A method for preparing magnesium-yttrium alloy

Abstract

The present invention provides a method for preparing a magnesium-containing yttrium-containing alloy, and relates to the technical field of alloys. The present invention provides a method for preparing a magnesium-containing yttrium-containing alloy, comprising: weighing raw materials according to the proportion of each metal element in the magnesium-containing yttrium-containing alloy, wherein the raw material corresponding to the Mg element is a magnesium alloy; performing vacuum induction melting on other metal materials except the magnesium alloy to obtain a first melt; introducing an inert gas to a pressure of 0.01-0.05 MPa, mixing the magnesium alloy and the first melt, performing positive pressure induction melting to obtain a second melt; casting the second melt to obtain an ingot; performing rotary annealing on the ingot to obtain the magnesium-containing yttrium-containing alloy. The present invention adopts secondary feeding, uses magnesium alloy as raw material, adopts a positive pressure atmosphere during the smelting process, and uses a rotary annealing furnace during annealing to reduce the smelting time of the magnesium alloy, thereby reducing the volatilization of magnesium.

Description

Technical Field

[0001] The invention belongs to the technical field of alloys, and in particular relates to a method for preparing a magnesium- and yttrium-containing alloy. Background Art

[0002] Hydrogen storage materials are a type of functional material with high hydrogen storage density discovered in the late 1960s. The most widely used material is LaNi5 alloy, which is mainly used as the negative electrode material of nickel-hydrogen batteries (MH / Ni). Its theoretical electrochemical capacity is 373mAh·g -1 The maximum capacity of commercial negative electrode materials Mm (NiCoMnA1)5 (where Mm is a mixed rare earth metal) in actual use is about 350 mAh g -1 In order to develop alloys with better electrochemical performance or larger quantities, the research on rare earth-magnesium-nickel alloys and rare earth-yttrium-nickel alloys has become a hot topic. The theoretical electrochemical capacity of rare earth-magnesium-nickel and rare earth-yttrium-nickel alloys is high, especially rare earth-magnesium-nickel AB3 type, A2B7 type, A5B 19 Type alloy.

[0003] The melting point and boiling point of metallic magnesium are 648.8°C and 1107°C respectively. In conventional alloy smelting methods, magnesium basically evaporates completely under a certain pressure and temperature, and only a trace amount of Mg exists in the melt, making it impossible to obtain an alloy with the required composition. At the same time, the volatilized magnesium condenses in the furnace cavity of the smelting furnace to form fine magnesium powder, which is flammable and explosive when exposed to air when the furnace is opened, posing a safety hazard. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a method for preparing a magnesium-containing yttrium-containing alloy. The method provided by the present invention can reduce the volatilization of magnesium, ensure the accuracy of the alloy formula, improve product quality and have a high safety factor.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing a magnesium-containing yttrium-containing alloy, comprising the following steps:

[0007] Weigh raw materials according to the ratio of each metal element in the magnesium-containing and yttrium-containing alloy, wherein the raw material corresponding to the Mg element is a magnesium alloy;

[0008] performing vacuum induction melting on raw materials other than the magnesium alloy to obtain a first melt;

[0009] Introducing an inert gas to a pressure of 0.01-0.05 MPa, mixing the magnesium alloy and the first melt, and performing positive pressure induction melting to obtain a second melt;

[0010] Casting the second melt to obtain an ingot;

[0011] The ingot is subjected to rotation annealing to obtain the magnesium- and yttrium-containing alloy.

[0012] Preferably, the temperature of the rotary annealing is 700-1200° C., and the time is 6-15 hours.

[0013] Preferably, the atmosphere pressure of the rotary annealing is 0.01-0.05 MPa.

[0014] Preferably, the spin annealing is performed in an inert gas.

[0015] Preferably, the magnesium- and yttrium-containing alloy includes La.

[0016] Preferably, the magnesium- and yttrium-containing alloy further includes at least two of Ni, Al, Co, Nb and Mn.

[0017] Preferably, vacuum induction melting of the raw materials other than the magnesium alloy comprises:

[0018] The raw materials other than the magnesium alloy are placed in a vacuum induction furnace, the vacuum induction furnace is evacuated, preheated and degassed, and then inert gas is introduced until the vacuum degree is -0.06~-0.01MPa, and the power of the power supply is adjusted to 10~20kW to melt all the materials.

[0019] Preferably, the power of the power supply during the positive pressure induction melting is 10-20 kW.

[0020] Preferably, before mixing the magnesium alloy and the first melt, the power of the power supply is first reduced to 3-5 kW, and the inert gas is continuously introduced to increase the pressure to the pressure of positive pressure induction melting, and after the surface of the first melt peels off, the magnesium alloy and the first melt are mixed.

[0021] Preferably, the power supply is a medium frequency power supply.

[0022] The invention provides a method for preparing a magnesium-containing and yttrium-containing alloy, comprising the following steps: weighing raw materials according to the proportion of each metal element in the magnesium-containing and yttrium-containing alloy, wherein the raw material corresponding to the Mg element is a magnesium alloy; performing vacuum induction melting on raw materials other than the magnesium alloy to obtain a first melt; introducing an inert gas to a pressure of 0.01-0.05 MPa, mixing the magnesium alloy and the first melt, performing positive pressure induction melting, and obtaining a second melt; casting the second melt to obtain an ingot; and performing rotary annealing on the ingot to obtain the magnesium-containing and yttrium-containing alloy. The present invention first melts the raw materials other than the magnesium alloy, and finally melts the magnesium alloy, which can reduce the melting time of the magnesium alloy and further reduce the volatilization of magnesium; the magnesium alloy is used as the raw material instead of pure metal magnesium, and a positive pressure atmosphere is used in the melting process, which can increase the melting and boiling points of the magnesium alloy, thereby reducing the volatilization of magnesium and ensuring the accuracy of the alloy formula; rotary annealing is used in the annealing process so that the temperature inside the alloy can be balanced, a more uniform internal structure can be obtained, the annealing efficiency can be improved, and the volatilization of magnesium can be reduced.

[0023] The test results show that the magnesium-containing and yttrium-containing alloy prepared by the method provided by the present invention has a final measured Mg content that differs by 0.01% from the initially set Mg content, which effectively reduces the volatilization of magnesium, ensures the accuracy of the alloy formula, and improves product quality. At the same time, the magnesium-containing and yttrium-containing alloy prepared by the present invention has good electrochemical properties and capabilities, and the maximum discharge capacity of 1C is 359~371mAh·g -1 The hydrogen absorption capacity is 1.30~1.38wt%, the hydrogen absorption pressure is 0.090~0.1MPa, and the hydrogen release pressure is 0.045~0.055MPa. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0025] Figure 1 This is the XRD pattern of the magnesium- and yttrium-containing alloy prepared in Example 1. DETAILED DESCRIPTION

[0026] The present invention provides a method for preparing a magnesium-containing yttrium-containing alloy, comprising the following steps:

[0027] Weigh raw materials according to the ratio of each metal element in the magnesium-containing and yttrium-containing alloy, wherein the raw material corresponding to the Mg element is a magnesium alloy;

[0028] performing vacuum induction melting on raw materials other than the magnesium alloy to obtain a first melt;

[0029] Introducing an inert gas to a pressure of 0.01-0.05 MPa, mixing the magnesium alloy and the first melt, and performing positive pressure induction melting to obtain a second melt;

[0030] Casting the second melt to obtain an ingot;

[0031] The ingot is subjected to rotation annealing to obtain the magnesium- and yttrium-containing alloy.

[0032] In the present invention, unless otherwise specified, the raw materials involved are commercially available products well known in the art.

[0033] In the present invention, the vacuum induction melting, positive pressure induction melting and casting are preferably performed in a vacuum induction melting furnace.

[0034] The present invention weighs raw materials according to the ratio of each metal element in the magnesium-containing and yttrium-containing alloy, wherein the raw material corresponding to the Mg element is a magnesium alloy; vacuum induction melting is performed on the raw materials other than the magnesium alloy to obtain a first melt.

[0035] In the present invention, the magnesium-containing and yttrium-containing alloy preferably includes La. Further, the magnesium-containing and yttrium-containing alloy preferably also includes at least two of Ni, Al, Co, Nb and Mn. In a specific embodiment, the magnesium-containing and yttrium-containing alloy may include NiAl, NiAlCo, NiAlNb, NiAlMn, NiCoAlNb or NiAlCoMn in addition to Mg, Y and La.

[0036] In the present invention, the chemical formula of the magnesium-containing and yttrium-containing alloy is preferably La 0.8-x Y 0.20 Mg x M y , wherein M is at least two of Ni, Co, Al, Nb and Mn, 0.23≤x≤0.26, 3.34≤y≤3.55, x is the molar amount of Mg, and in a specific embodiment, x may be 0.23, 0.24, 0.25 or 0.26; y is the molar amount of element M, and in a specific embodiment, y may be 3.34, 3.38, 3.42, 3.46, 3.48, 3.50, 3.52 or 3.55.

[0037] In the present invention, the chemical formula of the magnesium-containing and yttrium-containing alloy is preferably La 0.8-x Y 0.20 Mg x (NiAl) y ,La 0.8- x Y 0.20 Mg x (NiCoAl) y ,La0.8-x Y 0.20 Mg x (NiMnAl) y ,La 0.8-x Y 0.20 Mg x (NiNbAl) y ,La 0.8-x Y 0.20 Mg x (NiCoAlNb) y or La 0.8-x Y 0.20 Mg x (NiCoAlMn) y .

[0038] The present invention has no special requirements for the types of raw materials corresponding to elements other than Mg, and raw materials well known in the art can be used. For example, other raw materials can be selected from metal lanthanum, yttrium alloy, metal nickel, metal aluminum, metal cobalt, metal niobium and metal manganese; magnesium alloy can be selected from magnesium yttrium alloy, magnesium nickel alloy, magnesium aluminum alloy and magnesium cobalt alloy.

[0039] In the present invention, other raw materials except magnesium alloy are subjected to vacuum induction melting, and the other raw materials are preferably placed in different positions of the crucible of the vacuum induction furnace according to the characteristics of the raw materials. This is because the heating efficiency of the crucible in the vacuum induction melting furnace is different. For the same metal, the metal in the middle of the crucible will be heated to the melting point first. In order to improve the melting efficiency, shorten the melting time, save energy consumption, and reduce metal burning, it is necessary to place the raw materials according to a certain rule according to the characteristics of the metal raw materials and the different heating efficiencies of various parts of the vacuum induction melting furnace. This is a conventional technical means in the field, so the specific positions of each raw material will not be described in detail.

[0040] In the present invention, vacuum induction melting of the raw materials other than the magnesium alloy preferably includes: placing the raw materials other than the magnesium alloy in a vacuum induction furnace, evacuating the vacuum induction furnace, preheating and degassing, and then introducing inert gas to a vacuum degree of -0.06~-0.01MPa, and adjusting the power of the power supply to 10~20KW to melt all the materials.

[0041] In the present invention, the vacuum induction furnace is evacuated, and the vacuum degree is preferably 10-30Pa. In a specific embodiment, the vacuum degree can be 10Pa, 20Pa or 30Pa.

[0042] The present invention preferably uses a power supply to increase the temperature for the preheating degassing, and the power of the power supply is preferably 2-4 kW. In a specific embodiment, the power of the power supply can be 2 kW, 3 kW, or 4 kW; the working time of the power supply is preferably 5-10 min. In a specific embodiment, the working time of the power supply can be 5 min, 8 min, or 10 min. The present invention can better control the temperature by adjusting the heating rate through the heating power, and remove the gas and moisture adsorbed on the surface of the material.

[0043] After the preheating and degassing is completed, the present invention introduces an inert gas to a vacuum degree of preferably -0.06 to -0.01 MPa. In a specific embodiment, the inert gas introduced to a vacuum degree may be -0.06 MPa, -0.05 MPa, -0.04 MPa, -0.03 MPa, -0.02 MPa or -0.01 MPa. In the present invention, the inert gas is preferably argon.

[0044] After the inert gas is introduced until the vacuum reaches -0.06~-0.01MPa, the power of the power supply is adjusted to 10~20KW to melt all the materials. In a specific embodiment, the power of the adjusted power supply can be 10kW, 15kW or 20kW; after the power of the power supply reaches 10~20kW, the working time of the power supply is preferably 5~15min. In a specific embodiment, the working time of the power supply can be 5min, 10min or 15min. The power of the power supply is controlled to be 10~20kW and the working time is 5~15min, which can ensure that all the materials are melted (the temperature during melting is 1300~1400℃).

[0045] Specifically, in the embodiment, the raw materials are placed at different positions of the crucible of the vacuum induction furnace according to the material characteristics, the vacuum induction furnace is evacuated, the power is turned on for preheating and degassing, and after the degassing is completed, the vacuum pump is turned off, argon gas is introduced into the vacuum induction furnace, the power of the power supply is increased, and vacuum induction melting is performed to obtain a first melt.

[0046] After obtaining the first melt, the present invention introduces an inert gas to a pressure of 0.01-0.05 MPa, mixes the magnesium alloy and the first melt, and performs positive pressure induction melting to obtain a second melt.

[0047] In the present invention, the magnesium alloy is preferably placed in a secondary feeding device, and the secondary feeding device is used to feed the magnesium alloy.

[0048] In the present invention, before mixing the magnesium alloy and the first melt, it is preferred to reduce the power of the power supply to 3-5 kW, and continue to introduce inert gas to increase the pressure to the pressure of positive pressure induction melting (0.01-0.05 MPa), and then mix the magnesium alloy with the first melt after the first melt peels.

[0049] In the present invention, the power of the power supply is preferably reduced to 3-5 kW. In a specific embodiment, the power of the power supply can be reduced to 3 kW, 4 kW or 5 kW.

[0050] In the present invention, the magnesium alloy is preferably added into the first melt to achieve mixing of the magnesium alloy and the first melt.

[0051] In the present invention, the power of the power supply during the positive pressure induction melting is preferably 10~20kW. In a specific embodiment, the power of the power supply during the positive pressure induction melting can be 10kW, 15kW or 20kW. In the present invention, the working time of the power supply is preferably 4~6min. In a specific embodiment, the working time of the power supply can be 4min, 5min and 6min. In the present invention, the pressure during the positive pressure induction melting is preferably 0.01~0.05MPa. In a specific embodiment, the pressure can be 0.01MPa, 0.02MPa, 0.03MPa, 0.04MPa or 0.05MPa. In the present invention, by controlling the conditions of positive pressure induction melting, the temperature reached is 1300~1400℃.

[0052] Specifically, in an embodiment of the present invention, after obtaining the first melt, the power of the power supply is reduced, and argon gas is continued to be introduced into the vacuum induction furnace to the required pressure. After the surface of the first melt is peeled, the magnesium alloy in the secondary feeding device is added to the crucible, and the power of the power supply is increased to make the magnesium alloy melt quickly and mix evenly to obtain the second melt.

[0053] The present invention first melts the raw materials other than the magnesium alloy, and then melts the magnesium alloy, which can reduce the melting time of the magnesium alloy and further reduce the volatilization of magnesium. Positive pressure melting can increase the boiling point of the magnesium alloy, reduce the temperature difference, and further reduce the volatilization of magnesium, thereby ensuring the accuracy of the alloy formula. When performing positive pressure melting, after the surface of the first melt peels off, the power of the power supply is increased, so that the magnesium alloy is melted quickly, the melting time of the magnesium alloy is reduced, and further the volatilization of magnesium is reduced.

[0054] After obtaining the second melt, the present invention casts the second melt to obtain an ingot.

[0055] Before the casting, the present invention preferably reduces the power of the power supply to 3-5 kW; in a specific embodiment, the power of the power supply can be 3 kW, 4 kW and 5 kW.

[0056] The present invention has no special requirements on the casting method, and the commonly used technical means in the art can be used. Specifically, the present invention flows the second melt into a casting mold for casting, cooling, and obtaining an ingot.

[0057] After obtaining the ingot, the present invention performs rotary annealing on the ingot to obtain the magnesium- and yttrium-containing alloy.

[0058] In the present invention, the rotary annealing is preferably carried out in an inert gas, and the inert gas is preferably argon; the atmosphere pressure of the rotary annealing is preferably 0.01~0.05MPa. In a specific embodiment, the atmosphere pressure of the rotary annealing can be 0.01MPa, 0.02MPa, 0.03MPa, 0.04MPa or 0.05MPa.

[0059] In the present invention, the temperature of the rotary annealing is preferably 700-1200°C. In a specific embodiment, the temperature of the rotary annealing can be 700°C, 800°C, 900°C, 1000°C, 1100°C or 1200°C; the time of the rotary annealing is preferably 6-15h. In a specific embodiment, the time of the rotary annealing can be 6h, 8h, 10h, 12h and 15h.

[0060] The present invention utilizes rotary annealing to anneal the ingot, and the rotary annealing has a faster annealing efficiency, shortens the annealing time, and further reduces the volatilization of magnesium.

[0061] In the present invention, the power supply is preferably a medium frequency power supply.

[0062] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be clearly and completely described in conjunction with specific embodiments below. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Any modification, equivalent replacement, improvement, etc. made to the implementation methods of the present invention based on the technical essence and general principles of the present invention without creative work should be within the scope of protection of the present invention.

[0063] Example 1

[0064] According to the chemical formula La 0.55 Y 0.20 Mg 0.25 Ni 3.44 Al 0.08(Magnesium content 2.00%) Calculate the feed ratio of each raw material, weigh 3000g of metal lanthanum, metal nickel, metal aluminum, yttrium nickel alloy and magnesium yttrium alloy, pre-load the magnesium yttrium alloy into the secondary feeding device of the true induction furnace, and load the remaining materials into the crucible. After the feeding is completed, cover the furnace cover and turn on the vacuum system. When the vacuum degree in the furnace reaches 20Pa, turn on the medium frequency power supply to heat up and preheat and degas, and work at 3.0kW for 8min. After the material is preheated and degassed, introduce argon into the furnace to a vacuum degree of -0.04MPa. Increase the power of the medium frequency power supply to 15kW and work for 10min. After the material in the crucible is quickly and evenly melted, reduce the power of the medium frequency power supply to 4kW, and continue to introduce argon into the furnace until the pressure is 0.01MPa. After the melt is cooled to the point where the surface peels off, add the magnesium-yttrium alloy into the crucible, increase the medium-frequency power supply to 15kW again, work for 5 minutes, and quickly heat up and melt the magnesium-yttrium alloy until it is evenly mixed. Reduce the medium-frequency power supply to 4kW, and flow the melt to the casting mold for casting into an ingot. After the casting is completed, adjust the medium-frequency power supply to 0kW, cool for 60 minutes, and obtain a magnesium-yttrium alloy ingot. Place the alloy ingot in a rotary annealing furnace with an argon pressure of 0.01MPa and 800°C, anneal for 12 hours, and cool to obtain a magnesium-yttrium alloy.

[0065] The magnesium- and yttrium-containing alloy was crushed and fed into an impact mill for grinding, and then sieved through a 200-mesh screen to obtain 2786 g of metal powder.

[0066] The Mg content in the metal powder was measured using an inductively coupled plasma optical emission spectrometer (ICP-OES). The discharge capacity, hydrogen absorption, hydrogen absorption pressure, and hydrogen release pressure were tested according to the national standard GBT 31963-2015 "Rare earth magnesium superlattice hydrogen storage alloy powder for metal hydride-nickel battery negative electrode". The test showed that the Mg content was 1.98% and the maximum discharge capacity at 1C was 365mAh·g -1 , hydrogen absorption capacity 1.36wt%, hydrogen absorption pressure 0.098MPa, hydrogen release pressure 0.045MPa.

[0067] Example 2

[0068] According to the chemical formula La 0.55 Y 0.20 Mg 0.25 Ni 3.34 Co 0.1 Al 0.08(Magnesium content 2.00%) Calculate the feeding ratio of each raw material, weigh 3000g of metal lanthanum, metal nickel, metal cobalt, metal aluminum, yttrium nickel alloy and magnesium nickel alloy, pre-load the magnesium nickel alloy into the secondary feeding device of the true induction furnace, and load the remaining materials into the crucible. After the feeding is completed, cover the furnace cover and turn on the vacuum system. When the vacuum degree in the furnace reaches 20Pa, turn on the medium frequency power supply to heat up and preheat and degas, and work at 3.0kW for 8min. After the material is preheated and degassed, introduce argon into the furnace to a vacuum degree of -0.05MPa. Increase the power of the medium frequency power supply to 15kW and work for 10min. After the material in the crucible is quickly melted and evenly, reduce the power of the medium frequency power supply to 4kW, and continue to introduce argon into the furnace until the pressure is 0.02MPa. After the melt is cooled to the point where the surface peels off, add the magnesium-nickel alloy into the crucible, increase the medium-frequency power supply to 15kW again, work for 5 minutes, heat the magnesium-nickel alloy rapidly and melt it until it is evenly mixed, reduce the medium-frequency power supply to 4kW, and flow the melt to the casting mold for casting into an ingot. After the casting is completed, adjust the medium-frequency power supply to 0kW, cool for 60 minutes, and obtain a magnesium-containing yttrium-containing alloy ingot. Place the alloy ingot in a rotary annealing furnace at an argon pressure of 0.02MPa and 900℃, anneal for 12 hours, and cool to obtain a magnesium-containing yttrium-containing alloy.

[0069] The magnesium-containing and yttrium-containing alloy was crushed and fed into an impact mill for powdering, and then sieved through a 200-mesh screen to obtain 2812 g of metal powder. The test showed that the Mg content was 1.99% and the maximum discharge capacity at 1C was 369 mAh g -1 , hydrogen absorption capacity 1.30wt%, hydrogen absorption pressure 0.090MPa, hydrogen release pressure 0.048MPa.

[0070] Example 3

[0071] According to the chemical formula La 0.555 Y 0.20 Mg 0.245 Ni 3.39 Mn 0.05 Al 0.08(Magnesium content 1.95%) Calculate the feed ratio of each raw material, weigh 3000g of metal lanthanum, metal nickel, metal aluminum, metal manganese, yttrium nickel alloy and magnesium aluminum alloy, pre-load the magnesium aluminum alloy into the secondary feeding device of the true induction furnace, and load the remaining materials into the crucible. After the feeding is completed, cover the furnace cover and turn on the vacuum system. When the vacuum degree in the furnace reaches 20Pa, turn on the medium frequency power supply to heat up and preheat and degas, and work at 3.0kW for 8min. After the material is preheated and degassed, argon is introduced into the furnace to a vacuum degree of -0.03MPa. Increase the power of the medium frequency power supply to 15kW and work for 10min. After the material in the crucible is quickly melted and evenly, reduce the power of the medium frequency power supply to 4kW, and continue to introduce argon into the furnace until the pressure is 0.025MPa. After the melt is cooled to the point where the surface peels off, add the magnesium-aluminum alloy into the crucible, increase the medium-frequency power supply to 15kW again, work for 5 minutes, heat the magnesium-aluminum alloy rapidly and melt it until it is evenly mixed, reduce the medium-frequency power supply to 4KW, and flow the melt to the casting mold for casting into an ingot. After the casting is completed, adjust the medium-frequency power supply to 0kW, cool for 60 minutes, and obtain a magnesium-containing yttrium-containing alloy ingot. Place the alloy ingot in a rotary annealing furnace with an argon pressure of 0.025MPa and 1000℃, anneal for 8h, and cool to obtain a magnesium-containing yttrium-containing alloy.

[0072] The magnesium-containing yttrium alloy was crushed and fed into an impact mill for powdering, and then sieved through a 200-mesh screen to obtain 2808 g of metal powder. The test showed that the Mg content was 1.94% and the maximum discharge capacity at 1C was 359 mAh g -1 , hydrogen absorption capacity 1.31wt%, hydrogen absorption pressure 0.10MPa, hydrogen release pressure 0.055MPa.

[0073] Example 4

[0074] According to the chemical formula La 0.555 Y 0.20 Mg 0.245 Ni 3.34 Nd 0.05 Co 0.05 Al 0.08(Magnesium content 1.95%) Calculate the feed ratio of each raw material, weigh 3000g of metal lanthanum, metal nickel, metal niobium, metal aluminum, yttrium nickel alloy and magnesium cobalt alloy, pre-load the magnesium cobalt alloy into the secondary feeding device of the true induction furnace, and load the remaining materials into the crucible. After the feeding is completed, cover the furnace cover and turn on the vacuum system. When the vacuum degree in the furnace reaches 20Pa, turn on the medium frequency power supply to heat up and preheat and degas, and work at 3.0kW for 8min. After the material is preheated and degassed, introduce argon into the furnace to a vacuum degree of -0.02MPa. Increase the power of the medium frequency power supply to 15kW and work for 10min. After the material in the crucible is quickly melted and evenly, reduce the power of the medium frequency power supply to 4kW, and continue to introduce argon into the furnace until the pressure is 0.01MPa. After the melt is cooled to the point where the surface peels off, add the magnesium-cobalt alloy into the crucible, increase the medium-frequency power supply to 15kW again, work for 5 minutes, heat the magnesium-cobalt alloy rapidly and melt it until it is evenly mixed, reduce the medium-frequency power supply to 4kW, and flow the melt to the casting mold for casting into an ingot. After the casting is completed, adjust the medium-frequency power supply to 0kW, cool for 60 minutes, and obtain a magnesium-containing yttrium-containing alloy ingot. Place the alloy ingot in a rotary annealing furnace with an argon pressure of 0.01MPa and 1100℃, anneal for 8h, and cool to obtain a magnesium-containing yttrium-containing alloy.

[0075] The magnesium-containing and yttrium-containing alloy was crushed and fed into an impact mill for powdering, and then sieved through a 200-mesh screen to obtain 2801 g of metal powder. The test showed that the Mg content was 1.95% and the maximum discharge capacity at 1C was 371 mAh g -1 , hydrogen absorption capacity 1.38wt%, hydrogen absorption pressure 0.090MPa, hydrogen release pressure 0.046MPa.

[0076] Comparative Example 1

[0077] According to the chemical formula La 0.55 Y 0.20 Mg 0.25 Ni 3.44 Al 0.08 (Magnesium content 2.00%) Calculate the feed ratio of each raw material, weigh 3000g of metal lanthanum, metal nickel, metal aluminum, yttrium nickel alloy and magnesium yttrium alloy and put them into the crucible. After the addition is completed, cover the furnace cover and turn on the vacuum system. When the vacuum degree in the furnace reaches 20Pa, turn on the medium frequency power supply to heat up and preheat and degas, and work at 3.0kW for 8min. After the material is preheated and degassed, argon is introduced into the furnace to a vacuum degree of -0.04MPa. Increase the power of the medium frequency power supply to 15kW, work for 10min, and after the material in the crucible is quickly and evenly melted, reduce the power of the medium frequency power supply to 4kW, and flow the melt to the casting mold for casting into an ingot. After the casting is completed, adjust the power of the medium frequency power supply to 0kW, cool for 60min, and obtain a magnesium-containing yttrium-containing alloy ingot. The alloy ingot is placed in a rotary annealing furnace with an argon pressure of 0.01MPa and 800℃, annealed for 12h, and cooled to obtain a magnesium-containing yttrium-containing alloy.

[0078] The magnesium-containing and yttrium-containing alloy was crushed and fed into an impact mill for powdering, and then sieved through a 200-mesh screen to obtain 2762 g of metal powder. The test showed that the Mg content was 1.23% and the maximum discharge capacity at 1C was 352 mAh g -1 , hydrogen absorption capacity 1.28wt%, hydrogen absorption pressure 0.168MPa, hydrogen release pressure 0.094MPa.

[0079] Comparative Example 2

[0080] According to the chemical formula La 0.55 Y 0.20 Mg 0.25 Ni 3.44 Al 0.08 (Magnesium content 2.00%) Calculate the feed ratio of each raw material, weigh 3000g of metal lanthanum, metal magnesium, metal nickel, metal aluminum, and yttrium nickel alloy and put them into the crucible. After the addition is completed, cover the furnace cover and turn on the vacuum system. When the vacuum degree in the furnace reaches 20Pa, turn on the medium frequency power supply to heat up and preheat and degas, and work at 3.0kW for 8min. After the material is preheated and degassed, argon is introduced into the furnace to a vacuum degree of -0.04MPa. Increase the power of the medium frequency power supply to 15kW, work for 10min, and after the material in the crucible is quickly and evenly melted, reduce the power of the medium frequency power supply to 4kW, and flow the melt to the casting mold for casting into an ingot. After the casting is completed, adjust the power of the medium frequency power supply to 0kW, cool for 60min, and obtain a magnesium-containing yttrium-containing alloy ingot. The alloy ingot is placed in a rotary annealing furnace with an argon pressure of 0.01MPa and 800℃, annealed for 12h, and cooled to obtain a magnesium-containing yttrium-containing alloy.

[0081] The magnesium-containing and yttrium-containing alloy was crushed and fed into an impact mill for powdering, and then sieved through a 200-mesh screen to obtain 2762 g of metal powder. The test showed that the Mg content was 1.01% and the maximum discharge capacity at 1C was 341 mAh g -1 , hydrogen absorption capacity 1.23wt%, hydrogen absorption pressure 0.174MPa, hydrogen release pressure 0.091MPa.

[0082] The magnesium-containing and yttrium-containing alloy obtained in Example 1 was subjected to XRD test, and the results were as follows: Figure 1 .from Figure 1 As shown, the main phase of the magnesium- and yttrium-containing alloy prepared in the present invention is an A2B7 type phase.

[0083] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a magnesium-containing yttrium-containing alloy, characterized in that: The following steps are involved: Weigh raw materials according to the ratio of each metal element in the magnesium-containing and yttrium-containing alloy, wherein the raw material corresponding to the Mg element is a magnesium alloy; performing vacuum induction melting on raw materials other than the magnesium alloy to obtain a first melt; Introducing an inert gas to a pressure of 0.01-0.05 MPa, mixing the magnesium alloy and the first melt, and performing positive pressure induction melting to obtain a second melt; Casting the second melt to obtain an ingot; The ingot is subjected to rotary annealing to obtain the magnesium-containing and yttrium-containing alloy; Before mixing the magnesium alloy and the first melt, first reduce the power of the power supply to 3-5 kW, and continue to introduce inert gas to increase the pressure to the pressure of positive pressure induction melting, and after the surface of the first melt peels off, mix the magnesium alloy and the first melt; The power of the power supply during the positive pressure induction melting is 10-20kW; By controlling the pressure, time and power of positive pressure induction melting, the melting temperature can reach 1300~1400℃.

2. The preparation method according to claim 1, characterized in that: The temperature of the rotation annealing is 700-1200° C., and the time is 6-15 hours.

3. The preparation method according to claim 1 or 2, characterized in that: The atmosphere pressure of the rotary annealing is 0.01-0.05 MPa.

4. The preparation method according to claim 1 or 2, characterized in that: The spin annealing is performed in an inert gas.

5. The preparation method according to claim 1, characterized in that: The magnesium- and yttrium-containing alloy includes La.

6. The preparation method according to claim 1 or 5, characterized in that: The magnesium- and yttrium-containing alloy further includes at least two of Ni, Al, Co, Nb and Mn.

7. The preparation method according to claim 1, characterized in that: The vacuum induction melting of the raw materials other than the magnesium alloy comprises: The raw materials other than the magnesium alloy are placed in a vacuum induction furnace, the vacuum induction furnace is evacuated, preheated and degassed, and then inert gas is introduced until the vacuum degree is -0.06~-0.01MPa, and the power of the power supply is adjusted to 10~20kW to melt all the materials.

8. The preparation method according to claim 1 or 7, characterized in that: The power supply is a medium frequency power supply.

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