NiFeCr-based medium-entropy alloy with aging precipitation induced recrystallization and preparation method

Abstract

The application discloses a NiFeCr-based medium-entropy alloy with aging precipitation induced recrystallization, and the composition is Ni 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3, and the microstructure is composed of two phases of FCC and BCC. The preparation method of the NiFeCr-based medium-entropy alloy is as follows: the surfaces of Ni, Fe, Cr, Ti and Al metal raw materials are polished, cleaned and dried in sequence; the Ni, Fe, Cr, Ti and Al raw materials are weighed according to the atomic percentage; the metal raw materials are placed in an electric arc furnace for smelting; and the obtained medium-entropy alloy ingot is sequentially subjected to primary cold rolling, annealing, secondary cold rolling, annealing, tertiary cold rolling, annealing and aging treatment. The aging treatment promotes the precipitation of fine BCC phase in the FCC phase, and the recrystallization is driven by the strain field near the precipitate phase interface, so that the FCC grains can be further refined, thereby improving the yield strength of the alloy while maintaining good plasticity.

Description

Technical Field

[0001] This invention belongs to the field of medium-entropy alloy preparation technology, specifically relating to NiFeCr-based medium-entropy alloys induced by aging precipitation recrystallization, and also to a method for preparing the NiFeCr-based medium-entropy alloy. Background Technology

[0002] Medium / high entropy alloys or multi-principal element alloys have attracted widespread attention in the field of structural materials due to their unique compositional design concepts and excellent mechanical properties. Among them, medium-entropy alloys with FCC structures, such as CoCrFeNi, CoFeNi, CoCrNi, and CrFeNi, exhibit good phase stability and plasticity (Z. Wu, H. Bei, GM Pharr, EP George, ActaMater. 81 (2014) 428-441), but their relatively low strength limits their industrial applications. Therefore, strengthening medium-entropy alloys with FCC structures has received widespread attention. However, these alloys are highly dependent on cobalt, and the high cost and uneven distribution of cobalt resources make it difficult to achieve large-scale application in aerospace, transportation, and other industrial fields. Therefore, developing low-cost, cobalt-free or low-cobalt high-performance NiFeCr medium-entropy alloys has become a key direction for overcoming application bottlenecks.

[0003] To improve the yield strength of entropy alloys with FCC structure NiFeCr, researchers have explored a variety of strengthening strategies, including solid solution strengthening, precipitation strengthening, multiphase strengthening, and dislocation strengthening. Among them, the precipitation enhancement effect was most significant when L12 nanoparticles (KK Wen, XC Cai, SW Xin, BR Sun, R. Feng, CC Du, HHZhu, K. An, SJ Ding, FX Meng, Z. Yuan, Y. Wu, ZH Bai, PK Liaw, TDShen, Matter. 7 (2024) 3625-3644) or B2 nanoprecipitate phase (HW Hu, Y. Xu, SQ Ding, DX Zhang, J. Wang, JZ Jiang, XD Wang, QP Cao, Scr. Mater. 276 (2026)117190) were introduced by adding Ti or Al and combining it with thermomechanical treatment. Simultaneously, this treatment process usually also involves the formation of a certain amount of BCC second phase, thus introducing a multiphase enhancement effect (SQ Li, GQ Zu, HY Jia, MY Li, ZPXiong, WW Zhu, Y. Han, X. Ran, Y. Zhao, J. Alloys Compd. 1039). (2025)183082). Although the above-mentioned strengthening methods have achieved good results, the yield strength of the alloy has not yet reached the ideal level. Therefore, how to further introduce new mechanisms such as fine-grain strengthening on the basis of existing strengthening methods, synergistically improve the yield strength and maintain good plasticity matching, so as to fully explore the application potential of this alloy system, has become a key issue that urgently needs to be solved in current research. Summary of the Invention

[0004] The purpose of this invention is to provide a NiFeCr-based medium-entropy alloy that undergoes aging precipitation-induced recrystallization. By refining the grains through aging precipitation-induced recrystallization, the low yield strength of the alloy in the prior art is effectively solved.

[0005] Another object of the present invention is to provide a method for preparing NiFeCr-based medium-entropy alloys by aging precipitation-induced recrystallization.

[0006] The technical solution adopted in this invention is a NiFeCr-based medium-entropy alloy with aging precipitation-induced recrystallization, the alloy composition being Ni. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3; its microstructure consists of two phases, FCC and BCC.

[0007] Another technical solution adopted in this invention is a method for preparing NiFeCr-based medium-entropy alloys by aging precipitation-induced recrystallization, specifically as follows: Step 1: Grind, clean, and dry the surfaces of Ni, Fe, Cr, Ti, and Al metal raw materials in sequence; Step 2, according to Ni 42.6 Fe 24.6 Cr 16.4 Al 13.4 The atomic percentage of Ti3 is determined by weighing Ni, Fe, Cr, Ti, and Al raw materials. Step 3: Melt the metal raw material in an electric arc melting furnace to obtain Ni. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingot; Step 4: Perform the following treatments on the medium entropy alloy ingot in sequence: first cold rolling, annealing, second cold rolling, annealing, third cold rolling, annealing, and aging.

[0008] The invention is further characterized in that, Step 3 specifically involves: Step 3.1: Place the raw material weighed in Step 2 into the water-cooled copper crucible of the vacuum arc melting furnace, close the furnace chamber and evacuate it, then fill it with argon gas to form a protective atmosphere. Step 3.2: Arc melt the raw material in the water-cooled copper crucible at a current of 450-500A. After the raw material is completely melted, turn on the electromagnetic stirring and continue for 4-6 minutes, then cool and solidify to obtain the initial ingot. Step 3.3: Turn the initial ingot over in a water-cooled copper crucible, repeat the melting process in step 3.2 four times, and finally perform drop casting to obtain Ni. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingot.

[0009] In step 4, the thinning rate of the first cold rolling is 20%~40%. The thinning rate of the second cold rolling is 20%~40%; the thinning rate of the third cold rolling is 20%~40%. During the first annealing, the annealing temperature is 1050℃~1150℃, and the holding time is 10~30 min; during the second annealing, the annealing temperature is 1050℃~1150℃, and the holding time is 10~30 min; during the third annealing, the annealing temperature is 950℃~1050℃, and the holding time is 10~60 min. During the aging treatment: the aging temperature is 700℃~800℃, and the aging time is 0.5~2 h.

[0010] The beneficial effects of this invention are: The NiFeCr-based medium-entropy alloy prepared by this invention, exhibits a microstructure composed of two phases: FCC and BCC (FCC phase volume fraction 64.6%, BCC phase volume fraction 35.4%). The FCC phase itself recrystallizes during the initial annealing process. Aging treatment further promotes the precipitation of fine, semi-coherent BCC precipitates within the FCC phase. This semi-coherent interface, designed to coordinate mismatch strain, introduces significant local lattice distortion and elastic strain fields near the interface, thereby inducing dislocation multiplication and increasing the dislocation density around the interface. These high dislocation density regions introduced by the fine BCC precipitates store high deformation energy, providing an energy source and potential nucleation sites for recrystallization. During the thermal activation process of aging treatment, the dislocations around the precipitates are reorganized through climb, slip, and rearrangement, inducing recrystallization. This recrystallization process, driven by the strain field at the precipitate interface, further refines the FCC grains, thus improving the yield strength of the medium-entropy alloy while maintaining good plasticity. Attached Figure Description

[0011] Figure 1 Ni in Embodiment 1 and Comparative Example 1 of the present invention 42.6 Fe 24.6 Cr 16.4 Al 13.4 XRD pattern of Ti3 medium entropy alloy; Figure 2a Ni in Embodiment 1 of the present invention 42.6 Fe 24.6 Cr 16.4 Al 13.4 SEM images of the EBSD analysis region of Ti3 medium entropy alloy; Figure 2b Ni in Embodiment 1 of the present invention 42.6 Fe 24.6 Cr 16.4 Al 13.4 Inverse pole figure (IPF) of the region corresponding to the EBSD of Ti3 medium entropy alloy. Figure 2c Ni in Embodiment 1 of the present invention 42.6 Fe 24.6 Cr 16.4 Al 13.4 Phase distribution diagram of Ti3 medium entropy alloy; Figure 2d Ni in Embodiment 1 of the present invention 42.6 Fe 24.6 Cr 16.4 Al 13.4 Phase distribution diagram of superimposed grain boundaries in Ti3 medium-entropy alloy; Figure 2eNi in Embodiment 1 of the present invention 42.6 Fe 24.6 Cr 16.4 Al 13.4 A magnified view of the superimposed grain boundaries of a Ti3 medium-entropy alloy; Figure 2f Ni in Embodiment 1 of the present invention 42.6 Fe 24.6 Cr 16.4 Al 13.4 KAM (local orientation difference) diagrams of the FCC and BCC phases in Ti3 medium entropy alloys; Figure 2g Ni in Embodiment 1 of the present invention 42.6 Fe 24.6 Cr 16.4 Al 13.4 KAM value distribution diagram of FCC and BCC phases in Ti3 medium entropy alloy; Figure 2h Ni in Embodiment 1 of the present invention 42.6 Fe 24.6 Cr 16.4 Al 13.4 Grain boundary orientation angle distribution diagram of FCC and BCC phases in Ti3 medium entropy alloy; Figure 2i Ni in Embodiment 1 of the present invention 42.6 Fe 24.6 Cr 16.4 Al 13.4 Grain size distribution diagram of the FCC phase in Ti3 medium entropy alloy; Figure 3a Ni in Comparative Example 1 42.6 Fe 24.6 Cr 16.4 Al 13.4 SEM images of the EBSD analysis region of Ti3 medium entropy alloy; Figure 3b Ni in Comparative Example 1 42.6 Fe 24.6 Cr 16.4 Al 13.4 Inverse pole figure (IPF) of the region corresponding to the EBSD of Ti3 medium entropy alloy. Figure 3c Ni in Comparative Example 1 42.6 Fe 24.6 Cr 16.4 Al 13.4 Phase distribution diagram of Ti3 medium entropy alloy; Figure 3d Ni in Comparative Example 1 42.6 Fe 24.6 Cr 16.4 Al 13.4Phase distribution diagram of superimposed grain boundaries in Ti3 medium-entropy alloy; Figure 3e Ni in Comparative Example 1 42.6 Fe 24.6 Cr 16.4 Al 13.4 A magnified view of the superimposed grain boundaries of a Ti3 medium-entropy alloy; Figure 3f Ni in Comparative Example 1 42.6 Fe 24.6 Cr 16.4 Al 13.4 KAM (local orientation difference) diagrams of the FCC and BCC phases in Ti3 medium entropy alloys; Figure 3g Ni in Comparative Example 1 42.6 Fe 24.6 Cr 16.4 Al 13.4 KAM value distribution diagram of FCC and BCC phases in Ti3 medium entropy alloy; Figure 3h Ni in Comparative Example 1 42.6 Fe 24.6 Cr 16.4 Al 13.4 Grain boundary orientation angle distribution diagram of FCC and BCC phases in Ti3 medium entropy alloy; Figure 3i Ni in Comparative Example 1 42.6 Fe 24.6 Cr 16.4 Al 13.4 Grain size distribution diagram of the FCC phase in Ti3 medium entropy alloy; Figure 4a Ni in Comparative Example 1 42.6 Fe 24.6 Cr 16.4 Al 13.4 EBSD phase distribution diagram of Ti3 medium entropy alloy; Figure 4b Ni is from Example 1 42.6 Fe 24.6 Cr 16.4 Al 13.4 EBSD phase distribution diagram of Ti3 medium entropy alloy; Figure 4c Ni in Comparative Example 1 42.6 Fe 24.6 Cr 16.4 Al 13.4 EBSD phase distribution diagram of Ti3 medium-entropy alloy with superimposed small-angle grain boundaries; Figure 4d Ni in Comparative Example 1 42.6 Fe 24.6 Cr16.4 Al 13.4 Calculated phase diagram of FCC matrix phase alloy composition in Ti3 medium entropy alloy; Figure 4e Ni is from Example 1 42.6 Fe 24.6 Cr 16.4 Al 13.4 Local KAM diagram of BCC precipitates around the FCC phase in Ti3 medium-entropy alloy; Figure 5a This is a high-resolution image of the interface between the BCC precipitate phase and the FCC matrix phase in Embodiment 1 of the present invention; Figure 5b These are the interface composite diffraction spots of the BCC precipitate phase and the FCC matrix phase in Example 1 of this invention; Figure 6 Ni in Embodiment 1 and Comparative Example 1 of the present invention 42.6 Fe 24.6 Cr 16.4 Al 13.4 Tensile engineering stress-strain curves of Ti3 medium entropy alloy. Detailed Implementation

[0012] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0013] This invention relates to a NiFeCr-based medium-entropy alloy with aging precipitation-induced recrystallization, the alloy composition of which is Ni. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 (at.%) The method for preparing NiFeCr-based medium-entropy alloys induced by aging precipitation according to the present invention is specifically implemented according to the following steps: Step 1: Grind, clean, and dry the surfaces of the elemental metal raw materials Ni, Fe, Cr, Ti, and Al in sequence; Step 2, according to Ni 42.6 Fe 24.6 Cr 16.4 Al 13.4 The atomic percentage ratio of Ti3 is determined by weighing out the corresponding masses of Ni, Fe, Cr, Ti, and Al metal raw materials. Step 3: Place the metal raw material from Step 2 into an electric arc melting furnace for melting to obtain Ni. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingots; specifically: Step 3.1: Place the raw material weighed in Step 2 into the water-cooled copper crucible of the vacuum arc melting furnace, close the furnace chamber and evacuate it, then fill it with argon gas to form a protective atmosphere. Step 3.2: Arc melt the raw material in the water-cooled copper crucible with a melting current of 450~500 A; after the raw material is completely melted, turn on the electromagnetic stirring and continue for 4~6 minutes, then cool and solidify to obtain the first ingot. Step 3.3: Turn the initial ingot over in a water-cooled copper crucible, repeat the melting process in step 3.2 four times, and finally perform drop casting to obtain Ni in lath form with uniform microstructure. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingot; Step 4, Ni 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingots were subjected to a series of processes including cold rolling, annealing, cold rolling, annealing, cold rolling, annealing, and aging treatment to obtain NiFeCr-based medium-entropy alloys with aging precipitation-induced recrystallization.

[0014] The thinning rate of a single cold rolling is 20%~40%, and the subsequent annealing temperature is 1050℃~1150℃, with a holding time of 10~30min.

[0015] The thinning rate of the second cold rolling is 20%~40% (the thinning rate is calculated based on the thickness after the first cold rolling), and the subsequent annealing temperature is 1050℃~1150℃, and the holding time is 10~30min.

[0016] The thinning rate of the three cold rolling processes is 20%~40% (the thinning rate is calculated based on the thickness after the two cold rolling processes), and the subsequent annealing temperature is 950℃~1050℃, with a holding time of 10~60min.

[0017] During the aging process: the aging temperature is 700℃~800℃, and the aging time is 0.5~2h.

[0018] The NiFeCrAlTi alloy in this invention has low plasticity. To prevent cracks caused by excessive deformation in a single rolling process, three rolling processes are adopted, with a small rolling amount each time (20%~40%). Annealing and softening treatment is performed between each rolling process before the next rolling process, which can effectively suppress crack initiation.

[0019] Example 1 The method for preparing NiFeCr-based medium-entropy alloys induced by aging precipitation and recrystallization according to the present invention is as follows: Step 1: Grind, clean, and dry the surfaces of Ni, Fe, Cr, Ti, and Al raw materials in sequence; Step 2, according to Ni 42.6 Fe 24.6 Cr 16.4 Al 13.4 The atomic percentage ratio of Ti3 is determined by weighing out the corresponding masses of pure metal raw materials of Ni, Fe, Cr, Al, and Ti. Step 3: Place the pretreated raw material in an electric arc melting furnace for melting to obtain Ni. 42.6 Fe 24.6 Cr 16.4 Al 13.4 The Ti3 medium-entropy alloy ingot is specifically: Step 3.1: Place the weighed raw materials from Step 2 into the water-cooled copper crucible of the vacuum arc melting furnace, close the furnace chamber and evacuate it, then fill it with argon gas to form a protective atmosphere. Step 3.2: Arc melting of the raw material in the water-cooled copper crucible with a melting current of 450 A; after the raw material is completely melted, electromagnetic stirring is turned on and continued for 6 minutes, followed by cooling and solidification to obtain the first ingot. Step 3.3: Turn the initial ingot over in a water-cooled copper crucible, repeat the melting process in step 3.2 four times, and finally perform drop casting to obtain Ni in lath form with uniform microstructure. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingot.

[0020] Step 4: The medium-entropy alloy ingot is subjected to a series of processes, including cold rolling, annealing, cold rolling, annealing, cold rolling, annealing, and aging, to obtain a NiFeCr-based medium-entropy alloy with aging precipitation-induced recrystallization.

[0021] The thinning rate of the first cold rolling is 30%, and the subsequent annealing temperature is 1100℃ with a holding time of 20min.

[0022] The thinning rate of the second cold rolling is 30% (the thinning rate is calculated based on the thickness after the first cold rolling), and the subsequent annealing temperature is 1100℃, with a holding time of 20min.

[0023] The thinning rate of the three cold rolling processes is 30% (the thinning rate is calculated based on the thickness after the two cold rolling processes), and the subsequent annealing temperature is 1000℃ with a holding time of 30min.

[0024] During the aging process: the aging temperature is 750℃ and the aging time is 0.5h.

[0025] The NiFeCr-based medium-entropy alloy prepared by this invention, which is induced by aging precipitation and recrystallization, combined with... Figure 1 XRD results and Figure 2c Phase distribution diagram, Figure 2d The magnified view of the superimposed grain boundaries shows that the microstructure of the NiFeCr-based medium-entropy alloy in Example 1 consists of two phases, FCC and BCC (FCC phase volume fraction is 64.6%, BCC phase volume fraction is 35.4%), and there are a large number of BCC precipitates in the FCC matrix. The FCC phase has recrystallized during the previous annealing process, such as... Figure 3b , Figure 3d , Figure 3e , Figure 3h EBSD analysis of Comparative Example 1, which only underwent annealing, showed that the FCC grain size was 2.73 μm. Figure 3i ). Figure 4a and Figure 4b The images show enlarged views of the EBSD phase distribution in Comparative Example 1 and Example 1, respectively. It can be seen that the aging treatment promoted the further precipitation of more fine BCC precipitates in the FCC matrix phase. Figure 4d The calculated phase diagram for the FCC matrix alloy (Ni-38.34, Fe-30.26, Cr-21.4, Al-7.48, Ti-2.52 at.%) shows that the FCC matrix is ​​in a supersaturated state after annealing at 1000℃, and the subsequent aging treatment promotes the further precipitation of more fine BCC precipitates in the FCC matrix phase.

[0026] Figure 5a and Figure 5b The images show high-resolution images of the interface between the FCC matrix phase and the BCC precipitate phase, and the composite diffraction spots of the two phases, indicating that the BCC precipitate phase and the FCC matrix phase exhibit a semi-coherent relationship. BCC / / FCC and

[001] BCC / /

[011] FCC Such semi-coherent interfaces, characterized by lattice mismatch, typically introduce significant local lattice distortion and elastic strain fields near the interface, thereby inducing dislocation multiplication and leading to an increase in dislocation density in the region surrounding the interface. Figure 4e As shown in the KAM diagram, the KAM value around the BCC phase is relatively high; generally, a higher KAM value indicates a higher dislocation density. Therefore, these high dislocation density regions introduced by the fine BCC precipitates store high deformation energy, providing an energy source and potential nucleation sites for recrystallization. During the thermal activation process of aging treatment, the dislocations around the precipitates are reorganized through processes such as climb, slip, and rearrangement, thereby inducing recrystallization. This recrystallization process is driven by the strain field at the precipitate interface, which can further refine the FCC phase grains, with a grain size of 1.28 μm. Figure 2iAs shown. Furthermore, from Comparative Example 1 ( Figure 3d , Figure 3e ) and Example 1 ( Figure 2d , Figure 2e Phase diagrams of superimposed grain boundaries and Comparative Example 1 ( Figure 3b ) and Example 1 ( Figure 2b The inverse pole figure comparison shows that aging treatment significantly refined the FCC grains, thereby increasing the alloy's yield strength to 1305 MPa while maintaining a good level of 7.8% plasticity. Figure 6 ).

[0027] Comparative Example 1 The preparation method of NiFeCr-based medium-entropy alloys (annealing only, without aging treatment) is as follows: Step 1: Grind, clean, and dry the surfaces of Ni, Fe, Cr, Ti, and Al raw materials in sequence; Step 2, according to Ni 42.6 Fe 24.6 Cr 16.4 Al 13.4 The atomic percentage ratio of Ti3 is determined by weighing out the corresponding masses of pure metal raw materials of Ni, Fe, Cr, Al, and Ti. Step 3: Place the pretreated raw material in an electric arc melting furnace for melting to obtain Ni. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingots; specifically: Step 3.1: Place the weighed raw materials from Step 2 into the water-cooled copper crucible of the vacuum arc melting furnace, close the furnace chamber and evacuate it, then fill it with argon gas to form a protective atmosphere. Step 3.2: Arc melting of the raw material in the water-cooled copper crucible with a melting current of 500 A; after the raw material is completely melted, electromagnetic stirring is turned on and continued for 4 minutes, followed by cooling and solidification to obtain the first ingot. Step 3.3: Turn the initial ingot over in a water-cooled copper crucible, repeat the melting process in step 3.2 four times, and finally perform drop casting to obtain Ni in lath form with uniform microstructure. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingot.

[0028] Step 4: The medium-entropy alloy ingot is subjected to a series of cold rolling, annealing, cold rolling, annealing, cold rolling, and annealing processes to obtain the annealed NiFeCr-based medium-entropy alloy.

[0029] The thinning rate of the first cold rolling is 30%, and the subsequent annealing temperature is 1100℃ with a holding time of 20min.

[0030] The thinning rate of the second cold rolling is 30% (the thinning rate is calculated based on the thickness after the first cold rolling), and the subsequent annealing temperature is 1100℃, with a holding time of 20min.

[0031] The thinning rate of the three cold rolling processes is 30% (the thinning rate is calculated based on the thickness after the two cold rolling processes), and the subsequent annealing temperature is 1000℃ with a holding time of 30min.

[0032] In Comparative Example 1, the final state of the NiFeCr-based medium-entropy alloy was the annealed state. Figure 1 XRD results and Figure 3c The EBSD phase analysis results show that the microstructure of the NiFeCr-based medium-entropy alloy in Comparative Example 1 also consists of two phases, FCC and BCC (FCC phase volume fraction is 67%, BCC phase volume fraction is 33%), and there is a relatively large amount of BCC precipitate in the annealed FCC matrix (it should be noted that the aging treatment in Example 1 further promotes the precipitation of more BCC phase in the FCC matrix). The alloy composition of the FCC matrix is ​​Ni-38.34, Fe-30.26, Cr-21.4, Al-7.48, Ti-2.52 at.%. The FCC phase itself underwent recrystallization during the annealing process (see...). Figure 3b , Figure 3d , Figure 3e , Figure 3h (EBSD analysis diagram in the image), the FCC grain size in Comparative Example 1 is 2.73 μm ( Figure 3i The grain size is larger than that of the FCC grains after aging treatment in Example 1 (1.28 μm, see Example 1). Figure 2i Correspondingly, the yield strength of the NiFeCr-based medium-entropy alloy in Comparative Example 1 was 802 MPa, significantly lower than the 1305 MPa in Example 1. Figure 6 ).

[0033] also, Figure 2a This is the EBSD analysis region of the NiFeCr-based medium-entropy alloy in Example 1. Figure 2f The KAM diagram of the NiFeCr-based medium-entropy alloy in Example 1 is used to characterize the distribution of dislocation density in the alloy. Figure 2g KAM values ​​for the FCC and BCC phases in the alloy of Example 1 represent the dislocation density. Figure 2h The grain boundary orientation angle distribution of the FCC and BCC phases in the alloy of Example 1 is shown to characterize whether recrystallization has occurred. Figure 3a The EBSD analysis region is shown for the NiFeCr-based medium-entropy alloy in Comparative Example 1. Figure 3f The KAM diagram of the NiFeCr-based medium-entropy alloy in Comparative Example 1 is shown, used to characterize the distribution of dislocation density in the alloy. Figure 3gKAM values ​​for the FCC and BCC phases in the alloy of Comparative Example 1 represent the dislocation density. Figure 4c The EBSD phase diagram of the comparative alloy 1 with small-angle grain boundaries superimposed shows that a small number of subgrain boundaries exist in the FCC phase.

[0034] Example 2 The method for preparing NiFeCr-based medium-entropy alloys induced by aging precipitation according to the present invention is specifically implemented according to the following steps: Step 1: Grind, clean, and dry the surfaces of the elemental metal raw materials Ni, Fe, Cr, Ti, and Al in sequence; Step 2, according to Ni 42.6 Fe 24.6 Cr 16.4 Al 13.4 The atomic percentage ratio of Ti3 is determined by weighing out the corresponding masses of Ni, Fe, Cr, Ti, and Al metal raw materials. Step 3: Place the metal raw material from Step 2 into an electric arc melting furnace for melting to obtain Ni. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingots; specifically: Step 3.1: Place the raw material weighed in Step 2 into the water-cooled copper crucible of the vacuum arc melting furnace, close the furnace chamber and evacuate it, then fill it with argon gas to form a protective atmosphere. Step 3.2: Arc melting of the raw material in the water-cooled copper crucible with a melting current of 450A; after the raw material is completely melted, electromagnetic stirring is turned on and continued for 4 minutes, followed by cooling and solidification to obtain the first ingot. Step 3.3: Turn the initial ingot over in a water-cooled copper crucible, repeat the melting process in step 3.2 four times, and finally perform drop casting to obtain Ni. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingot; Step 4, Ni 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingots were subjected to a series of processes including cold rolling, annealing, cold rolling, annealing, cold rolling, annealing, and aging treatment to obtain NiFeCr-based medium-entropy alloys with aging precipitation-induced recrystallization.

[0035] The thinning rate of the first cold rolling is 20%, followed by annealing at 1050℃ for 10 minutes. The thinning rate of the second cold rolling is 20%, followed by annealing at 1050℃ for 10 minutes. The thinning rate of the third cold rolling is 20%, followed by annealing at 950℃ for 10 minutes. The aging temperature is 700℃, and the aging time is 2 hours.

[0036] Example 3 The method for preparing NiFeCr-based medium-entropy alloys induced by aging precipitation according to the present invention is specifically implemented according to the following steps: Step 1: Grind, clean, and dry the surfaces of the elemental metal raw materials Ni, Fe, Cr, Ti, and Al in sequence; Step 2, according to Ni 42.6 Fe 24.6 Cr 16.4 Al 13.4 The atomic percentage ratio of Ti3 is determined by weighing out the corresponding masses of Ni, Fe, Cr, Ti, and Al metal raw materials. Step 3: Place the metal raw material from Step 2 into an electric arc melting furnace for melting to obtain Ni. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingots; specifically: Step 3.1: Place the raw material weighed in Step 2 into the water-cooled copper crucible of the vacuum arc melting furnace, close the furnace chamber and evacuate it, then fill it with argon gas to form a protective atmosphere. Step 3.2: Arc melting of the raw material in the water-cooled copper crucible with a melting current of 480A; after the raw material is completely melted, electromagnetic stirring is turned on and continued for 5 minutes, followed by cooling and solidification to obtain the first ingot. Step 3.3: Turn the initial ingot over in a water-cooled copper crucible, repeat the melting process in step 3.2 four times, and finally perform drop casting to obtain Ni in lath form with uniform microstructure. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingot; Step 4, Ni 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingots were subjected to a series of processes including cold rolling, annealing, cold rolling, annealing, cold rolling, annealing, and aging treatment to obtain NiFeCr-based medium-entropy alloys with aging precipitation-induced recrystallization.

[0037] The thinning rate of the first cold rolling is 30%, followed by an annealing temperature of 1050℃ and a holding time of 20 min. The thinning rate of the second cold rolling is 20%, followed by an annealing temperature of 1150℃ and a holding time of 15 min. The thinning rate of the third cold rolling is 40%, followed by an annealing temperature of 950℃ and a holding time of 30 min. The aging temperature is 740℃, and the aging time is 1 h.

[0038] Example 4 The method for preparing NiFeCr-based medium-entropy alloys induced by aging precipitation according to the present invention is specifically implemented according to the following steps: Step 1: Grind, clean, and dry the surfaces of the elemental metal raw materials Ni, Fe, Cr, Ti, and Al in sequence; Step 2, according to Ni 42.6 Fe 24.6 Cr 16.4 Al 13.4 The atomic percentage ratio of Ti3 is determined by weighing out the corresponding masses of Ni, Fe, Cr, Ti, and Al metal raw materials. Step 3: Place the metal raw material from Step 2 into an electric arc melting furnace for melting to obtain Ni. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingots; specifically: Step 3.1: Place the raw material weighed in Step 2 into the water-cooled copper crucible of the vacuum arc melting furnace, close the furnace chamber and evacuate it, then fill it with argon gas to form a protective atmosphere. Step 3.2: Arc melting of the raw material in the water-cooled copper crucible with a melting current of 500 A; after the raw material is completely melted, electromagnetic stirring is turned on and continued for 6 minutes, followed by cooling and solidification to obtain the first ingot. Step 3.3: Turn the initial ingot over in a water-cooled copper crucible, repeat the melting process in step 3.2 four times, and finally perform drop casting to obtain Ni in lath form with uniform microstructure. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingot; Step 4, Ni 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingots were subjected to a series of processes including cold rolling, annealing, cold rolling, annealing, cold rolling, annealing, and aging treatment to obtain NiFeCr-based medium-entropy alloys with aging precipitation-induced recrystallization.

[0039] The thinning rate of the first cold rolling is 30%, followed by annealing at 1150℃ for 30 minutes. The thinning rate of the second cold rolling is 20%, followed by annealing at 1150℃ for 25 minutes. The thinning rate of the third cold rolling is 40%, followed by annealing at 1000℃ for 30 minutes. The aging temperature is 800℃, and the aging time is 0.5 hours.

[0040] Example 5 The method for preparing NiFeCr-based medium-entropy alloys induced by aging precipitation according to the present invention is specifically implemented according to the following steps: Step 1: Grind, clean, and dry the surfaces of the elemental metal raw materials Ni, Fe, Cr, Ti, and Al in sequence; Step 2, according to Ni 42.6 Fe 24.6 Cr 16.4 Al 13.4 The atomic percentage ratio of Ti3 is determined by weighing out the corresponding masses of Ni, Fe, Cr, Ti, and Al metal raw materials. Step 3: Place the metal raw material from Step 2 into an electric arc melting furnace for melting to obtain Ni. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingots; specifically: Step 3.1: Place the raw material weighed in Step 2 into the water-cooled copper crucible of the vacuum arc melting furnace, close the furnace chamber and evacuate it, then fill it with argon gas to form a protective atmosphere. Step 3.2: Arc melting of the raw material in the water-cooled copper crucible with a melting current of 450A; after the raw material is completely melted, electromagnetic stirring is turned on and continued for 6 minutes, followed by cooling and solidification to obtain the first ingot. Step 3.3: Turn the initial ingot over in a water-cooled copper crucible, repeat the melting process in step 3.2 four times, and finally perform drop casting to obtain Ni in lath form with uniform microstructure. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingot; Step 4, Ni 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingots were subjected to a series of processes including cold rolling, annealing, cold rolling, annealing, cold rolling, annealing, and aging treatment to obtain NiFeCr-based medium-entropy alloys with aging precipitation-induced recrystallization.

[0041] The thinning rate of the first cold rolling is 20%, followed by annealing at 1150℃ for 30 minutes. The thinning rate of the second cold rolling is 20%, followed by annealing at 1150℃ for 10 minutes. The thinning rate of the third cold rolling is 20%, followed by annealing at 1050℃ for 40 minutes. The aging temperature is 800℃, and the aging time is 2 hours.

[0042] Example 6 The method for preparing NiFeCr-based medium-entropy alloys induced by aging precipitation according to the present invention is specifically implemented according to the following steps: Step 1: Grind, clean, and dry the surfaces of the elemental metal raw materials Ni, Fe, Cr, Ti, and Al in sequence; Step 2, according to Ni 42.6 Fe 24.6 Cr 16.4 Al 13.4 The atomic percentage ratio of Ti3 is determined by weighing out the corresponding masses of Ni, Fe, Cr, Ti, and Al metal raw materials. Step 3: Place the metal raw material from Step 2 into an electric arc melting furnace for melting to obtain Ni. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingots; specifically: Step 3.1: Place the raw material weighed in Step 2 into the water-cooled copper crucible of the vacuum arc melting furnace, close the furnace chamber and evacuate it, then fill it with argon gas to form a protective atmosphere. Step 3.2: Arc melting of the raw material in the water-cooled copper crucible with a melting current of 500A; after the raw material is completely melted, electromagnetic stirring is turned on and continued for 6 minutes, followed by cooling and solidification to obtain the first ingot. Step 3.3: Turn the initial ingot over in a water-cooled copper crucible, repeat the melting process in step 3.2 four times, and finally perform drop casting to obtain Ni in lath form with uniform microstructure. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingot; Step 4, Ni 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingots were subjected to a series of processes including cold rolling, annealing, cold rolling, annealing, cold rolling, annealing, and aging treatment to obtain NiFeCr-based medium-entropy alloys with aging precipitation-induced recrystallization.

[0043] The thinning rate of the first cold rolling is 40%, followed by annealing at 1150℃ for 30 minutes. The thinning rate of the second cold rolling is 20%, followed by annealing at 1150℃ for 10 minutes. The thinning rate of the third cold rolling is 40%, followed by annealing at 1050℃ for 30 minutes. The aging temperature is 700℃, and the aging time is 2 hours.

Claims

1. A NiFeCr-based medium-entropy alloy with aging precipitation-induced recrystallization, characterized in that, The alloy composition is Ni 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3; its microstructure consists of two phases, FCC and BCC.

2. The method for preparing NiFeCr-based medium-entropy alloys by aging precipitation-induced recrystallization as described in claim 1, characterized in that, Specifically: Step 1: Grind, clean, and dry the surfaces of Ni, Fe, Cr, Ti, and Al metal raw materials in sequence; Step 2, according to Ni 42.6 Fe 24.6 Cr 16.4 Al 13.4 The atomic percentage of Ti3 is determined by weighing Ni, Fe, Cr, Ti, and Al raw materials. Step 3: Melt the metal raw material in an electric arc melting furnace to obtain Ni. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingot; Step 4: Perform the following treatments on the medium entropy alloy ingot in sequence: first cold rolling, annealing, second cold rolling, annealing, third cold rolling, annealing, and aging.

3. The method for preparing NiFeCr-based medium-entropy alloys by age-induced recrystallization as described in claim 2, characterized in that, Step 3 specifically involves: Step 3.1: Place the raw material weighed in Step 2 into the water-cooled copper crucible of the vacuum arc melting furnace, close the furnace chamber and evacuate it, then fill it with argon gas to form a protective atmosphere. Step 3.2: Arc melt the raw material in the water-cooled copper crucible. After the raw material is completely melted, turn on the electromagnetic stirring and continue for 4 to 6 minutes. Then cool and solidify to obtain the first ingot. Step 3.3: Turn the initial ingot over in a water-cooled copper crucible, repeat the melting process in step 3.2 four times, and finally perform drop casting to obtain Ni. 42.6 Fe 24.6 Cr 16.4 Al 13.4 Ti3 medium-entropy alloy ingot.

4. The method for preparing NiFeCr-based medium-entropy alloys by age-induced recrystallization as described in claim 3, characterized in that, In step 3.2, the smelting current is 450~500A.

5. The method for preparing NiFeCr-based medium-entropy alloys by age-induced recrystallization as described in claim 2, characterized in that, In step 4, the thinning rate of a single cold rolling is 20% to 40%.

6. The method for preparing NiFeCr-based medium-entropy alloys by aging precipitation-induced recrystallization as described in claim 5, characterized in that, In step 4, the thinning rate of the second cold rolling is 20%~40%; the thinning rate of the third cold rolling is 20%~40%.

7. The method for preparing NiFeCr-based medium-entropy alloys by aging precipitation-induced recrystallization as described in claim 2, characterized in that, In step 4, the first annealing is performed at a temperature of 1050℃~1150℃ and a holding time of 10~30min; the second annealing is performed at a temperature of 1050℃~1150℃ and a holding time of 10~30min; the third annealing is performed at a temperature of 950℃~1050℃ and a holding time of 10~60min.

8. The method for preparing NiFeCr-based medium-entropy alloys by aging precipitation-induced recrystallization as described in claim 2, characterized in that, In step 4, during the aging process: the aging temperature is 700℃~800℃, and the aging time is 0.5~2h.

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