical performances, and high temperature dissolution rate of magnesium alloy Dissolution Room temperature Mechanical Yield rate in mechanical performances performances at 150° C. Strength(at solution Tensile Yield Tensile Yield 150° C.)/ of 3% KCl Average strength/ Strength/ strength/ Strength/ (RT Yield at 93° C./ Grain MPa MPa Elongation MPa MPa Elongation Strength) × 100% mg .Math. cm.sup.−2 h.sup.−1 Size/μm Example 1 215 140 28% 210 135 30% 96.4% 46 8 2 206 120 29% 202 116 30% 96.7% 32 9 3 425 401 16% 422 402 17% 100.2% 98 23 4 384 323 18% 382 325 19% 100.6% 89 25 5 378 327 18% 376 330 20% 100.9% 85 32 Comparative 1 260 193  6% 220 162  7% 83.9% 0.2 42 example 2 196 114 19% 165 95 19% 83.3% 37 15 3 206 116 18% 172 93 19% 80.2% 43 18 4 278 155  9% 235 130  8% 83.9% 44 25 5 409 364 12% 347 294 11% 80.8% 92 34 6 345 283 11% 284 223 10% 78.8% 82 36 7 357 294 10% 296 227  9% 77.2% 79 37 8 208 127 18% 195 108 18% 85.0% 36 28 9 194 93 12% 170 82 11% 88.2% 34 54 10 327 285 19% 293 228 19% 80.0% 85 25

(57) It can be seen from the results of the mechanical performance test that the heat-resistant and soluble magnesium alloy prepared by the present invention has good mechanical performances at 150° C.: its tensile yield strength at 150° C. exceeds 90% of its tensile yield strength at room temperature, and its elongation at 150° C. exceeds its elongation at room temperature. The dissolution rate in a 3% KCl solution at 93° C. is 30-100 mg.Math.cm.sup.−2h.sup.−1.

(58) Compared with the magnesium alloy of Comparative Example 1, the heat-resistant and soluble magnesium alloy of the present invention has a dissolution rate significantly higher than that of the magnesium alloy of Comparative Example 1.

(59) The magnesium alloys of Comparative Examples 2, 3, and 4 were prepared in same preparation method as that of Example 1, but their element contents of Lu, Ce, Al, and Ca are not within the content range of the present invention, and therefore their high-temperature mechanical performances are significantly lower than room-temperature performances.

(60) The magnesium alloys of Comparative Examples 5, 6, and 7 were prepared in same preparation method as those of Examples 3 and 4, but their elemental contents of Ce, Al, and Ca are not within the content range of the present invention, and therefore their high-temperature mechanical performances are also significantly lower than room-temperature performances.

(61) The magnesium alloys of Comparative Examples 8, 9, and 10 have same components as those of Examples 1 and 4, respectively, but their preparation processes are different from the requirements of the present invention, and therefore their high-temperature mechanical performances are also significantly lower than room-temperature performances.

(62) The above descriptions are only preferred examples of the present invention, and not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.