Single-phase high-entropy hydrogen storage alloy and preparation method thereof

Abstract

This invention discloses a single-phase high-entropy hydrogen storage alloy and its preparation method, the chemical composition of which is Ti. x Cr y Mo z M r In the formula, x, y, z, r are atomic ratios, and 0.35≤x≤0.55, 0.35≤y≤0.55, 0.02≤z≤0.15, 0.02≤r≤0.15, and M is Mn or Fe. The preparation method of the above-mentioned high-entropy alloy hydrogen storage material is mainly to prepare it by batching, smelting, heat treatment and water quenching in sequence. The preparation method of the present invention is simple and easy to control. The prepared alloy has a stable structure, uniform alloy composition and grain size, and has excellent hydrogen absorption / desorption capacity and hydrogen desorption platform suitable for practical application. The maximum hydrogen absorption capacity is as high as 3.44 wt.%, the maximum hydrogen desorption capacity is as high as 2.37 wt.%, and the hydrogen desorption platform is higher than 0.2 MPa.

Description

Technical Field

[0001] This invention belongs to the technical field of solid-state hydrogen storage alloy materials, and relates to a single-phase high-entropy hydrogen storage alloy and its preparation method. Background Technology

[0002] Hydrogen energy is a crucial component in building a clean, low-carbon, safe, and efficient energy system. The hydrogen energy industry mainly comprises three key segments: hydrogen production, storage and transportation, and application. Commonly used hydrogen storage and transportation technologies include high-pressure gaseous hydrogen storage and cryogenic liquid hydrogen storage. High-pressure gaseous hydrogen storage is inexpensive, technologically mature, and has comprehensive supporting facilities, but it suffers from inherent drawbacks such as significant safety risks (storage pressure ~70 MPa) and low volumetric hydrogen density. Cryogenic liquid hydrogen storage offers high volumetric hydrogen density, but faces challenges such as easy leakage, high energy consumption, and high cost. Solid-state hydrogen storage technology, developed in recent years, offers high volumetric hydrogen density, low storage pressure, and high safety, making it highly promising for large-scale industrial application.

[0003] The core material for solid-state hydrogen storage technology is hydrogen storage alloy. Traditional alloy systems use a single element as the main component with trace amounts of other elements as dopants. This limits the controllability of the hydrogen absorption / desorption composition, making it difficult to balance hydrogen absorption and desorption performance. Chemical composition control is the most effective and direct means of regulating hydrogen storage performance. Therefore, based on traditional hydrogen storage alloy systems, it is difficult to obtain materials with balanced hydrogen absorption / desorption performance, making the development of novel hydrogen storage alloy materials imperative.

[0004] In recent years, the hydrogen storage properties of high-entropy alloys have been gradually explored. The multi-principal element design concept of high-entropy alloys, with multiple elements simultaneously as principal components, allows for a large controllable space for hydrogen absorption / desorption, enabling a better balance between the two. Simultaneously, the severe lattice distortion effect of high-entropy alloys allows them to break through the hydrogen storage limits of traditional alloys, providing significant potential for optimizing hydrogen storage performance. Although containing multiple principal elements, high-entropy alloys typically have a simple solid solution phase structure, such as BCC, FCC, or HCP structures. In the BCC structure, the number of interstitial sites occupied by hydrogen per unit metal atom is far greater than in other structures; all three octahedral and six tetrahedral sites can be occupied by hydrogen. Therefore, high-entropy alloys with BCC structures possess a broad compositional controllability space and a higher theoretical hydrogen storage capacity, making them a promising new hydrogen storage material. Classical BCC phase high-entropy hydrogen storage alloy systems generally contain three principal elements: Ti, V, and Cr, with other elements selectively added to the system. However, the high cost of V makes the alloy raw material too expensive, hindering large-scale application. However, when the V content in the Ti-V-Cr alloy is low (<10 at%), the phase structure of the alloy changes from a single-phase BCC structure to a multiphase structure, containing at least two or more phases (BC structure, C14-type Laves phase structure, and some metallic segregated phases), or even transforming into an alloy structure dominated by the C14-type Laves phase. At this point, the hydrogen storage capacity of the alloy decreases sharply. Studies have shown that when the alloy phase structure changes from a single-phase BCC to a multiphase structure, the hydrogen storage performance of the alloy deteriorates significantly. How to reduce the use of expensive elements such as V in the alloy system while maintaining a single BCC structure is fundamental to developing low-cost, high-performance BCC structure high-entropy hydrogen storage alloys.

[0005] To date, only a few studies have focused on preparing low-cost vanadium-free BCC-type high-entropy hydrogen storage alloys through element substitution. The paper "Understanding crystal structure roles towards developing high-performance V-free BCC hydrogen storage alloys" by HZHu, CMMa, L. Zhou, HQXiao, QJChen, 2022, 47:25335-25346 describes the preparation of a BCC-type Ti-Cr-Mo based alloy using arc melting. This alloy exhibits high hydrogen storage capacity and fast hydrogen absorption / desorption kinetics, but its reversible hydrogen release capacity and hydrogen release plateau pressure are insufficient for practical applications and require further improvement. Element doping is the simplest and most efficient method for modifying hydrogen storage alloys. Therefore, to significantly improve the reversible hydrogen release capacity of Ti-Cr-Mo based alloys, it is urgent to prepare multi-principal-element single-phase BCC-type high-entropy alloys doped with various elements. However, the formation conditions for BCC-structured alloys are quite demanding, and the formation of the BCC phase structure becomes even more difficult after multi-element doping. Currently, there are no reports on the preparation and hydrogen storage performance of single-phase BCC type Ti-Cr-Mo-M (M = Mn or Fe) based multi-principal element hydrogen storage alloys. Summary of the Invention

[0006] The purpose of this invention is to provide a single-phase high-entropy hydrogen storage alloy and its preparation method, wherein the general chemical formula of the alloy is Ti. x Cr y Mo z M r In the formula, x, y, z, and r are atomic ratios, where 0.35 ≤ x ≤ 0.55, 0.35 ≤ y ≤ 0.55, 0.02 ≤ z ≤ 0.15, and 0.02 ≤ r ≤ 0.15. This hydrogen storage alloy has a BCC-type body-centered cubic single-phase structure with a phase abundance of 100%. This invention uses an electric arc melting method, followed by a segmented heating and holding process heat treatment and water quenching, to prepare a single-phase BCC-type Ti-Cr-Mo-M (M = Mn or Fe)-based high-entropy hydrogen storage alloy. This alloy has high hydrogen storage capacity and reversible hydrogen release capacity, meeting the hydrogen release platform pressure requirements for practical applications, and has good potential for widespread application.

[0007] The technical solution of the present invention is as follows:

[0008] A single-phase high-entropy hydrogen storage alloy with the general chemical formula Ti x Cr y Mo z M rIn the formula: x, y, z, r are atomic ratios, 0.35≤x≤0.55, 0.35≤y≤0.55, 0.02≤z≤0.15, 0.02≤r≤0.15, and M is Mn or Fe.

[0009] As a limitation of the single-phase high-entropy hydrogen storage alloy of the present invention, the hydrogen storage alloy is a BCC-type body-centered cubic single-phase structure with a phase abundance of 100%.

[0010] The high-entropy hydrogen storage alloy of this invention has a reasonable chemical element and ratio composition. In this composition, Ti is a hydrogen-absorbing element, and Ti-based alloys can reversibly absorb and desorb large amounts of hydrogen at room temperature. Moreover, Ti is inexpensive and abundant. Cr, Mo, Mn, and Fe are hydrogen-desorbing elements, all of which are non-precious metal elements with low raw material costs. Cr and Mo have the strongest tendency to form a BCC crystal structure with Ti through solid solution, and the BCC structure is the crystal structure with the highest theoretical hydrogen storage capacity. Both the tetrahedral and octahedral interstices can store hydrogen. The doping of Mn and Fe further enhances the hydrogen absorption and desorption kinetics of the Ti-Cr-Mo ternary alloy and allows for precise and wide-range control of the hydrogen desorption plateau of the alloy according to specific application requirements. This further ensures that the hydrogen storage alloy has good comprehensive performance in terms of reversible hydrogen absorption and desorption capacity, hydrogen absorption and desorption kinetics, and hydrogen absorption and desorption plateau pressure.

[0011] This invention also provides a method for preparing a single-phase high-entropy hydrogen storage alloy, which is carried out in the following order:

[0012] (1) The ingredients are prepared according to the general formula of the chemical composition of high-entropy hydrogen storage alloy, and then the alloy is melted by electric arc. In the melting process, Cr and Mo metal elements are first melted into intermetallic compounds, and then the alloy is obtained by co-melting with other metal elements.

[0013] (2) Place the cast alloy inside a quartz tube, then evacuate the quartz tube and introduce an inert gas, then seal the quartz tube and perform heat treatment under a 0.04MPa argon atmosphere.

[0014] (3) Take out the quartz tube containing the heat-treated alloy after the above heat treatment, and put it into water at 25°C for water quenching to obtain the single-phase high-entropy hydrogen storage alloy.

[0015] As a limitation of the preparation method of the present invention, in step (1), the melting current is 100-300A, the melting time is 300s / time, and the number of melting times is 4-6 times.

[0016] As a second limitation of the preparation method of the present invention, in step (2), the heat treatment is carried out in the following order:

[0017] The heat treatment adopts a segmented heating process. When the temperature is below 1000℃, the heating rate is 5 to 15℃ / min. When the temperature reaches 1000℃, the temperature continues to rise to 1250 to 1400℃ at a heating rate of 1 to 2℃ / min, and is held for 2 to 6 hours.

[0018] In the segmented heat treatment process of this invention, when the temperature is below 1000℃, a relatively fast heating rate is controlled. During this process, a slow heating rate can easily cause the precipitation of some low-temperature phases. Rapid heating ensures the stability of the phase structure. When the temperature reaches 1000℃, the temperature is slowly increased to the target temperature. During this process, impurity phases other than the BCC phase have sufficient time to complete the transformation into the BCC structure. The final holding temperature is selected within the temperature range where the BCC phase is stable, and the optimal temperature value is chosen for holding. This further ensures the formation of the BCC single-phase structure.

[0019] As is well known, the formation of the BCC phase structure in Ti-Cr-Mo multi-element high-entropy alloys becomes more difficult after multi-element doping. This is mainly due to the large differences in melting points among the elements. Even when smelted into intermetallic compounds, their melting points still differ significantly. As the temperature decreases, the liquid phase easily segregates, resulting in a very small composition and temperature range for the stable existence of the BCC single-phase structure. This makes it more difficult to form a pure BCC phase structure, and whether or not it is a pure BCC phase structure further affects and restricts the alloy's hydrogen storage performance. The unique alloy chemical ratio and processing technology of this invention ensure that the alloy prepared by this invention has a pure BCC type body-centered cubic single-phase structure, thereby further guaranteeing its excellent hydrogen storage characteristics.

[0020] As a third limitation of the preparation method of the present invention, in step (3), the water quenching time is 1 min. Compared with traditional natural cooling, the water quenching treatment in the present invention can maintain the high-temperature stable BCC phase structure of the prepared alloy and avoid the precipitation of impurity phases during slow cooling.

[0021] The preparation method of the present invention also has a limitation: the hydrogen absorption capacity of the high-entropy hydrogen storage alloy is ≥3.24wt.%, the hydrogen release capacity is ≥2.07wt.%, and the hydrogen release platform pressure value is ≥0.25MPa.

[0022] The above preparation method, as a whole, has interconnected steps that jointly affect the structural characteristics and hydrogen storage performance of the final high-entropy alloy.

[0023] By adopting the above technical solution, the present invention has the following advantages compared with the prior art:

[0024] 1. The high-entropy alloy preparation of this invention adopts a step-by-step heat treatment method, which is beneficial to the elimination of impurity phases and the reduction of stress, resulting in a uniform alloy composition.

[0025] 2. The single-phase BCC type Ti-Cr-Mo-M (M = Mn or Fe) based high-entropy hydrogen storage alloy prepared by this invention has a high hydrogen storage capacity, as well as a high reversible hydrogen release capacity and a hydrogen release plateau pressure that meets the requirements of practical applications (hydrogen release plateau pressure ≥ 0.25 MPa).

[0026] 3. The single-phase BCC type high-entropy alloy prepared by this invention has stable performance, broad application prospects, and certain promotion and application value.

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0028] Figure 1 X-ray diffraction patterns of single-phase BCC type Ti-Cr-Mo-Mn and Ti-Cr-Mo-Fe based high-entropy hydrogen storage alloys prepared in Examples 1 and 2 of this invention;

[0029] Figure 2 The hydrogen absorption / desorption kinetics curves of the single-phase BCC type Ti-Cr-Mo-Mn and Ti-Cr-Mo-Fe based high-entropy hydrogen storage alloys prepared in Examples 1 and 2 of this invention are shown.

[0030] Figure 3 PCT curves of single-phase BCC type Ti-Cr-Mo-Mn and Ti-Cr-Mo-Fe based high-entropy hydrogen storage alloys prepared in Examples 1 and 2 of this invention. Detailed Implementation

[0031] Example 1 Ti 0.4 Cr 0.45 Mo 0.10 Mn 0.05 Preparation method of high entropy alloy

[0032] (1) According to the chemical composition Ti 0.4 Cr 0.45 Mo 0.10 Mn 0.05 The ingredients are prepared. During the smelting process, the elemental Cr and Mo metals are first smelted into intermetallic compounds, and then co-melted with Ti and Mn. The smelting current is 100-200A, the smelting time is 300s / cycle, and the smelting is repeated 4 times to obtain an alloy ingot.

[0033] (2) A 20g alloy ingot was wire-cut and placed inside a quartz tube. The quartz tube was then evacuated and inert gas was introduced. After sealing the quartz tube, it was placed in an open-type vacuum / atmosphere tube furnace. After repeated evacuation three times, argon gas at 0.04MPa was introduced and heat-treated. The heating program was started, and the alloy sample was heated from room temperature to 1000℃ at a rate of 5℃ / min, and then heated to 1400℃ at a rate of 1℃ / min, and held for 2 hours.

[0034] (3) After the heat preservation is completed, the quartz tube containing the sample is taken out at 1400℃ and placed in water at 25℃ for 1 min to obtain a high entropy alloy.

[0035] The sample obtained above was cut into 5 mm cubes, and the hydrogen storage performance of the alloy was determined by Sievert's method.

[0036] like Figure 1 As shown, the alloy prepared in Example 1 was subjected to XRD analysis, and the results proved that the alloy is a BCC type single-phase structure with a phase abundance of 100%.

[0037] like Figure 2 As shown, the alloy prepared in Example 1 has a hydrogen storage capacity of 3.27 wt.% and a hydrogen release capacity of 2.14 wt.%.

[0038] like Figure 3 As shown, the hydrogen absorption plateau of the alloy prepared in Example 1 is 1.75 MPa, and the hydrogen release plateau is 0.3 MPa.

[0039] Example 2Ti 0.4 Cr 0.45 Mo 0.10 Fe 0.05 Preparation method of high entropy alloy

[0040] (1) According to the chemical composition Ti 0.4 Cr 0.45 Mo 0.10 Fe 0.05 The ingredients are prepared. During the smelting process, the elemental Cr and Mo metals are first smelted into intermetallic compounds, and then co-melted with Ti and Fe. The smelting current is 150-300A, the smelting time is 300s / cycle, and the smelting is repeated 6 times to obtain an alloy ingot.

[0041] (2) A 20g alloy ingot was wire-cut and placed inside a quartz tube. The quartz tube was then evacuated and inert gas was introduced. After sealing the quartz tube, it was placed in an open-type vacuum / atmosphere tube furnace. After repeated evacuation three times, argon gas at 0.04MPa was introduced and heat-treated. The heating program was started, and the alloy sample was heated from room temperature to 1000℃ at a rate of 5℃ / min, and then heated to 1300℃ at a rate of 1℃ / min, and held for 6 hours.

[0042] (3) After the heat preservation is completed, the quartz tube containing the sample is taken out and quenched in water at 25°C for 1 minute to obtain the final high-entropy alloy.

[0043] The sample obtained above was cut into 5 mm cubes, and the hydrogen storage performance of the alloy was determined by Sievert's method.

[0044] like Figure 1 As shown, the alloy prepared in Example 2 was subjected to XRD analysis, and the results proved that the alloy has a BCC type single-phase structure.

[0045] like Figure 2 As shown, the alloy prepared in Example 2 has a hydrogen storage capacity of 3.34 wt.% and a hydrogen release capacity of 2.29 wt.%.

[0046] like Figure 3 As shown, the hydrogen absorption plateau of the alloy prepared in Example 2 is 2.23 MPa, and the hydrogen release plateau is 0.58 MPa.

[0047] Example 3Ti 0.50 Cr 0.40 Mo 0.05 Fe 0.05 Preparation method of high entropy alloy

[0048] (1) According to the chemical composition Ti 0.50 Cr 0.40 Mo 0.05 Fe 0.05 The ingredients are prepared. During the smelting process, the elemental Cr and Mo metals are first smelted into intermetallic compounds, and then co-melted with Ti and Fe. The smelting current is 150-300A, the smelting time is 300s / cycle, and the smelting is repeated 5 times to obtain an alloy ingot.

[0049] (2) A 20g alloy ingot was wire-cut and placed inside a quartz tube. The quartz tube was then evacuated and inert gas was introduced. After sealing the quartz tube, it was placed in an open-type vacuum / atmosphere tube furnace. After repeated evacuation three times, argon gas at 0.04MPa was introduced and heat-treated. The heating program was started, and the alloy sample was heated from room temperature to 1000℃ at a rate of 10℃ / min, and then heated to 1250℃ at a rate of 2℃ / min, and held for 4 hours.

[0050] (3) After the heat preservation is completed, the quartz tube containing the sample is taken out and quenched in water at 25°C for 1 minute to obtain a high-entropy alloy.

[0051] The sample obtained above was wire-cut into 5 mm cubes, and the hydrogen storage performance of the alloy was determined by Sievert's method.

[0052] Test results show that the alloy prepared in Example 3 has a BCC type single-phase structure, with a hydrogen storage capacity of 3.31 wt.%, a hydrogen release capacity of 2.07 wt.%, a hydrogen absorption plateau of 3.26 MPa, and a hydrogen release plateau of 0.84 MPa.

[0053] Example 4Ti 0.40 Cr 0.55 Mo 0.02 Mn 0.03 Preparation method of high entropy alloy

[0054] (1) According to the chemical composition Ti 0.40 Cr 0.55 Mo 0.02 Mn 0.03 The ingredients are prepared. During the smelting process, the elemental Cr and Mo metals are first smelted into intermetallic compounds, and then co-melted with Ti and Mn. The smelting current is 100-200A, the smelting time is 300s / cycle, and the smelting is repeated 4 times to obtain an alloy ingot.

[0055] (2) A 20g alloy ingot was wire-cut and placed inside a quartz tube. The quartz tube was then evacuated and inert gas was introduced. After sealing the quartz tube, it was placed in an open-type vacuum / atmosphere tube furnace. After repeated evacuation three times, argon gas at 0.04MPa was introduced and heat-treated. The heating program was started, and the alloy sample was heated from room temperature to 1000℃ at a rate of 15℃ / min, and then heated to 1300℃ at a rate of 1℃ / min, and held for 2 hours.

[0056] (3) After the heat preservation is completed, the quartz tube containing the sample is taken out and quenched in water at 25°C for 1 minute to obtain a high-entropy alloy.

[0057] The sample obtained above was cut into 5 mm cubes, and the hydrogen storage performance of the alloy was determined by Sievert's method.

[0058] Test results show that the alloy prepared in Example 4 has a BCC type single-phase structure, with a hydrogen storage capacity of 3.42 wt.%, a hydrogen release capacity of 2.37 wt.%, a hydrogen absorption plateau of 1.7 MPa, and a hydrogen release plateau of 0.34 MPa.

[0059] Example 5Ti 0.35 Cr0.35 Mo 0.15 Mn 0.02 Preparation method of high entropy alloy

[0060] (1) According to the chemical composition Ti 0.35 Cr 0.35 Mo 0.15 Mn 0.02 The ingredients are prepared. During the smelting process, the elemental Cr and Mo metals are first smelted into intermetallic compounds, and then co-melted with Ti and Mn. The smelting current is 100-200A, the smelting time is 300s / cycle, and the smelting is repeated 4 times to obtain an alloy ingot.

[0061] (2) A 20g alloy ingot was wire-cut and placed inside a quartz tube. The quartz tube was then evacuated and inert gas was introduced. After sealing the quartz tube, it was placed in an open-type vacuum / atmosphere tube furnace. After repeated evacuation three times, argon gas at 0.04MPa was introduced and heat-treated. The heating program was started, and the alloy sample was heated from room temperature to 1000℃ at a rate of 10℃ / min, and then heated to 1250℃ at a rate of 1℃ / min, and held for 2 hours.

[0062] (3) After the heat preservation is completed, the quartz tube containing the sample is taken out and quenched in water at 25°C for 1 minute to obtain a high-entropy alloy.

[0063] The sample obtained above was cut into 5 mm cubes, and the hydrogen storage performance of the alloy was determined by Sievert's method.

[0064] Test results show that the alloy prepared in Example 5 has a BCC type single-phase structure, with a hydrogen storage capacity of 3.24 wt.%, a hydrogen release capacity of 2.25 wt.%, a hydrogen absorption plateau of 1.1 MPa, and a hydrogen release plateau of 0.25 MPa.

[0065] Example 6Ti 0.55 Cr 0.5 Mo 0.1 Mn 0.15 Preparation method of high entropy alloy

[0066] (1) According to the chemical composition Ti 0.55 Cr 0.5 Mo 0.1 Mn 0.15 The ingredients are prepared. During the smelting process, the elemental Cr and Mo metals are first smelted into intermetallic compounds, and then co-melted with Ti and Mn. The smelting current is 100-200A, the smelting time is 300s / cycle, and the smelting is repeated 4 times to obtain an alloy ingot.

[0067] (2) A 20g alloy ingot was wire-cut and placed inside a quartz tube. The quartz tube was then evacuated and inert gas was introduced. After sealing the quartz tube, it was placed in an open-type vacuum / atmosphere tube furnace. After repeated evacuation three times, argon gas at 0.04MPa was introduced and heat-treated. The heating program was started, and the alloy sample was heated from room temperature to 1000℃ at a rate of 10℃ / min, and then heated to 1250℃ at a rate of 1℃ / min, and held for 2 hours.

[0068] (3) After the heat preservation is completed, the quartz tube containing the sample is taken out and quenched in water at 25°C for 1 minute to obtain a high-entropy alloy.

[0069] The sample obtained above was cut into 5 mm cubes, and the hydrogen storage performance of the alloy was determined by Sievert's method.

[0070] Test results show that the alloy prepared in Example 5 has a BCC type single-phase structure, with a hydrogen storage capacity of 3.44 wt.%, a hydrogen release capacity of 2.29 wt.%, a hydrogen absorption plateau of 1.3 MPa, and a hydrogen release plateau of 0.47 MPa.

[0071] Comparative Example 1

[0072] This embodiment prepares a high-entropy alloy with the same general chemical formula as Example 1. The chemical formula of the alloy is the same as that of Example 1, except that the preparation process is different. The preparation process of this comparative example is carried out according to the arc melting method in the literature: HZHu, CMMa, L. Zhou, HQXiao, QJChen, Understanding crystal structure roles towards developing high-performance V-free BCC hydrogen storage alloys, International Journal of Hydrogen Energy, 2022, 47:25335-25346. The specific process is as follows:

[0073] (1) According to the chemical composition Ti 0.4 Cr 0.45 Mo 0.10 Mn 0.05 The materials are batched, and Ti, Cr, Mo, and Mn elements are directly co-melted during the smelting process. The smelting is carried out 4 times. Finally, a copper mold is used for suction casting to obtain a suction casting alloy with a diameter of 2mm.

[0074] (2) The suction-cast alloy was crushed in air and ball-milled into powder to 100 mesh. The hydrogen storage performance of the alloy was determined by Sievert's method.

[0075] Comparative Example 2

[0076] This comparative example prepared a high-entropy alloy with the same general chemical formula as in Example 1. Two groups of samples, A and B, were prepared respectively. The chemical formula of the alloy was the same as in Example 1, and the preparation method was similar to that in Example 1. The only difference was that the heat treatment process was different during the preparation process, as detailed below.

[0077] Group A: The alloy sample was directly heated from room temperature to 1450℃ at a rate of 5℃ / min and held at that temperature for 2 hours.

[0078] Group B: The alloy sample was heated from room temperature to 1450℃ at a heating rate of 1℃ / min and held at that temperature for 2 hours.

[0079] The products prepared from groups A and B of Comparative Examples 1 and 2 were subjected to a series of performance tests, and the specific results are as follows.

[0080] Test results show that

[0081] The alloy prepared in Comparative Example 1 is not a BCC-type single-phase structure, but also contains 10% Laves phase structure and 5% Ti segregated phase; the alloy has a hydrogen storage capacity of 3.05 wt.%, a hydrogen release capacity of 1.83 wt.%, a hydrogen absorption plateau of 1.81 MPa, and a hydrogen release plateau of 0.41 MPa.

[0082] The alloy prepared in Group A of Comparative Example 2 is not a BCC type single-phase structure, but also contains 17% Laves phase structure; the alloy has a hydrogen storage capacity of 2.64 wt.%, a hydrogen release capacity of 1.67 wt.%, a hydrogen absorption plateau of 1.5 MPa, and a hydrogen release plateau of 1.07 MPa.

[0083] The alloy prepared in Group B of Comparative Example 2 is not a BCC type single-phase structure, but contains 25% Laves phase structure and 15% Ti segregated phase; the alloy has a hydrogen storage capacity of 2.01 wt.%, a hydrogen release capacity of 1.42 wt.%, a hydrogen absorption plateau of 1.6 MPa, and a hydrogen release plateau of 1.1 MPa.

[0084] Comparative Example 3

[0085] This comparative example prepares a high-entropy alloy with the same general chemical formula as Example 1. The chemical formula of the alloy is the same as that of Example 1, and the preparation method is similar to that of Example 1. The only difference is that the cooling method after heat treatment is different, as detailed below.

[0086] The alloy sample was heated from room temperature to 1000℃ at a rate of 5℃ / min, and then heated to 1450℃ at a rate of 1℃ / min, and held at that temperature for 2 hours.

[0087] After the heat preservation was completed, the alloy sample was allowed to cool naturally in the furnace to obtain a high-entropy alloy.

[0088] The product prepared in Comparative Example 3 underwent a series of performance tests, and the specific results are as follows.

[0089] Test results show that

[0090] The alloy prepared in Comparative Example 3 is not a BCC-type single-phase structure, but also contains 10% Laves phase structure and 11% Ti-Fe segregated phase; the alloy has a hydrogen storage capacity of 3.11 wt.%, a hydrogen release capacity of 1.92 wt.%, a hydrogen absorption plateau of 1.69 MPa, and a hydrogen release plateau of 0.38 MPa.

[0091] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A single phase high entropy hydrogen storage alloy, characterized in that, The chemical composition general formula is Ti x Cr y Mo z M r , wherein: x , y , z , r is an atomic ratio, 0.35≤ x ≤0.55, 0.35≤ y ≤0.55, 0.02≤ z ≤0.15, 0.02≤ r ≤0.15, and the M is Mn or Fe; the hydrogen storage alloy is a BCC type body-centered cubic single-phase structure, and the phase abundance is 100%. The preparation method of the single-phase high-entropy hydrogen storage alloy is sequentially performed according to the following steps: (1) ingredients are prepared according to the element proportion of the general chemical composition formula of the high-entropy hydrogen storage alloy, and then arc melting is performed; in the melting process, Cr and Mo metal elements are first melted into intermetallic compounds, and then melted together with other metal elements to obtain a cast alloy; (2) the cast alloy is placed in a quartz tube, the quartz tube is then vacuumized and inert gas is introduced, and then the quartz tube is sealed, and heat treatment is performed under the protection of 0.04 MPa argon atmosphere; The heat treatment adopts a segmented heating process, when the temperature is lower than 1000℃, the heating rate is 5-15℃ / min; then the temperature continues to rise to 1250-1400℃ at a heating rate of 1-2℃ / min, and the temperature is kept for 2-6h; (3) the quartz tube containing the heat-treated alloy is taken out, and then water quenching treatment is performed in water at 25℃, the water quenching treatment time is 1min, and the single-phase high-entropy hydrogen storage alloy is obtained.

2. The single-phase high-entropy hydrogen storage alloy of claim 1, wherein, In step (1), the melting current is 100-300A, the melting time is 300s / time, and the melting times is 4-6 times.

3. The single-phase high-entropy hydrogen storage alloy according to claim 1 or 2, characterized in that, The high-entropy hydrogen storage alloy has a hydrogen absorption amount of ≥3.24wt.%, a hydrogen release amount of ≥2.07wt.%, and a hydrogen release platform pressure value of ≥0.25MPa.

Images