Alfe nitiv high-entropy alloy material and preparation method thereof

Abstract

This invention provides an AlFeNiTiV high-entropy alloy material and its preparation method. The composition of the high-entropy alloy material is Al 15 Fe x Ni 30 Ti 15 V 40‑x Where 30≤x≤40. The technical solution of the present invention obtains AlFeNiTiV high-entropy alloy material by appropriately adjusting the composition of BCC-(Fe,V) phase in the alloy. It has a synergistic enhancement effect of multiple strengthening methods such as solid solution strengthening, grain boundary strengthening, and second phase strengthening. While sacrificing a small density, it significantly improves the mechanical properties of the alloy, exhibiting excellent performance of low density, high strength, and excellent high-temperature specific yield strength.

Description

Technical Field

[0001] This invention relates to the field of materials technology, and in particular to an AlFeNiTiV high-entropy alloy material and its preparation method. Background Technology

[0002] Currently, traditional nickel-based superalloys widely used in gas turbines and aero engines have reached 80% of their melting point, which cannot meet the increasingly stringent operating conditions brought about by further increases in operating temperature. In addition, nickel-based superalloys also have the disadvantages of high price and high density. Therefore, there is an urgent need to develop a new generation of lightweight, high-strength, and low-cost structural alloys for high-temperature applications.

[0003] Currently, among the reported lightweight high-entropy alloys, based on elemental properties, their systems can be roughly divided into three categories: alloy systems mainly composed of conventional metallic elements Al, Co, Cr, Fe, and Ni; alloy systems containing one or more refractory metallic elements Nb, W, Mo, and Ta; and alloy systems containing ultra-low-density elements such as Mg and Li. Among these, the majority of high-entropy alloy systems mainly composed of Al, Mg, Li, Zn, and Ti have a density ≤ 4.5 g / cm³. 3 (Traditional titanium alloys), with a hardness ≥400HV, are currently the lightest high-entropy alloy systems with relatively high specific hardness and have been extensively studied by many scholars. However, the specific yield strength of the lightest high-entropy alloys prepared so far is generally low, which cannot further meet the needs of aerospace, energy and transportation fields that require lightweight and high-strength materials.

[0004] The presence of ordered or intermetallic phases contributes to the high strength of high-entropy alloys. In recent years, numerous studies have shown that the Ni2AlTi structure with a Huesler structure, as an ordered variant of the B2 structure, has become a prominent research focus due to its favorable properties, such as cost-effectiveness, low density, and excellent high-temperature creep resistance. However, while the finite-slip system of the L21 phase can enhance the alloy's properties, it also makes the alloy brittle at room temperature. Recently, some research reports have indicated that the L21+BCC dual-phase structure, with its similar crystal structure and lower lattice mismatch, has attracted considerable attention due to its excellent ductility and high-temperature performance. This structure not only maintains the high thermal stability of the L21 phase but also exhibits excellent strength at both room and high temperatures. However, the unclear rules governing its mechanical properties make it difficult to predict how to improve the alloy's mechanical properties, lacking a systematic guiding method and failing to flexibly adapt to the needs of different application environments.

[0005] In general, significant progress has been made in the development of lightweight, high-strength, and high-entropy alloys, but there are still some shortcomings and deficiencies: (1) There is still very little research on the high-temperature performance of lightweight high-entropy alloys, which needs further research and improvement. Judging from the current development trend of lightweight high-strength alloys, it is difficult to achieve a major breakthrough in the performance limits of traditional lightweight alloys. (2) Most lightweight high-entropy alloys exhibit BCC phase and multiphase structures, and have high room temperature brittleness. However, due to the lack of clear laws governing their mechanical properties and the absence of systematic guidance methods, their further applications are limited. Summary of the Invention

[0006] To address the above technical problems, this invention discloses an AlFeNiTiV high-entropy alloy material and its preparation method. By adjusting the appropriate composition, the synergistic reinforcement effect of the BCC-(Fe,V) phase and the L21-(Ni2AlTi) phase in the alloy is improved, and the performance of the L21-strengthened alloy is optimized, giving it a combination of low density, high strength, and excellent high-temperature specific yield strength, which has broad application prospects.

[0007] The technical solution adopted by this invention is as follows:

[0008] A high-entropy AlFeNiTiV alloy material, its composition is Al 15 Fe x Ni 30 Ti 15 V 40-x , where 30≤x≤40.

[0009] By adopting this technical solution and selecting appropriate components, the alloy material can improve the synergistic reinforcement effect of the BCC-(Fe,V) phase and L21-(Ni2AlTi) phase in the alloy, optimize the performance of L21-strengthened alloy, and make it exhibit a combination of low density, high strength and excellent high temperature specific yield strength, which has broad application prospects.

[0010] As a further improvement of the present invention, x = 35 or 40.

[0011] This invention also discloses a method for preparing the AlFeNiTiV high-entropy alloy material as described above, comprising the following steps:

[0012] Step S1, according to A1 15 Fe x Ni 30 Ti 15 V 40-x The nominal proportions of Al, Fe, Ni, Ti, and V particles were weighed, and alloy ingots were prepared by vacuum argon arc melting.

[0013] Step S2, when the vacuum degree reaches 5×10 -3When the pressure is below Pa, argon gas is introduced to a vacuum of -0.025 Pa, and the alloy ingot is remelted multiple times.

[0014] This technical solution is simple to prepare, and the synergistic enhancement effect of the BCC-(Fe,V) phase and L21-(Ni2AlTi) phase in the alloy can be improved by adjusting the composition appropriately.

[0015] As a further improvement of the present invention, in step S2, the material is remelted 5 times, with each remelting time being 3 minutes.

[0016] As a further improvement of the present invention, the welding current in the vacuum argon arc melting method is 230A.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] Using the technical solution of this invention, Al is used to design the composition of lightweight alloys in conjunction with the concept of high-entropy alloys. 15 Fe x Ni 30 Ti 15 V 40-x This lightweight high-entropy alloy, based on conventional lightweight alloy systems, removes the expensive element Co to reduce costs. Through appropriate compositional adjustments to the BCC-(Fe,V) phase in the alloy, it exhibits a synergistic strengthening effect from multiple strengthening mechanisms, including solid solution strengthening, grain boundary strengthening, and second-phase strengthening. While sacrificing a relatively low density, it significantly improves the alloy's mechanical properties, demonstrating excellent performance characterized by low density, high strength, and superior high-temperature specific yield strength. The Al in this invention... 15 Fe 35 Ni 30 Ti 15 V5 is a high-entropy alloy with a BCC+L21 two-phase structure and a semi-coherent interface between the two phases. This reduces the dislocation migration rate during deformation, ultimately resulting in a significant increase in yield strength while maintaining a relatively low density of 6.81 g / cm³. 3 Under these conditions, a room temperature yield strength of 2140 MPa and a specific yield strength of 314.4 MPa·cm were achieved. 3 It boasts excellent technical specifications of / g. Furthermore, Al 15 Fe 35 Ni 30 Ti 15 The V5 high-entropy alloy also exhibits excellent high-temperature mechanical properties, showing high compressive yield strength (1612 MPa and 972 MPa) and high compressive plasticity (25% and 33%) at 600 and 700 °C. Attached Figure Description

[0019] Figure 1 Al is a different x in the embodiments of the present invention.15 Fe x Ni 30 Ti 15 V 40-x SEM micrographs of high-entropy alloys; where (a)x=0, (b)x=10, (c)x=20, (d)x=30, (e)x=35, (f)x=40.

[0020] Figure 2 Al is a different x in the embodiments of the present invention. 15 Fe x Ni 30 Ti 15 V 40-x The phases of the alloy, wherein (a) is Al 15 Fe x Ni 30 Ti 15 V 40-x XRD patterns of alloys (x = 0, 10, 20, 30, 35 and 40%), (b) is a magnified view of the 2θ angle range in (a) between 42 and 46 degrees, and (c) is a plot of fitting the (110)BCC and (220)L21 peaks of alloys x = 10 and x = 30 using a pseudo Voigt function.

[0021] Figure 3 Al is a different x in the embodiments of the present invention. 15 Fe x Ni 30 Ti 15 V 40-x IPF diagrams of high-entropy alloys, where (a)x = 0, (b)x = 10, (c)x = 20, (d)x = 30, (e)x = 35, and (f)x = 40.

[0022] Figure 4 Al is a different x in the embodiments of the present invention. 15 Fe x Ni 30 Ti 15 V 40-x Density comparison chart of high-entropy alloys.

[0023] Figure 5 Al is a different x in the embodiments of the present invention. 15 Fe x Ni 30 Ti 15 V 40-x Hardness comparison chart of high-entropy alloys.

[0024] Figure 6 Al is a different x in the embodiments of the present invention. 15 Fe x Ni30 Ti 15 V 40-x Compressive stress-strain curves of high-entropy alloys.

[0025] Figure 7 Al is a different x in the embodiments of the present invention. 15 Fe x Ni 30 Ti 15 V 40-x Fracture morphology diagrams of high-entropy alloys; where (a)x=0, (b)x=20, (c)x=35, (d)x=40.

[0026] Figure 8 This is Al, an embodiment of the present invention. 15 Fe 35 Ni 30 Ti 15 High-temperature compressive stress-strain curves of V5 high-entropy alloy at 600-900℃.

[0027] Figure 9 This is Al, an embodiment of the present invention. 15 Fe 35 Ni 30 Ti 15 IPF and grain boundary diagrams of V5 high-entropy alloy deformed at high temperatures, where (a) and (a1) are IPF and grain boundary diagrams at 600℃, and (b) and (b1) are IPF and grain boundary diagrams at 800℃.

[0028] Figure 10 This is Al, an embodiment of the present invention. 15 Fe x Ni 30 Ti 15 V 40-x Vertical cross-sectional views of CCAs phase diagrams for alloys with different x values. Detailed Implementation

[0029] The preferred embodiments of the present invention will be described in further detail below.

[0030] A high-entropy AlFeNiTiV alloy material, its composition is Al 15 Fe x Ni 30 Ti 15 V 40-x (hereinafter referred to as AlFeNiTiV), wherein 30≤x≤40. Preparation methods include:

[0031] According to the nominal proportions, raw materials of Al, Fe, Ni, Ti, and V particles with a purity of 99.99 wt.% were selected. The alloy ingots with the designed composition were prepared using a vacuum argon arc melting method, with a vacuum degree of 5 × 10⁻⁶.-3 When the pressure is below Pa, argon gas is introduced to a vacuum of -0.025 Pa. To ensure chemical homogeneity, the alloy is remelted 5 times, with each remelting time being 3 minutes and the welding current being 230A.

[0032] Alloys with different values ​​of x were prepared using the above method, namely x = 0, 10, 20, 30, 35, and 40, which represent the at.% content of Fe.

[0033] Al under different Fe contents 15 Fe x Ni 30 Ti 15 V 40-x SEM morphology of alloy materials as follows Figure 1 As shown in the SEM images, the addition of Fe transforms the alloy's microstructure from a dendritic structure to a network structure. The alloy exhibits two phases with different contrasts in backscattered electron microscopy: a dark phase (rich in Al, Ni, Ti) and a bright phase (rich in Fe, V). When the Fe content is below 30 at.%, in addition to the above two phases, a bright white intermetallic compound, the Laves phase, is also found at the interface. The presence of the brittle Laves phase leads to crack initiation at the interface, resulting in a decrease in the alloy's mechanical properties. Figure 2 The images show the XRD patterns of high-entropy alloys with different Fe contents. The alloys are mainly composed of two phases: disordered BCC and ordered L21, corresponding to [missing information - likely a specific phase or structure]. Figure 1 The BCC phase exhibits both a rich (Fe, V) and a dark (Al, Ni, Ti) phase. With increasing Fe content, the diffraction peaks of the BCC phase shift to the right, and the lattice constant of the BCC phase decreases continuously. Furthermore, a brittle phase exists at Fe additions of 0 at.% and 10 at.%, corresponding to… Figure 1 The bright white phase (Fe and Ti-rich Laves phase) was observed. Due to the low content, the characteristic peaks of the Laves phase were not observed in the XRD of alloys with Fe additions of 20 at.% and 30 at.% Figure 3 For Al 15 Fe x Ni 30 Ti 15 V 40-x The IPF plot of the EBSD of the alloy material shows that as the Fe content increases, the alloy grains change from columnar dendrites to equiaxed grains. The equiaxed grains remain basically unchanged after continuous refinement. According to the Hall-Page formula, the continuous increase in the degree of grain refinement leads to a corresponding increase in the number of grain boundaries, and the strength gain effect brought by grain boundary strengthening is also enhanced. Figure 4 Al is given 15 Fe x Ni 30 Ti 15 V40-x The graph showing the change in density of the alloy material with increasing Fe content indicates that an increase in Fe content leads to a slight increase in alloy density, but it still falls within the definition of a lightweight, high-entropy alloy (7 g / cm³). 3 Within the range of ). Figure 5 For Al 15 Fe x Ni 30 Ti 15 V 40-x The hardness variation graph of the alloy material shows that the addition of Fe initially increases the hardness of the alloy, then decreases it, reaching its maximum value when the Fe addition amount is 35 at.%. Al 15 Fe x Ni 30 Ti 15 V 40-x The compressive stress-strain curve of the alloy material is as follows: Figure 6 As shown, with the continuous increase of Fe content, the gains from solid solution strengthening and grain boundary strengthening continuously increase. The yield strength of the alloy first increases and then decreases, while the plasticity shows a trend of first significantly decreasing and then increasing. When the Fe addition is 10 at.%, the presence of the Laves brittle phase causes a significant decrease in the alloy's plasticity, and the compressive fracture strength also decreases. Figure 7 SEM images of the compressive fracture surfaces with Fe additions of 0, 20, 35, and 40 at.% show that when the Fe addition is 0 at.%, the fracture surface has a large number of dimples, indicating ductile fracture. When the Fe addition is 20 at.%, the alloy fracture surface exhibits a river-like and cleavage step morphology, which is a typical brittle fracture characteristic. When the Fe addition increases to 35 at.%, the macroscopic morphology of the fracture surface shows typical intergranular fracture characteristics, and the microscopic images of the fracture surface show that there are also a small number of transgranular fracture characteristics. When the Fe addition is 40 at.%, cracks can be observed in the fracture surface, the fracture surface is relatively smooth and there are a small number of dimples, which is a fracture characteristic of ductile-brittle combination.

[0034] The present invention aims to obtain a lightweight high-entropy alloy with both excellent mechanical properties and low density. It utilizes a vacuum argon arc melting method to prepare and optimize an AlFeNiTiV-based lightweight high-entropy alloy. The optimal Fe content is selected based on the mechanical properties of the as-cast alloy, and Al content is chosen within the defined density range for lightweight high-entropy alloys. 15 Fe 35 Ni 30 Ti 15 V5 high-entropy alloy is the optimal composition.

[0035] The results show that, under the synergistic effect of BCC and L21, Al 15 Fe 35 Ni 30 Ti15 The density of V5 high-entropy alloy is 6.81 g / cm³. 3 The compressive yield strength and plasticity are 2140 MPa and 6.7%, respectively, and the specific yield strength is as high as 314.4 MPa·cm. 3 The alloy with this composition achieves a combination of low density and excellent mechanical properties. High-temperature compression tests were conducted on the alloy with this composition. Figure 8 For Al 15 Fe 35 Ni 30 Ti 15 The high-temperature compressive stress-strain curves of V5 high-entropy alloy at 600-900℃ are shown. When the test temperature is increased from room temperature to 600℃ and 700℃, the alloy's strength decreases while its deformability increases. The yield strengths are 1612 MPa and 972 MPa, respectively, with compressive plasticity reaching 25% and 33%. At 800℃, the yield strength further decreases to 536 MPa. At 900℃, the yield strength drops sharply to 196 MPa, and the strain exceeds 50% during compression without fracture, indicating that this alloy possesses excellent high-temperature mechanical properties.

[0036] In order to study the microstructure evolution during the high-temperature softening process, Figure 9 EBSD images of the central region of the cross-section of Fe35 alloy after compression fracture at two characteristic temperatures (600℃ and 800℃) are shown. Figure 9 It is evident that the grain size of the alloy slightly increases with increasing deformation temperature. No recrystallized grains were observed inside the alloy at 600℃, indicating that dynamic recovery still dominates within the alloy. A lower proportion of dynamic recrystallization (DRX) was observed in the microstructure of the alloy deformed at 800℃, but the high-temperature softening mechanism of the alloy remains primarily dynamic recovery. The presence of DRX reduces the deformation resistance of the metallic material and increases its plasticity, thereby leading to increased alloy ductility and decreased yield strength. It is noteworthy that Al... 15 Fe 35 Ni 30 Ti 15 The stress-strain curve of V5 alloy shows that the yield strength of the alloy decreases significantly at 900℃.

[0037] CALPHAD calculations classified Al into different components. 15 Fe x Ni 30 Ti 15 V 40-x The solidification path of the alloy was established, and Al was determined. 15 Fe x Ni 30 Ti 15 V 40-xThe vertical cross section of the phase diagram is as follows Figure 10 As shown. Al 15 Fe 35 Ni 30 Ti 15 The V5 alloy undergoes a BCC-FCC phase transformation at approximately 900°C, which may explain the significant decrease in yield strength at this high temperature.

[0038] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A high-entropy AlFeNiTiV alloy material, characterized in that: Its composition is Al 15 Fe x Ni 30 Ti 15 V 40-x , where 30≤x≤40.

2. The AlFeNiTiV high-entropy alloy material according to claim 1, characterized in that: x = 35 or 40.

3. The method for preparing the AlFeNiTiV high-entropy alloy material as described in claim 1 or 2, characterized in that: Includes the following steps: Step S1, according to A1 15 Fe x Ni 30 Ti 15 V 40-x The nominal proportions of Al, Fe, Ni, Ti, and V particles were weighed, and alloy ingots were prepared by vacuum argon arc melting. Step S2, when the vacuum degree reaches 5×10 -3 When the pressure is below Pa, argon gas is introduced to a vacuum of 0.025 Pa, and the alloy ingot is remelted multiple times.

4. The method for preparing the AlFeNiTiV high-entropy alloy material according to claim 3, characterized in that: In step S2, the material is remelted 5 times, with each remelting session lasting 3 minutes.

5. The method for preparing the AlFeNiTiV high-entropy alloy material according to claim 3, characterized in that: The welding current in the vacuum argon arc melting method is 230 A.

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