A short process preparation method of a low yield ratio dual-phase high-entropy alloy

Abstract

This invention discloses a short-process preparation method for a low yield strength ratio dual-phase high-entropy alloy, comprising the following steps: melting prepared alloying elements to obtain a dual-phase high-entropy alloy ingot; heating and holding the dual-phase high-entropy alloy ingot, followed by quenching, to obtain the low yield strength ratio dual-phase high-entropy alloy. This invention employs a one-step heat treatment method that further improves the tensile strength of the dual-phase high-entropy alloy ingot while reducing its yield strength, effectively lowering the yield strength ratio of the dual-phase high-entropy alloy. Compared with rolling annealing or multi-stage heat treatment processes, it has the advantages of a shorter process, higher efficiency, and lower cost, making it suitable for industrial application.

Description

Technical Field

[0001] This invention relates to the field of alloy preparation technology, specifically to a short-process preparation method for low yield strength ratio dual-phase high entropy alloys. Background Technology

[0002] High-entropy alloys, through the rational design of the composition and proportion of various main elements, reduce the tendency for the formation of intermediate phases and improve the stability of simple solid solution phases. Their unique microstructure characteristics and the exhibited "high-entropy effect," "hysteresis diffusion effect," "lattice distortion effect," and "cocktail effect" endow them with excellent mechanical properties, such as high hardness, high strength, high temperature resistance, corrosion resistance, and radiation resistance, making them promising new high-performance metallic structural materials. Among them, FCC-type high-entropy alloys possess excellent plasticity and fracture toughness, but their strength is generally lower than that of BCC-type high-entropy alloys; BCC-type high-entropy alloys have high strength, wear resistance, and good high-temperature stability, but their low elongation is the main factor limiting their application. To achieve a good balance between strength and plasticity, two-phase and multi-phase high-entropy alloys achieve a significant improvement in overall performance through the synergistic effect of multiple strengthening mechanisms, such as the widely used Al... 0.7 CoCrFeNi. Industrially, to reduce costs, high-entropy alloys are typically prepared using arc melting, induction melting, or suspension melting. However, the multi-principal-element composition leads to severe compositional and microstructural segregation, which in turn affects the properties of high-entropy alloys, such as Al alloys prepared by current industrial melting. 0.7 The yield strength ratio of CoCrFeNi dual-phase high-entropy alloys is typically 60%-70%, which is insufficient to meet the safety requirements of components in service environments involving impact and vibration.

[0003] Therefore, while improving the fracture strength of the smelting and preparation of dual-phase high-entropy alloys, further reducing their yield strength ratio can simultaneously enhance the effective buffering capacity and overload resistance, which is of great practical significance for ensuring the safety and reliability of the components in service. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention presents a short-process preparation method for low yield strength ratio dual-phase high-entropy alloys.

[0005] To achieve the above-mentioned technical effects, the present invention is implemented through the following technical solution: a short-process preparation method for a low yield strength ratio dual-phase high-entropy alloy, characterized by comprising the following steps:

[0006] S1. Prepare Al, Co, Cr, Fe, and Ni materials; and weigh each material according to the element types and designed molar ratios of any alloy shown in (1)-(5) below.

[0007] (1) Al xCoCrFeNi, 0.5≤x≤0.9, and the molar ratio of any two elements in the other element content is 1:1;

[0008] (2) AlCo x CrFeNi, 2.0≤x≤5.0, and the molar ratio of any two elements in the other elements content is 1:1;

[0009] (3) AlCoCr x FeNi, x≤1.0, the molar ratio of any two elements in the other element content is 1:1;

[0010] (4) AlCoCrFe x Ni, 0.2≤x<0.6, and the molar ratio of any two elements in the other element content is 1:1;

[0011] (5) AlCoCrFeNi x 1.5≤x<3.0, and the molar ratio of any two elements in the other element content is 1:1;

[0012] The weighed alloy mixture is then placed into a muffle furnace for melting to obtain a dual-phase high-entropy alloy ingot.

[0013] S2. Place the dual-phase high-entropy alloy ingot into a resistance furnace and heat it to 600-1300℃ at a heating rate of 2-20℃ / min.

[0014] S3. When heating to 600-1300℃, stop heating and allow the high-entropy alloy ingot to be held in a resistance furnace at 600-1300℃ for 0.5-36 hours.

[0015] S4. After the heat treatment is completed, the high-entropy alloy ingot is placed in the quenching medium for quenching to obtain CoCrFeNiAl. x A series of low yield strength ratio dual-phase high entropy alloys.

[0016] Furthermore, the highest temperature inside the resistance furnace during heating is 900–1250°C.

[0017] Furthermore, the heat preservation treatment time is 1 to 3 hours.

[0018] Furthermore, the heating rate of the resistance furnace is 5–10 °C / min.

[0019] Furthermore, the smelting process employs one of the industrially common methods: electric arc melting, induction melting, or suspension melting.

[0020] Furthermore, the resistance furnace is a conventional air resistance furnace or a vacuum resistance furnace.

[0021] Furthermore, the quenching medium is a water-based or oil-based coolant.

[0022] Furthermore, the Al, Co, Cr, Fe, and Ni materials are all in the form of blocks, flakes, or filaments.

[0023] The beneficial effects of this invention are:

[0024] Compared with current rolling annealing or multi-stage heat treatment processes, the preparation method described in this invention can control the phase ratio and the size and distribution of precipitated phases in one step. It does not require vacuum heating, has a short process, and only requires one quenching treatment, which greatly shortens the production cycle. It can achieve the preparation of low yield strength ratio dual-phase high-entropy alloys with high efficiency and low cost, and further improve the tensile strength of dual-phase high-entropy alloys, reduce their yield strength, and effectively reduce the yield strength ratio. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 For suspension smelting of Al 0.7 Comparison of microstructure and phase content of CoCrFeNi dual-phase high-entropy alloy ingot after heating to 1000℃ and holding for 1 hour by the process of this invention and water quenching.

[0027] Figure 2 For suspension smelting of Al 0.7 Microstructure and phase content distribution of CoCrFeNi dual-phase high-entropy alloy ingot after being heated to 1000℃ and held for 2 hours by the process of this invention and then water quenched.

[0028] Figure 3 For suspension smelting of Al 0.7 Microstructure and phase content distribution of CoCrFeNi dual-phase high-entropy alloy ingot after being heated to 1000℃ and held for 3 hours by the process of this invention and then water quenched.

[0029] Figure 4 For suspension smelting of Al 0.7 Microstructure and phase content distribution of CoCrFeNi dual-phase high-entropy alloy ingot after being heated to 1050℃ and held for 3 hours by the process of this invention and then water quenched.

[0030] Figure 5 For suspension smelting of Al 0.7 Microstructure and phase content distribution of CoCrFeNi dual-phase high-entropy alloy ingot after being heated to 1150℃ and held for 3 hours by the process of this invention and then water quenched.

[0031] Figure 6 For suspension smelting of Al 0.7 Microstructure and phase content distribution of CoCrFeNi dual-phase high-entropy alloy ingot after being heated to 1250℃ and held for 3 hours by the process of this invention and then water quenched.

[0032] Figure 7 For suspension smelting of Al 0.7 A comparison of the true stress-true stress curves of CoCrFeNi dual-phase high-entropy alloy ingots and those quenched by water at different temperatures and holding times using the process of this invention. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Example 1

[0035] All embodiments in this invention involve smelting Al. 0.7 CoCrFeNi dual-phase high-entropy alloy ingot.

[0036] Conventional comparative example: Suspension melting of Al 0.7 The CoCrFeNi dual-phase high-entropy alloy ingot has a yield strength of 745 MPa, a tensile strength of 1115 MPa, and a yield-to-tensile ratio of 66.8%.

[0037] Example 2

[0038] Al is prepared using the short-process preparation method for low yield strength ratio dual-phase high entropy alloys described in this invention. 0.7 The CoCrFeNi dual-phase high-entropy alloy is as follows:

[0039] Al is smelted in a conventional muffle furnace 0.7 The CoCrFeNi dual-phase high-entropy alloy ingot was heated to 1000℃, held for 1 hour, and then water-quenched. The vermicular and basketweave regions in the original as-cast alloy disappeared, and a feather-like structure appeared. The B2 phase precipitated in the FCC phase. The yield strength was 610 MPa, the tensile strength was 1421 MPa, and the yield-to-tensile ratio decreased to 42.9%. The strength increased by 27.4%, and the yield-to-tensile ratio decreased by 35.8%.

[0040] Figure 1 For the original smelting of Al 0.7The microstructure and phase content comparison diagram of CoCrFeNi dual-phase high-entropy alloy ingots after heating to 1000℃ and holding for 1 hour and then water quenching using the process of this invention is shown. The original microstructure consists of anhedral FCC phase and a basketweave structure composed of vermicular or noodle-like structures and BCC / B2 phases, with FCC and BCC phases accounting for 70.4% and 29.6%, respectively. After water quenching at 1000℃ for 1 hour, the FCC phase decreased to 58.3%, the vermicular and basketweave regions disappeared, and a feather-like microstructure appeared; the BCC phase increased to 41.7%. The changes in phase content and phase morphology are related to Al... 0.7 The main reasons for the increased tensile strength and decreased yield strength ratio of CoCrFeNi dual-phase high-entropy alloy.

[0041] Example 2

[0042] Al is prepared using the short-process preparation method for low yield strength ratio dual-phase high entropy alloys described in this invention. 0.7 The CoCrFeNi dual-phase high-entropy alloy is as follows:

[0043] Al is smelted in a conventional muffle furnace 0.7 The CoCrFeNi dual-phase high-entropy alloy ingot was heated to 1000℃, held for 2 hours, and then water-quenched. A feather-like microstructure appeared, with a small amount of B2 phase precipitating in the FCC phase. The alloy yield strength was 664 MPa, tensile strength was 1419 MPa, and the yield-to-tensile ratio decreased to 46.8%. The strength increased by 27.3%, while the yield-to-tensile ratio decreased by 30.0%.

[0044] Figure 2 For the original suspension smelting of Al 0.7 Microstructure and phase content distribution of CoCrFeNi dual-phase high-entropy alloy ingots after heating to 1000℃ for 2 hours and water quenching using the process of this invention. After water quenching at 1000℃ for 2 hours, the alloy microstructure shows an interlayered distribution of FCC and BCC phases with a feather-like structure. Compared to water quenching at 1000℃ for 1 hour, the content of B2 precipitates in FCC is reduced, but the average size of the B2 precipitates increases and the average interphase spacing decreases. The FCC and BCC phases account for 61.2% and 38.3%, respectively. The changes in phase content and morphology, precipitate size, and average interphase spacing are related to Al 0.7 The main reasons for the increased tensile strength and decreased yield strength ratio of CoCrFeNi dual-phase high-entropy alloy.

[0045] Example 3

[0046] Al is prepared using the short-process preparation method for low yield strength ratio dual-phase high entropy alloys described in this invention. 0.7 The CoCrFeNi dual-phase high-entropy alloy is as follows:

[0047] Al is smelted in a conventional muffle furnace 0.7The CoCrFeNi dual-phase high-entropy alloy ingot was heated to 1000℃, held for 3 hours, and then water-quenched. This resulted in a feather-like microstructure, with a further reduction in the B2 phase content precipitated in the FCC phase. The yield strength was 670 MPa, and the tensile strength was 1426 MPa. The strength increased by 27.9%, while the yield-to-tensile ratio decreased to 47.0%.

[0048] Figure 3 For the original smelting of Al 0.7 Microstructure and phase content distribution of CoCrFeNi dual-phase high-entropy alloy ingots after heating to 1000℃ for 3 hours and water quenching using the process of this invention. After water quenching at 1000℃ for 3 hours, the alloy microstructure shows a layered distribution of FCC and BCC phases, with a feather-like structure still present. The content of B2 phase precipitated in the FCC phase is slightly less than that after 2 hours of quenching, and its average phase size and average interphase spacing are slightly increased. The FCC and BCC phases account for 62.7% and 37.3%, respectively. The changes in phase content and morphology are still mainly Al. 0.7 The main reasons for the increase in tensile strength and decrease in yield strength ratio of CoCrFeNi dual-phase high-entropy alloy are as follows: After holding at 1000℃ for more than 3 hours, further extending the holding time gradually reduces the decrease in yield strength ratio, and the yield strength ratio gradually stabilizes.

[0049] Example 4

[0050] Al is prepared using the short-process preparation method for low yield strength ratio dual-phase high entropy alloys described in this invention. 0.7 The CoCrFeNi dual-phase high-entropy alloy is as follows:

[0051] Al is smelted in a conventional muffle furnace 0.7 The CoCrFeNi dual-phase high-entropy alloy ingot was heated to 1050℃, held for 3 hours, and then water-quenched. The yield strength was 573 MPa, and the tensile strength was 1358 MPa. The strength increased by 21.8%, while the yield strength ratio decreased to 42.2%.

[0052] Figure 4 For the original smelting of Al 0.7 Microstructure and phase content distribution of CoCrFeNi dual-phase high-entropy alloy ingots after heating to 1050℃ for 3 hours and water quenching using the process of this invention. After water quenching at 1050℃ for 3 hours, the alloy microstructure shows an interlayered distribution of FCC and BCC phases. The B2 precipitates are basically dissolved and the feathery structure disappears, with obvious spheroidized B2 phase structure appearing. The FCC and BCC phases account for 63.6% and 36.4%, respectively. Compared with water quenching at 1000℃ for 3 hours, the decrease in yield strength ratio is smaller with a 50℃ increase in heating temperature. The changes in phase content and morphology are related to Al. 0.7 The main reasons for the increased tensile strength, decreased yield strength ratio, and reduced yield strength ratio decrease in CoCrFeNi dual-phase high-entropy alloy.

[0053] Example 5

[0054] Al is prepared using the short-process preparation method for low yield strength ratio dual-phase high entropy alloys described in this invention. 0.7 The CoCrFeNi dual-phase high-entropy alloy is as follows:

[0055] Al will be smelted in a regular muffle furnace. 0.7 The CoCrFeNi dual-phase high-entropy alloy ingot was heated to 1150℃, held for 3 hours, and then water-quenched. The alloy yield strength was 553 MPa, and the tensile strength was 1308 MPa. The strength increased by 17.3%, while the yield strength ratio decreased to 42.3%.

[0056] Figure 5 For the original smelting of Al 0.7 Microstructure and phase content distribution of CoCrFeNi dual-phase high-entropy alloy ingots after heating to 1150℃ for 3 hours and water quenching using the process of this invention. After water quenching at 1150℃ for 3 hours, the alloy microstructure exhibits a layered distribution of FCC and BCC phases, with a significant increase in the thickness of the two phase lamellars. No B2 precipitates are found in the FCC phase, and the spheroidized structure is significantly increased. The FCC and BCC phases account for 66.7% and 33.3%, respectively. Compared to water quenching at 1050℃ for 3 hours, increasing the heating temperature by another 100℃ does not result in a stable yield strength ratio. The alloy phase content, the interlamellar spacing of the two phases, and the content of spheroidized structure are the main reasons for maintaining a stable yield strength ratio.

[0057] Example 6

[0058] Al is prepared using the short-process preparation method for low yield strength ratio dual-phase high entropy alloys described in this invention. 0.7 The CoCrFeNi dual-phase high-entropy alloy is as follows:

[0059] Al will be smelted in a regular muffle furnace. 0.7 The CoCrFeNi dual-phase high-entropy alloy ingot was heated to 1250℃, held for 3 hours, and then water-quenched. The yield strength was 475 MPa, and the tensile strength was 1326 MPa. The strength increased by 18.9%, while the yield-to-tensile ratio decreased to 35.8%.

[0060] Figure 6 For the original smelting of Al 0.7Microstructure and phase content distribution of CoCrFeNi dual-phase high-entropy alloy ingots after heating to 1250℃ for 3 hours and water quenching using the process of this invention. After water quenching at 1250℃ for 3 hours, the alloy microstructure shows an interphase distribution of layered FCC and BCC phases, with a further increase in the lamellar thickness of the two phases. Spheroidized and blocky B2 phase structures are also present in the microstructure, with FCC and BCC phases accounting for 68.7% and 31.3%, respectively. Compared to water quenching at 1150℃ for 3 hours, an increase of 100℃ in heating temperature further reduces the yield strength ratio. The increased alloy phase content, the increased interlamellar spacing between the two phases, and the appearance of spheroidized and blocky B2 phase structures are characteristics of Al... 0.7 The main reason for the further decrease in the yield strength ratio of CoCrFeNi dual-phase high-entropy alloy.

[0061] Example 7

[0062] like Figure 7 As shown, in Examples 2 to 6, Al was obtained by heating at different temperatures and holding for different times within a temperature range of 1000°C to 1250°C and a time range of 1h to 3h. 0.7 True stress-strain curves of a CoCrFeNi dual-phase high-entropy alloy. 0.7 CoCrFeNi dual-phase high-entropy alloy ingots, Al prepared by this invention 0.7 The tensile strength of the CoCrFeNi dual-phase high-entropy alloy increased by 49.6%-91.4%, while the yield strength decreased by 10.0%-36.2%, and the yield ratio decreased by 29.6%-46.3%. This was achieved by rationally controlling the proportions of the FCC and BCC phases, the interlamellar spacing between the two phases, and the size, morphology, and distribution of the B2 precipitate. 0.7 The reduction in yield strength ratio and the increase in tensile strength of CoCrFeNi dual-phase high-entropy alloy can provide effective energy absorption, buffering and shock absorption when subjected to dynamic loads such as impact, vibration and collision, which is of great practical significance for improving the service reliability and safety of dual-phase high-entropy alloy.

Claims

1. A short-process preparation method for a low yield strength ratio dual-phase high-entropy alloy, characterized in that, Includes the following steps: S1. Prepare Al, Co, Cr, Fe, and Ni materials; and weigh each material according to the element types and designed molar ratios of the alloy shown in (1) below. (1) Al x CoCrFeNi, 0.5≤x≤0.9, and the molar ratio of any two elements in the other element content is 1:1; The weighed alloy mixture is then placed into a muffle furnace for melting to obtain a dual-phase high-entropy alloy ingot. S2. Place the dual-phase high-entropy alloy ingot into a resistance furnace and heat it to 600-1300℃ at a heating rate of 2-20℃ / min. S3. When heating to 600-1300℃, stop heating and allow the high-entropy alloy ingot to be held in a resistance furnace at 600-1300℃ for 0.5-36 hours. S4. After the heat treatment is completed, the high-entropy alloy ingot is placed in the quenching medium for quenching to obtain CoCrFeNiAl. x A series of low yield strength ratio dual-phase high entropy alloys.

2. The short-process preparation method for a low yield strength ratio dual-phase high-entropy alloy according to claim 1, characterized in that, The highest temperature inside the resistance furnace during heating is 900-1250℃.

3. The short-process preparation method for a low yield strength ratio dual-phase high-entropy alloy according to claim 1, characterized in that, The heat preservation treatment time is 1 to 3 hours.

4. The short-process preparation method for a low yield strength ratio dual-phase high-entropy alloy according to claim 1, characterized in that, The heating rate of the resistance furnace is 5–10 °C / min.

5. The short-process preparation method for a low yield strength ratio dual-phase high-entropy alloy according to claim 1, characterized in that, The smelting process employs one of the industrially common methods: electric arc melting, induction melting, or suspension melting.

6. The short-process preparation method for a low yield strength ratio dual-phase high-entropy alloy according to claim 1, characterized in that, The resistance furnace is a conventional air resistance furnace or a vacuum resistance furnace.

7. The short-process preparation method for a low yield strength ratio dual-phase high-entropy alloy according to claim 1, characterized in that, The quenching medium is a water-based or oil-based coolant.

8. The short-process preparation method for a low yield strength ratio dual-phase high-entropy alloy according to claim 1, characterized in that, The Al, Co, Cr, Fe, and Ni materials are all in the form of blocks, flakes, or filaments.

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