An easily activated Ti-Fe-Gd-Mn-Zr-Zn-V based hydrogen storage alloy and its preparation method

Abstract

This invention relates to an easily activated Ti-Fe-Gd-Mn-Zr-Zn-V based hydrogen storage alloy and its preparation method, belonging to the technical field of hydrogen storage alloy materials. It solves at least one of the problems in existing Ti-Fe based hydrogen storage alloys, such as high activation difficulty, long activation cycle, and poor hydrogen absorption / desorption kinetics. This invention provides a Ti-Fe-Gd-Mn-Zr-Zn-V based hydrogen storage alloy, wherein the chemical formula of the hydrogen storage alloy is Ti... 1.1 Fe 0.85 Gd 0.05 Mn 0.35‑x‑y‑z Zr x Zn y V z In the formula, x, y, and z are atomic ratios, where 0.05 ≤ x < 0.15, 0.02 ≤ y ≤ 0.08, and 0.05 ≤ z ≤ 0.1. The Ti-Fe-Gd-Mn-Zr-Zn-V based hydrogen storage alloy provided by this invention, through improved composition design and preparation process, achieves excellent activation and hydrogen absorption / desorption performance. It can be activated in one step at 30℃ and 3MPa, with a hydrogen absorption plateau pressure ≥ 0.39MPa and a hydrogen desorption plateau pressure ≥ 0.28MPa.

Description

Technical Field

[0001] This invention relates to the field of hydrogen storage alloy materials technology, and in particular to an easily activated Ti-Fe-Gd-Mn-Zr-Zn-V based hydrogen storage alloy and its preparation method. Background Technology

[0002] TiFe alloys possess advantages such as low cost, high capacity, low hydrogen absorption / desorption temperature, and good reversibility, making them a promising solid-state hydrogen storage material. However, the initial hydrogenation (activation) of TiFe alloys is typically difficult. Studies have confirmed that activation of TiFe alloys can only be achieved through exposure to high temperatures (673 K) and high pressures.

[0003] Over the past 30 years, numerous modifications have been made to TiFe alloys, including partial substitution of Fe or Ti with one or more elements through alloying, chemical surface modification, and mechanical alloying. Studies have shown that mechanically alloyed TiFe can be easily activated; however, the presence of an amorphous phase reduces its hydrogen storage capacity. Surface modification can promote hydrogenation by catalyzing the dissociation and chemical adsorption of hydrogen molecules with a transition metal or alloy deposited on the surface, or by eliminating a stable oxide layer with acids or bases. These methods also help improve the poisoning resistance of TiFe alloys. Among these methods, element substitution is considered the most feasible and has been extensively studied. When Fe is partially replaced by Ni, Co, Al, V, Pd, Mn, or Cr, the activation rate of the alloy is high. The addition of Mn has been found to be very effective in improving activation characteristics and increasing permeability to impurities. However, this substitution leads to a decrease in plateau pressure and a more sloping plateau region, which is detrimental to the development of hydrogen storage devices and proton exchange membrane fuel cells.

[0004] In addition to improving the formulation of hydrogen storage materials, people have also explored the processing methods of hydrogen storage alloys. TiFe alloys containing a small amount of Ni have good hydrogen absorption performance after ball milling for 20 to 30 hours under Ar gas protection. They are easy to activate or even do not require activation. However, the ball milling time is too long, which is not conducive to large-scale production.

[0005] Therefore, it is necessary to develop a novel Ti-Fe-based hydrogen storage material that is easy to activate, has excellent hydrogen absorption and desorption properties, and is simple to prepare and process. Summary of the Invention

[0006] Based on the above analysis, the present invention aims to provide an easily activated Ti-Fe-Gd-Mn-Zr-Zn-V based hydrogen storage alloy and its preparation method, in order to solve at least one of the problems in the prior art, such as high activation difficulty, long activation cycle, and poor hydrogen absorption and desorption kinetics performance of Ti-Fe based hydrogen storage alloys.

[0007] This invention provides a Ti-Fe-Gd-Mn-Zr-Zn-V based hydrogen storage alloy, wherein the chemical formula of the hydrogen storage alloy is Ti 1.1 Fe 0.85 Gd 0.05 Mn 0.35-x-y-z Zr x Zn y V z In the formula, x, y, z are atomic ratios, 0.05≤x<0.15, 0.02≤y≤0.08, 0.05≤z≤0.1.

[0008] Preferably, x:y:z = 0.1:0.04:0.08.

[0009] Furthermore, the hydrogen storage alloy comprises a multiphase structure containing a TiFe phase and an intermetallic compound ZrMn2 phase, with the ZrMn2 phase accounting for approximately 2% to 14% of the TiFe phase.

[0010] Furthermore, the hydrogen storage alloy has a nanocrystalline structure with an average grain size of 25–35 nm.

[0011] Furthermore, the hydrogen storage alloy can be activated in one operation at 30°C and 3 MPa hydrogen pressure, with a hydrogen absorption plateau pressure ≥0.39 MPa and a hydrogen release plateau pressure ≥0.28 MPa.

[0012] The present invention also provides a method for preparing the hydrogen storage alloy, comprising the following specific steps:

[0013] S1: Prepare the ingredients according to the preset chemical formula, with a certain proportion of burn-off loss added when weighing Mn, Zn and rare earth Gd;

[0014] S2: Place the prepared raw materials in the zirconium oxide crucible in sequence. Place the pure iron rod vertically along the crucible wall, place the blocky rare earth Gd at the bottom of the crucible, place the sponge Ti and Zr on top of the rare earth, place the electrolytic V and Mn on top of the sponge Ti and Zr, and finally add the metallic Zn.

[0015] S3: After the materials are placed in order, the furnace lid is closed, the furnace is evacuated and then filled with pure argon as a protective gas and heated to obtain a molten liquid master alloy. After holding the molten state for a period of time, the liquid alloy is poured into a copper casting mold to obtain a master alloy ingot.

[0016] S4: After mechanically crushing and sieving the master alloy ingot, the undersize alloy powder is obtained. It is then loaded into a stainless steel ball mill jar together with stainless steel grinding balls. After vacuuming, high-purity argon gas is introduced, and the mixture is ball-milled in an all-around planetary high-energy ball mill to obtain the ball-milled alloy powder, which is the hydrogen storage alloy.

[0017] Specifically, the burn-off amount of Mn, Zn and rare earth Gd in step S1 is 5% to 10%.

[0018] Specifically, the process and parameters for step S3 are as follows:

[0019] After closing the furnace lid, evacuate to a vacuum level of 1×10. -2 ~5×10 -5 Pa, filled with pure argon gas at a pressure of 0.01 to 0.1 MPa as a protective gas, melting temperature of 1550 to 1700℃, and melting holding time of 3 to 5 minutes.

[0020] Specifically, in step S4, a 200-mesh sieve is used for sieving, and the diameter of the alloy powder passing through the sieve is ≤75μm.

[0021] Specifically, the specific parameters for the ball milling operation in step S4 are: ball-to-material ratio 1:15-25, rotation speed 300-500 rpm, and ball milling time 0.5-2.0 hours.

[0022] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0023] 1. The Ti-Fe-Gd-Mn-Zr-Zn-V based hydrogen storage alloy provided by this invention is easy to activate, has high hydrogen storage capacity, and good hydrogen absorption and desorption performance. This invention combines chemical modification (formula optimization) and microstructure improvement (smelting + short-time ball milling). First, alloying with rare earth element Gd and transition metals Mn, Zr, Zn, and V reduces the activation conditions of the TiFe alloy and shortens the activation cycle. Then, short-time ball milling of the as-cast sample improves its microstructure, overcoming the drawbacks of Ti-Fe based hydrogen storage alloys while retaining their advantages. This significantly improves the overall performance of the novel hydrogen storage alloy, as will be explained below:

[0024] This invention adds Zr and Mn elements to the Ti-Fe alloy. Zr and Mn can form the ZrMn2 phase, an intermetallic compound that significantly improves activation ability and hydrogen storage capacity. The added rare earth element Gd preferentially absorbs hydrogen before TiFe, forming the hydride GdH. x Increasing cell volume and defect density improves the activation performance of the alloy. Furthermore, the addition of Zn significantly improves the corrosion resistance of the alloy and slightly enhances its activation performance. The addition of V significantly increases the cell volume of the TiFe alloy and refines the grains, thus significantly improving its activation performance. These elements improve the alloy's activation performance through different mechanisms and do not produce adverse effects; they work synergistically to maximize the activation performance. The addition of Zn not only improves the activation performance but also enhances the alloy's cycle stability.

[0025] Mechanical ball milling significantly reduces the grain size of the alloy and creates numerous crystal defects, increasing hydrogen nucleation sites and diffusion channels, further reducing the thermal stability of the hydride and improving the hydrogen absorption and desorption kinetics of the alloy.

[0026] The hydrogen storage alloy can be activated in one step at 30°C and 3 MPa hydrogen pressure, with a hydrogen absorption plateau pressure ≥0.39 MPa and a hydrogen release plateau pressure ≥0.28 MPa.

[0027] 2. The hydrogen storage alloy preparation method provided by this invention uses readily available raw materials, common equipment, relatively mild process conditions, is easy to operate, and has a short processing time, making it suitable for large-scale manufacturing and widespread application.

[0028] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0029] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0030] Figure 1 The XRD diffraction patterns of the as-cast alloys in Examples 1-6 are shown below.

[0031] Figure 2 The images show the SEM morphology of the ball-milled alloy powders in Examples 1-6.

[0032] Figure 3 The XRD patterns of the ball-milled alloy powders in Examples 1-6 are shown below.

[0033] Figure 4 The images show the HRTEM morphology of the ball-milled alloys in Examples 1-6 (red dashed lines indicate the locations of lattice defects). Detailed Implementation

[0034] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0035] This invention provides a Ti-Fe-Gd-Mn-Zr-Zn-V based hydrogen storage alloy, wherein the chemical formula of the hydrogen storage alloy is Ti 1.1 Fe 0.85 Gd 0.05 Mn0.35-x-y-z Zr x Zn y V z In the formula, x, y, z are atomic ratios, 0.05≤x<0.15, 0.02≤y≤0.08, 0.05≤z≤0.1.

[0036] The roles and contents of the above components are determined based on the following:

[0037] Ti and Fe: Ti and Fe are the main components in the alloy. The TiFe phase formed is the main phase for hydrogen absorption and desorption reactions. If the proportion is too low, the hydrogen storage capacity of the alloy will be reduced.

[0038] Gd: During the initial hydrogen absorption, it preferentially absorbs hydrogen over the TiFe phase, forming rare earth hydrides GdH. x This improves the activation performance of the alloy, but GdH x Since it does not participate in the hydrogen release reaction, the Gd content should not be too high, so as not to excessively reduce the hydrogen storage capacity of the alloy.

[0039] Zr, Mn: The generated ZrMn2 can participate in hydrogen absorption and desorption reactions, improve the activation performance of the alloy, and slightly increase the hydrogen storage capacity of the alloy. However, too much ZrMn2 phase will reduce the stability of the hydrogen absorption and desorption plateau pressure of the alloy, which is not conducive to the application of the alloy.

[0040] The addition of V can significantly increase the cell volume of TiFe alloy and refine the grains of the alloy, thereby improving the activation performance of the alloy. However, the addition of V will reduce the hydrogen storage capacity of the alloy.

[0041] Zn: Zn can improve the corrosion resistance of the alloy, thereby improving the cycle stability of the alloy. At the same time, the addition of Zn can also increase the defect density of the alloy, thereby slightly improving the activation performance of the alloy. However, too much Zn will reduce the hydrogen storage capacity of the alloy.

[0042] From the roles of these elements, it can be seen that TiFe is the main phase participating in the hydrogen absorption and desorption reactions of the alloy. The addition of other elements can improve the activation performance of the alloy, but they also have certain adverse effects. For example, Gd, V, and Zn will reduce the hydrogen storage capacity of the alloy, while Zr and Mn will reduce the stability of the hydrogen absorption and desorption plateau pressure. Therefore, to ensure the hydrogen storage capacity and plateau pressure stability of the alloy, the amount of each element added must be strictly controlled. Multiple experiments have shown that Ti... 1.1 Fe 0.85 Gd 0.05 Mn 0.35-x-y-z Zr x Zn y V z The optimal choice for x:y:z is 0.1:0.04:0.08.

[0043] Furthermore, the hydrogen storage alloy has a multiphase structure containing a TiFe phase and an intermetallic compound ZrMn2 phase, with the ZrMn2 phase accounting for approximately 2% to 14% of the TiFe phase. Excessive ZrMn2 phase will reduce the stability of the hydrogen absorption and desorption plateau pressure of the alloy, which is not conducive to the application of the alloy.

[0044] Furthermore, the hydrogen storage alloy has a nanocrystalline structure with an average grain size of 25–35 nm. The small grain size, combined with a large number of crystal defects (…), Figure 4 (The red dashed lines in the middle represent the locations of lattice defects), which helps to reduce the thermal stability of hydrides and improve the hydrogen absorption and desorption kinetics of the alloy.

[0045] Furthermore, the hydrogen storage alloy can be activated in one operation at 30°C and 3 MPa hydrogen pressure, with a hydrogen absorption plateau pressure ≥0.39 MPa and a hydrogen release plateau pressure ≥0.28 MPa.

[0046] The present invention also provides a method for preparing the hydrogen storage alloy, comprising the following specific steps:

[0047] S1: Prepare the ingredients according to the preset chemical formula, with a certain proportion of burn-off loss added when weighing Mn, Zn and rare earth Gd;

[0048] S2: Place the prepared raw materials in the zirconium oxide crucible in sequence. Place the pure iron rod vertically along the crucible wall, place the blocky rare earth Gd at the bottom of the crucible, place the sponge Ti and Zr on top of the rare earth, place the electrolytic V and Mn on top of the sponge Ti and Zr, and finally add the metallic Zn. This arrangement order is based on the morphology and melting point of each metal, which can ensure that all the metals can be melted, thereby forming an alloy with uniform element distribution.

[0049] S3: After the materials are placed in order, the furnace lid is closed, the furnace is evacuated and then filled with pure argon as a protective gas and heated to obtain a molten liquid master alloy. After holding the molten state for a period of time, the liquid alloy is poured into a copper casting mold to obtain a master alloy ingot.

[0050] S4: After mechanically crushing and sieving the master alloy ingot, the undersize alloy powder is obtained. It is then loaded into a stainless steel ball mill jar together with stainless steel grinding balls. After vacuuming, high-purity argon gas is introduced, and the mixture is ball-milled in an all-around planetary high-energy ball mill to obtain the ball-milled alloy powder, which is the hydrogen storage alloy.

[0051] In general, the core step of this preparation method lies in mechanical ball milling. Mechanical ball milling significantly reduces the grain size of the alloy while greatly increasing the density of grain boundaries and defects. This provides a channel for the rapid diffusion of hydrogen atoms within the alloy, thus significantly improving the hydrogen absorption / desorption kinetics while enhancing activation performance. Scientific composition design combined with appropriate ball milling processes can yield alloy powders with unique structures, thereby giving the alloy excellent activation performance. Process improvements and parameter optimizations in other supporting steps revolve around this key step, ultimately achieving better mechanical modification effects (microstructural modification, such as…). Figure 4 (As shown).

[0052] Specifically, the burn-off amount of Mn, Zn and rare earth Gd mentioned in step S1 is 5% to 10%. Mn, Zn and rare earth Gd are easy to volatilize and will be lost during the batching and heating melting process. Therefore, a certain amount of burn-off needs to be added, generally 5% to 8%, and no more than 10%.

[0053] Specifically, the process and parameters for step S3 are as follows:

[0054] After closing the furnace lid, evacuate to a vacuum level of 1×10. -2 ~5×10 -5 Pa, filled with pure argon gas at a pressure of 0.01 to 0.1 MPa as a protective gas, melting temperature of 1550 to 1700℃, and melting holding time of 3 to 5 minutes.

[0055] Specifically, in step S4, a 200-mesh sieve is used for sieving, and the diameter of the alloy powder passing through the sieve is ≤75μm. Preparing alloy particles of this size will not significantly increase costs and will also prepare the material for subsequent ball milling.

[0056] Specifically, the ball milling parameters in step S4 are: ball-to-material ratio of 1:15–25, rotation speed of 300–500 rpm, and milling time of 0.5–2.0 hours, preferably 1 hour. These milling parameters prevent the formation of excessive amorphous phases during milling, which could impair the alloy's hydrogen storage performance. Simultaneously, they significantly reduce the size of alloy particles and grains, maintaining an average grain size of 25–35 nm, thereby improving the alloy's activation performance and hydrogen absorption / desorption rates.

[0057] The chemical composition and proportions of specific embodiments of the present invention are selected as follows:

[0058] Example 1: Ti 1.1 Fe 0.85 Gd 0.05 Mn 0.13 Zr 0.1 Zn 0.04 V 0.08

[0059] Example 2: Ti 1.1 Fe 0.85 Gd 0.05 Mn 0.18 Zr 0.05 Zn 0.04 V 0.08

[0060] Example 3: Ti 1.1 Fe 0.85 Gd 0.05 Mn 0.08 Zr 0.15 Zn 0.04 V 0.08

[0061] Example 4: Ti 1.1 Fe 0.85 Gd 0.05 Mn 0.15 Zr 0.1 Zn 0.02 V 0.08

[0062] Example 5: Ti 1.1 Fe 0.85 Gd 0.05 Mn 0.16 Zr 0.1 Zn 0.04 V 0.05

[0063] Example 6: Ti 1.1 Fe 0.85 Gd 0.05 Mn 0.11 Zr 0.1 Zn 0.04 V 0.1

[0064] Comparative Example 1: Ti 1.1 Fe 0.8 Mn 0.2 (As-cast state)

[0065] According to the chemical composition of each embodiment, rare earth metal Gd, sponge Ti and Zr, high-purity Fe, electrolytic V and Mn, and metallic Zn are selected. The high-purity iron rod is polished with sandpaper to remove the surface oxide layer. The rare earth metal Gd and electrolytic Mn and Zn have a 5-8 wt.% loss on burn during the batching process. The technical parameters for each stage are as follows: the vacuum induction melting furnace is evacuated to 1×10⁻⁶ before heating. -2 ~5×10 -5Pa; then, 0.01-0.1 MPa of inert argon gas is introduced into the furnace as a protective gas; the temperature during induction heating is 1550-1700℃; the liquid alloy is held at the molten state for 3-5 minutes; the cast alloy is mechanically crushed and passed through a 200-mesh sieve, with a particle size of approximately 75 μm. The alloy powder is then loaded into a stainless steel ball mill jar along with stainless steel grinding balls and ball-milled using an omnidirectional planetary ball mill for 0.5-2 hours.

[0066] It is worth emphasizing that all process parameters can be appropriately selected within the above range to prepare the hydrogen storage alloy powder described in the patent. Therefore, although only one typical embodiment has been given in this invention, this embodiment is applicable to preparation methods with different parameters.

[0067] Process parameters for Example 1:

[0068] According to the chemical formula Ti 1.1 Fe 0.85 Gd 0.05 Mn 0.13 Zr 0.1 Zn 0.04 V 0.08 Bulk rare earth metal Gd, sponge Ti and Zr, pure Fe, electrolytic V and Mn, and metallic Zn were selected. These metals had a purity of 99.5% and were weighed according to stoichiometric ratios: sponge Ti 402.1 g, sponge Zr 69.7 g, pure iron 362.5 g, rare earth Gd 63.1 g, electrolytic Mn 57.3 g, electrolytic V 31.1 g, and metallic Zn 21.0 g. The weighed bulk metals were placed in a zirconia crucible of a medium-frequency induction furnace according to the designed process. A pure iron rod was placed vertically along the crucible wall, the bulk rare earth Gd was placed at the bottom of the crucible, the sponge Ti and Zr were placed above the rare earth Gd, and the electrolytic Mn and V were placed on top of the sponge Ti and Zr. Finally, Zn was added. The furnace lid was then closed, and a vacuum was evacuated for approximately 30 minutes to a vacuum degree of 5 × 10⁻⁶. -2 Above Pa, high-purity argon protective gas is then introduced until the pressure reaches -0.04 MPa. The heating temperature is adjusted to about 1700℃ to melt all the raw material metals. The molten liquid metal is kept at a constant temperature for 5 minutes to make it uniform. Then, the uniformly mixed liquid metal is poured into a cylindrical copper mold with a diameter of 30 mm and a depth of 80 mm. After cooling to room temperature in the furnace, it is removed to obtain the master alloy ingot.

[0069] Ti alloy 1.1 Fe 0.85 Gd 0.05 Mn 0.13 Zr 0.1 Zn 0.04 V 0.08After the ingot is mechanically crushed and passed through a 200-mesh sieve, 20 grams of the sieved alloy powder and 400 grams of stainless steel grinding balls are weighed and placed together in a 250 ml stainless steel ball mill jar. The jar is then evacuated, filled with high-purity argon gas, and sealed. The jar is then ball-milled for 1 hour in an all-around planetary high-energy ball mill.

[0070] The raw materials for Examples 2-6 and the comparative examples were weighed according to their chemical formulas, and other preparation process parameters were the same as those for Example 1.

[0071] The phase structure of the as-cast and ball-milled powders was determined by XRD. The morphology and microstructure of the ball-milled alloy particles were observed by high-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM), and the crystal state of the alloy was determined by selected area electron diffraction (SAED). The hydrogen absorption activation performance, hydrogen storage capacity, and hydrogen absorption and desorption kinetics of the alloy powder were tested using a semi-automatic Sieverts system. The hydrogen absorption temperature was 30℃, and the initial hydrogen pressure was 3 MPa; the hydrogen desorption temperature was 30℃, and the hydrogen desorption rate was 1 × 10⁻⁶ MPa. -4 The test was conducted at a pressure of MPa.

[0072] Table 1 Solid-state hydrogen storage performance of alloys from different embodiments (comparative examples)

[0073]

[0074] The above results demonstrate that the ball-milled alloy powder possesses excellent activation properties and high hydrogen absorption capacity. Clearly, the alloy preparation process of this invention is simple and easy to operate, fully suitable for large-scale production, and its performance meets the requirements of various applications for hydrogen storage materials. Compared with similar alloys at home and abroad, the hydrogen storage performance of the alloy of this invention is significantly improved, exhibiting obvious advantages.

[0075] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A Ti-Fe-Gd-Mn-Zr-Zn-V based hydrogen storage alloy, characterized in that, The hydrogen storage alloy has the chemical formula Ti. 1.1 Fe 0.85 Gd 0.05 Mn 0.35-x-y-z Zr x Zn y V z In the formula, x, y, z are atomic ratios, 0.05≤x<0.15, 0.02≤y≤0.08, 0.05≤z≤0.

1.

2. The hydrogen storage alloy according to claim 1, characterized in that, x:y:z = 0.1:0.04:0.

08.

3. The hydrogen storage alloy according to claim 1, characterized in that, The hydrogen storage alloy has a multiphase structure containing a TiFe phase and an intermetallic compound ZrMn2 phase, with the ZrMn2 phase accounting for 2% to 14% of the TiFe phase.

4. The hydrogen storage alloy according to claim 1, characterized in that, The hydrogen storage alloy has a nanocrystalline structure with an average grain size of 25–35 nm.

5. The hydrogen storage alloy according to claim 1, characterized in that, The hydrogen storage alloy can be activated in one operation at 30°C and 3 MPa hydrogen pressure, with a hydrogen absorption plateau pressure ≥0.39 MPa and a hydrogen release plateau pressure ≥0.28 MPa.

6. A method for preparing the hydrogen storage alloy according to any one of claims 1 to 5, characterized in that, The specific steps include the following: S1: Prepare the ingredients according to the preset chemical formula, with a certain proportion of burn-off loss added when weighing Mn, Zn and rare earth Gd; S2: Place the prepared raw materials in the zirconium oxide crucible in sequence. Place the pure iron rod vertically along the crucible wall, place the blocky rare earth Gd at the bottom of the crucible, place the sponge Ti and Zr on top of the rare earth, place the electrolytic V and Mn on top of the sponge Ti and Zr, and finally add the metallic Zn. S3: After the materials are placed in order, the furnace lid is closed, the furnace is evacuated and then filled with pure argon as a protective gas and heated to obtain a molten liquid master alloy. After holding the molten state for a period of time, the liquid alloy is poured into a copper casting mold to obtain a master alloy ingot. S4: After mechanically crushing and sieving the master alloy ingot, the undersize alloy powder is obtained. It is then loaded into a stainless steel ball mill jar together with stainless steel grinding balls. After vacuuming, high-purity argon gas is introduced, and the mixture is ball-milled in an all-around planetary high-energy ball mill to obtain the ball-milled alloy powder, which is the hydrogen storage alloy.

7. The preparation method according to claim 6, characterized in that, The loss of Mn, Zn and rare earth Gd in step S1 is 5% to 10%.

8. The preparation method according to claim 6, characterized in that, The specific process and parameters of step S3 are as follows: After closing the furnace lid, evacuate to a vacuum level of 1×10. -2 ~5×10 -5 Pa, filled with pure argon gas at a pressure of 0.01 to 0.1 MPa as a protective gas, melting temperature of 1550 to 1700℃, and melting holding time of 3 to 5 minutes.

9. The preparation method according to claim 6, characterized in that, In step S4, a 200-mesh sieve is used for sieving, and the diameter of the alloy powder passing through the sieve is ≤75μm.

10. The preparation method according to claim 6, characterized in that, The specific parameters for the ball milling operation in step S4 are: ball-to-material ratio 1:15-25, rotation speed 300-500 rpm, and ball milling time 0.5-2.0 hours.

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