CN111822806A - A method for vacuum brazing Al0.3CoCrFeNi high-entropy alloy with NiZr brazing filler metal - Google Patents

Abstract

The invention discloses a method for vacuum brazing Al _{0.3 CoCrFeNi} high-entropy alloy with NiZr brazing filler metal, which belongs to the field of welding technology. The parts to be welded are ground and pretreated to obtain the brazing base metal. The foil _brazing filler metal and the base metal are washed with acetone and ethanol and dried in turn. , Al _0.3 CoCrFeNi high-entropy alloys are placed in sequence to obtain components to be welded, and a graphite compact of 1.5kPa is placed above the components to be welded, and brazing is performed in an environment with a vacuum degree of ‑5.0×10 ^‑3 Pa or less. The brazing material used in the invention is simple, economical and applicable, and the average shear strength of the obtained Al _0.3 CoCrFeNi high-entropy alloy and tungsten joint is not less than 215 MPa, which has good promotion value.

Description

A method for vacuum brazing Al0.3CoCrFeNi high-entropy alloy with NiZr brazing filler metal

technical field

The invention relates to a brazing filler metal vacuum brazing method, in particular to a NiZr brazing filler metal vacuum brazing method for an Al _0.3 CoCrFeNi high-entropy alloy, belonging to the technical field of welding.

Background technique

Entropy was proposed by the German physicist Clausius in 1865, and high-entropy alloys were not prepared until 2004 and were put into use in 2010. A high-entropy alloy refers to an alloy formed of five or more metals in equal (equimolar ratio) or approximately equal amounts. With the development of technology, the second generation of high-entropy alloys and high-entropy ceramics have also appeared. The constituent elements of the second-generation high-entropy alloys can be in non-equimolar ratios, and the constituent elements are four or more.

The main components of traditional alloys are usually only one or two metals, and the main components are used as the matrix and trace amounts of other trace elements are added to improve the performance of the alloy. As mentioned above, there are many main components in high-entropy alloys, and the molar ratios are roughly equal. According to the traditional concept, if the more kinds of metals are added to the alloy, the more brittle the alloy is. However, high-entropy alloys are different from traditional alloys. , high-entropy alloys do not become brittle due to roughly equal solid solution of various metals.

Typically, Chinese patent document CN108149117A discloses a MoCrFeMnNi high-entropy alloy and a preparation method thereof. The high-entropy alloy adopts an equimolar ratio of components. Press to make a round cake, then put the round cake into the reaction kettle, and place an igniter on the round cake to consume oxygen, and finally prepare the final brittle MoCrFeMnNi high-entropy alloy through aluminothermic reaction, here In the process, it is relatively difficult to achieve oxygen consumption through the igniter. When the oxygen concentration is relatively low, it cannot be further consumed, but under high temperature conditions, the residual oxygen is still easy to combine with the metal elements in the alloy. In addition, the preparation process is relatively simple, mainly after mixing uniformly and then pressing and molding, and the bonding performance between metal element particles is relatively poor.

The Al _0.3 CoCrFeNi high-entropy alloy has a face-centered cubic crystal structure with good strength and toughness. According to reports, its irradiation performance is significantly better than that of traditional nuclear energy structural materials such as M316 stainless steel, zirconium alloy, and nickel-based alloy, and is used in nuclear energy aerospace and other fields.

Al _0.3 CoCrFeNi high-entropy alloys are radiation-resistant high-temperature nuclear energy structural materials and can be used in hot-end components in aerospace, nuclear energy and other fields. Therefore, the connection joints should have good radiation resistance and high temperature resistance. and cost, it is difficult to realize the fabrication of complex Al _0.3 CoCrFeNi high-entropy alloy parts, therefore, the realization of the connection of Al _0.3 CoCrFeNi high-entropy alloy has important application value. Since the Al _0.3 CoCrFeNi high-entropy alloy has five components, complex physical and chemical reactions occur in the welded joints under high temperature conditions such as ordinary fusion welding, such as MIG welding, laser welding, and electron beam welding, and complex intermetallic compounds are easily formed. joint strength. At the same time, the Al _0.3 CoCrFeNi high-entropy alloy has poor thermal conductivity, and fusion welding under high temperature conditions is prone to thermal cracks.

SUMMARY OF THE INVENTION

In view of this, the present invention provides a method for vacuum brazing Al _0.3 CoCrFeNi high-entropy alloy with NiZr brazing material, and realizes the connection of Al _0.3 CoCrFeNi high-entropy alloy by brazing with a lower connection temperature.

In order to achieve the above object, the present invention adopts the following technical solutions:

A method for vacuum brazing Al _0.3 CoCrFeNi high-entropy alloy with NiZr brazing filler metal, the steps are as follows:

1) Weigh Ni foil and Zr foil whose mass percentage sum is 100%, stack them together in the order of Ni foil, Zr foil, and Ni foil, and cold-press to form a thin brazing filler metal;

2) Grinding and preprocessing the parts to be welded of the Al _0.3 CoCrFeNi high-entropy alloy to obtain a brazing base metal;

3) Immerse the foil brazing filler metal and the base metal in acetone, dry after ultrasonic cleaning for 10-30 minutes, and then put them in ethanol solution for ultrasonic cleaning for 10-20 minutes and then dry;

4) Place the dried foil brazing filler metal and the base metal to be welded in the order of Al _0.3 CoCrFeNi high-entropy alloy, foil brazing filler metal, and Al _0.3 CoCrFeNi high-entropy alloy from bottom to top to obtain the component to be welded, and then Place a 1.5kPa graphite block above the components to be welded to prevent relative movement of the components during the welding process;

5) Brazing the components to be welded and the graphite compact in an environment where the vacuum degree is below -5.0×10 ^-3 Pa.

Further, the purity of the Ni foil and the Zr foil in step 1) is not less than 99.5%;

The pressure of cold pressing is not less than 20MPa.

Further, the thickness of the Ni foil is 20 μm, and the thickness of the Zr foil is 50 μm.

Further, the grinding operation described in step 2) is to grind the parts to be welded with 400-mesh, 800-mesh, 1200-mesh, and 2000-mesh sandpaper in sequence.

Further, the Al _0.3 CoCrFeNi high-entropy alloy is made of Al, Co, Cr, Fe, and Ni metals in an atomic percentage of 0.3:1:1:1:1, and is produced by vacuum suspension smelting.

Further, the operation of the brazing described in step 5) is to be heated to 900°C with a heating rate of 20°C/min, continue to be heated to 1050°C with a heating rate of 10°C/min, be incubated for 10min, and then be heated to 5°C/min. The temperature is raised to 1140℃-1200℃ at the rate of 1140℃, and then brazing is carried out.

Further, the temperature of brazing is 1060°C, 1180°C or 1200°C.

Further, the brazing temperature was 1160° C., and the holding time was 30 minutes.

The invention adopts metal Ni and metal Zr to braze the Al _0.3 CoCrFeNi high-entropy alloy, the Ni and Zr metals have good radiation resistance, Ni does not react with the Al _0.3 CoCrFeNi high-entropy alloy component, avoids the formation of a brittle and hard phase, and at the same time , the eutectic reaction between Ni foil and zirconium foil can reduce the brazing connection temperature.

The brazing material used in the invention is simple, economical and applicable, and the average shear strength of the obtained Al _0.3 CoCrFeNi high-entropy alloy and tungsten joint is not less than 215 MPa, which has good promotion value.

Description of drawings

Fig. 1 is the variation diagram of brazing temperature in Embodiment 1 of the present invention;

FIG. 2 is a layout diagram of components to be welded in Embodiment 1 of the present invention;

FIG. 3 is a backscattering picture of the brazed joint in Example 1 of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In the embodiment, the purity of Ni foil and Zr foil is 99.7%; the thickness of Ni foil is 20 μm, and the thickness of Zr foil is 50 μm; Al _0.3 CoCrFeNi high-entropy alloy is Al, Co, Cr, Fe, Ni metal by atom. The percentage of 0.3:1:1:1:1 is made by vacuum suspension smelting after batching; the change diagram of brazing temperature is shown in Figure 1.

Example 1

The method of vacuum brazing Al _0.3 CoCrFeNi high-entropy alloy with NiZr filler metal, the steps are as follows:

1) Weigh Ni foil and Zr foil with a mass percentage of 53:47, stack them together in the order of Ni foil, Zr foil and Ni foil, put them on a cold press and cold-press them to make thin brazing filler metals. The applied pressure is 40MPa. The pressed sheet brazing filler metal was ultrasonically cleaned in alcohol and acetone for 10 min respectively;

2) grinding and preprocessing the parts to be welded of the Al _0.3 CoCrFeNi high-entropy alloy with 400-mesh, 800-mesh, 1200-mesh, and 2000-mesh sandpaper in turn to obtain a brazing base material;

3) Immerse the foil brazing filler metal and base metal in acetone, ultrasonically clean for 20 minutes and then dry, and then put them in an ethanol solution for ultrasonic cleaning for 10 minutes and then dry;

4) Place the dried foil brazing filler metal and the base metal to be welded in the order of Al _0.3 CoCrFeNi high-entropy alloy, foil brazing filler metal, and Al _0.3 CoCrFeNi high-entropy alloy from bottom to top to obtain the component to be welded, and then A 1.5kPa graphite block is placed above the components to be welded, and the layout is shown in Figure 2;

5) When the vacuum degree of the components to be welded and the graphite compact is below -5.0×10 ^-3 Pa, start heating and heating, and the heating rate is 20℃/min. When the temperature reaches 900℃, change the heating rate to 10℃. Heating to 1050°C, holding for 10 minutes, then heating to a brazing temperature of 1140°C-1200°C at a rate of 5°C/min, brazing at 1160°C, holding for 30 minutes, and then cooling at a rate of 5°C/min, After cooling to room temperature, the sample was taken out, and the backscattered image results are shown in Figure 3.

Example 2

The method of vacuum brazing Al _0.3 CoCrFeNi high-entropy alloy with NiZr filler metal, the steps are as follows:

1) Weigh Ni foil and Zr foil with a mass percentage of 1:1, stack them together in the order of Ni foil, Zr foil, and Ni foil, put them on a cold press to make thin brazing filler metals, and the applied pressure is 70MPa. The pressed sheet brazing filler metal was ultrasonically cleaned in alcohol and acetone for 10 min respectively;

2) grinding and preprocessing the parts to be welded of the Al _0.3 CoCrFeNi high-entropy alloy with 400-mesh, 800-mesh, 1200-mesh, and 2000-mesh sandpaper in turn to obtain a brazing base material;

3) Immerse the foil brazing filler metal and base metal in acetone, ultrasonically clean for 10 minutes and then dry, and then put them in an ethanol solution for ultrasonic cleaning for 30 minutes and then dry;

4) Place the dried foil brazing filler metal and the base metal to be welded in the order of Al _0.3 CoCrFeNi high-entropy alloy, foil brazing filler metal, and Al _0.3 CoCrFeNi high-entropy alloy from bottom to top to obtain the component to be welded, and then Place a 1.5kPa graphite compact above the components to be welded;

5) When the vacuum degree of the components to be welded and the graphite compact is below -5.0×10 ^-3 Pa, start heating and heating, and the heating rate is 20℃/min. When the temperature reaches 900℃, change the heating rate to 10℃. Heating to 1050°C, holding for 10 minutes, then heating to a brazing temperature of 1140°C-1200°C at a rate of 5°C/min, brazing at 1180°C, holding for 30 minutes, and then cooling at a rate of 5°C/min, After cooling to room temperature, take out the sample.

Example 2

The method of vacuum brazing Al _0.3 CoCrFeNi high-entropy alloy with NiZr filler metal, the steps are as follows:

1) Weigh Ni foil and Zr foil with a mass percentage of 49:51, stack them together in the order of Ni foil, Zr foil, and Ni foil, put them on a cold press to make thin brazing filler metals, and apply a pressure of 120MPa. The pressed sheet brazing filler metal was ultrasonically cleaned in alcohol and acetone for 10 min respectively;

2) grinding and preprocessing the parts to be welded of the Al _0.3 CoCrFeNi high-entropy alloy with 400-mesh, 800-mesh, 1200-mesh, and 2000-mesh sandpaper in turn to obtain a brazing base material;

3) Immerse the foil brazing filler metal and base metal in acetone, ultrasonically clean for 10 minutes and then dry, and then put them in an ethanol solution for ultrasonic cleaning for 30 minutes and then dry;

4) Place the dried foil brazing filler metal and the base metal to be welded in the order of Al _0.3 CoCrFeNi high-entropy alloy, foil brazing filler metal, and Al _0.3 CoCrFeNi high-entropy alloy from bottom to top to obtain the component to be welded, and then Place a 1.5kPa graphite compact above the components to be welded;

5) When the vacuum degree of the components to be welded and the graphite compact is below -5.0×10 ^-3 Pa, start heating and heating, and the heating rate is 20℃/min. When the temperature reaches 900℃, change the heating rate to 10℃. Heating to 1050°C, holding for 10 minutes, then heating to a brazing temperature of 1140°C-1200°C at a rate of 5°C/min, brazing at 1200°C, holding for 30 minutes, and then cooling at a rate of 5°C/min, After cooling to room temperature, take out the sample.

Claims (9)

1. NiZr brazing filler metal vacuum brazing Al_0.3The method for the CoCrFeNi high-entropy alloy is characterized by comprising the following steps of:

1) weighing Ni foil and Zr foil with the sum of the mass percent of 100%, overlapping the Ni foil, the Zr foil and the Ni foil in sequence, and cold-pressing to form a sheet solder;

2) for Al_0.3Polishing the part to be welded of the CoCrFeNi high-entropy alloy to obtain a brazing base metal;

3) immersing the foil brazing filler metal and the base material into acetone, ultrasonically cleaning for 10-30min, drying, then placing into an ethanol solution, ultrasonically cleaning for 10-20min, and drying;

4) sequentially using Al to the dried foil brazing filler metal and to-be-welded parent metal from bottom to top_0.3CoCrFeNi high-entropy alloy, foil brazing filler metal and Al_0.3Sequentially placing CoCrFeNi high-entropy alloy to obtain a component to be welded, and placing a graphite pressing block of 1.5kPa above the component to be welded;

5) the components to be welded and the graphite pressing block are pressed in a vacuum degree of-5.0 multiplied by 10^-3Brazing is performed in an atmosphere of Pa or less.

2. NiZr brazing filler metal vacuum brazing Al according to claim 1_0.3The method for preparing the CoCrFeNi high-entropy alloy is characterized in that the purity of the Ni foil and the Zr foil in the step 1) is not lower than 99.5%.

3. NiZr brazing filler metal vacuum brazing Al according to claim 1_0.3The method for preparing the CoCrFeNi high-entropy alloy is characterized in that the pressure of cold pressing in the step 1) is not less than 20 MPa.

4. A method of NiZr solder vacuum brazing al0.3cocrfeni high entropy alloy according to any of the claims 1-3, characterized in that the Ni foil thickness is 20 μ ι η and the Zr foil thickness is 50 μ ι η.

5. NiZr brazing filler metal vacuum brazing Al according to claim 1_0.3The method for preparing the CoCrFeNi high-entropy alloy is characterized in that the grinding operation in the step 2) is to sequentially grind the parts to be welded with 400 meshesAnd sanding with 800 meshes of sand paper, 1200 meshes of sand paper and 2000 meshes of sand paper.

6. NiZr brazing filler metal vacuum brazing Al according to claim 1_0.3The method for preparing the CoCrFeNi high-entropy alloy is characterized in that Al is obtained in the step 2)_0.3The CoCrFeNi high-entropy alloy is Al, Co, Cr, Fe and Ni metal, and the alloy comprises the following components in percentage by atom of 0.3: 1: 1: 1:1, preparing the raw materials, and then carrying out vacuum suspension smelting to prepare the finished product.

7. NiZr brazing filler metal vacuum brazing Al according to claim 1_0.3The method for the CoCrFeNi high-entropy alloy is characterized in that the brazing operation in the step 5) comprises the steps of raising the temperature to 900 ℃ at a heating rate of 20 ℃/min, then continuing raising the temperature to 1050 ℃ at a heating rate of 10 ℃/min, keeping the temperature for 10min, raising the temperature to 1140-1200 ℃ at a heating rate of 5 ℃/min, then brazing, keeping the temperature for no more than 40min, and then cooling to room temperature at a speed of 5 ℃/min.

8. NiZr brazing filler metal vacuum brazing Al according to claim 7_0.3The method for preparing the CoCrFeNi high-entropy alloy is characterized in that the brazing temperature is 1060 ℃, 1180 ℃ or 1200 ℃.

9. NiZr brazing filler metal vacuum brazing Al according to claim 7_0.3The method for preparing the CoCrFeNi high-entropy alloy is characterized in that the brazing temperature is 1160 ℃ and the heat preservation time is 30 min.

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