Method for regulating and controlling grain size of columnar crystal of solidification structure of multi-principal-element molybdenum-niobium-tungsten alloy

Abstract

The invention discloses a method for regulating and controlling the grain size of a columnar crystal of a solidification structure of a multi-principal-element molybdenum-niobium-tungsten alloy, which comprises the following steps of: 1, weighing metal molybdenum, metal niobium, metal tungsten and metal rhenium, mixing, and carrying out vacuum melting to obtain a liquid alloy; and secondly, the liquid alloy obtained in the first step is placed in a crucible to be solidified, and the columnar crystal multi-principal-element molybdenum-niobium-tungsten alloy is obtained. According to the method, the metal rhenium is added into the raw materials to be mixed and then subjected to vacuum melting, the columnar crystal multi-principal-element molybdenum-niobium-tungsten alloy is obtained after solidification, the crystal grain size of the columnar crystal multi-principal-element molybdenum-niobium-tungsten alloy can be regulated and controlled by adding rhenium atoms, the situation that the multi-principal-element molybdenum-niobium-tungsten alloy is in a thick columnar crystal form is avoided, and the mechanical property of the alloy is improved. The method is suitable for grain refinement of the multi-principal-component molybdenum-niobium-tungsten alloy in the technical field of solidification of the multi-principal-component refractory alloy.

Description

Technical Field

[0001] The invention belongs to the technical field of multi-principal-element refractory alloy solidification, and in particular relates to a method for regulating the grain size of columnar crystals in a multi-principal-element molybdenum-niobium-tungsten alloy solidification structure. Background Art

[0002] In the prior art, powder metallurgy is usually used to prepare refractory metal materials, which can obtain fine grain size. However, powder metallurgy alloy materials have high impurity content, low density, and many internal pore defects. Their application performance is significantly limited and cannot meet the requirements of advanced material preparation and service. In view of the shortcomings of powder metallurgy methods, smelting and casting alloys are expected to replace powder metallurgy manufacturing technology in the preparation process of certain refractory alloys due to their low impurity content and dense structure. However, the structure of refractory alloys produced by smelting and casting usually presents a coarse columnar crystal morphology, which will affect the service performance of refractory alloys.

[0003] There is currently no report on the refinement of multi-principal component molybdenum-niobium-tungsten alloy grains in the prior art. Therefore, it is urgently necessary to develop a method that can control the grain size of multi-principal component molybdenum-niobium-tungsten alloy. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the above-mentioned prior art and provide a method for regulating the grain size of columnar crystals in the solidification structure of a multi-principal molybdenum-niobium-tungsten alloy. The method adds metal rhenium to the raw materials and then performs vacuum melting to obtain a columnar crystal multi-principal molybdenum-niobium-tungsten alloy after solidification. The grain size of the columnar crystal multi-principal molybdenum-niobium-tungsten alloy can be regulated, and the problem of coarse size of the multi-principal molybdenum-niobium-tungsten refractory alloy is solved.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a method for regulating the grain size of columnar crystals in the solidification structure of a multi-principal molybdenum-niobium-tungsten alloy, characterized in that the method comprises the following steps:

[0006] Step 1, weighing metal molybdenum, metal niobium, metal tungsten and metal rhenium, mixing them and performing vacuum melting to obtain a liquid alloy;

[0007] Step 2: placing the liquid alloy obtained in step 1 in a crucible for solidification to obtain a columnar crystal multi-principal element molybdenum-niobium-tungsten alloy.

[0008] The above-mentioned method for regulating the grain size of columnar crystals in the solidification structure of a multi-principal element molybdenum-niobium-tungsten alloy is characterized in that the molar ratio of molybdenum atoms, niobium atoms and tungsten atoms in the liquid alloy in step one is 0.95-1.05:0.95-1.05:0.95-1.05, and the molar content of rhenium atoms in the liquid alloy is 2%-10%.

[0009] The present invention adds rhenium atoms with a molar content of 2% to 10% into a liquid alloy to refine the grains of a columnar multi-principal molybdenum-niobium-tungsten alloy. Since the multi-principal molybdenum-niobium-tungsten alloy with a body-centered cubic crystal structure itself has severe lattice distortion, the addition of rhenium elements with a hexagonal crystal structure with screw dislocations can control the growth of crystals during the nucleation and growth of the crystals, resulting in a phenomenon of reducing the grain size. In addition, the doping of rhenium can hinder the diffusion of atoms during the crystal growth process, and also has the effect of inhibiting the growth of grains.

[0010] The above-mentioned method for regulating the grain size of columnar crystals in the solidification structure of a multi-principal element molybdenum-niobium-tungsten alloy is characterized in that the molar content of rhenium atoms in the liquid alloy is 5.5% to 8.5%.

[0011] The present invention can refine the grains of the columnar crystal multi-principal element molybdenum-niobium-tungsten alloy as much as possible by adjusting the molar content of rhenium atoms to 5.5% to 8.5%, and refine the columnar crystal grain size to 160μm to 250μm, so that the columnar crystal multi-principal element molybdenum-niobium-tungsten alloy has excellent strength and plasticity.

[0012] The above-mentioned method for regulating the grain size of columnar crystals in the solidification structure of a multi-principal element molybdenum-niobium-tungsten alloy is characterized in that the mass purity of the metal molybdenum, metal niobium, metal tungsten and metal rhenium in step one is not less than 99.95%.

[0013] The above-mentioned method for regulating the grain size of columnar crystals in the solidification structure of a multi-principal element molybdenum-niobium-tungsten alloy is characterized in that the particle sizes of the metal molybdenum, metal niobium, metal tungsten and metal rhenium in step one are all 2 mm to 8 mm.

[0014] The above-mentioned method for regulating the grain size of columnar crystals in the solidification structure of a multi-principal molybdenum-niobium-tungsten alloy is characterized in that the vacuum melting system in step one is: heating to 2600°C to 2700°C, then heating to 3200°C to 3300°C at a rate of 50°C / min to 100°C / min, and then heating to 3600°C to 3800°C at a rate of 20°C / min to 40°C / min and keeping warm for 4min to 6min.

[0015] The present invention controls the particle size of raw materials to make various metals mix evenly, and then adopts a multi-stage temperature increase vacuum melting process and controls the temperature increase rate during the vacuum melting process, which is conducive to the uniform fusion of various metal elements; by setting the temperature of each stage near the melting point of the metal, it is helpful to improve the quality and uniformity of the liquid alloy; and the first melted metal niobium and metal molybdenum flow in liquid form, and the unmelted tungsten and rhenium are more evenly distributed in the liquid niobium and molybdenum, and the temperature transfer is more sufficient and uniform.

[0016] The above-mentioned method for regulating the grain size of columnar crystals in the solidification structure of a multi-principal element molybdenum-niobium-tungsten alloy is characterized in that the crucible in step 2 is a water-cooled copper crucible.

[0017] The above-mentioned method for regulating the grain size of columnar crystals in the solidification structure of a multi-principal element molybdenum-niobium-tungsten alloy is characterized in that the initial temperature of the water-cooled copper crucible is 5°C to 20°C.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. The present invention can effectively reduce the grain size of columnar multi-principal element molybdenum-niobium-tungsten alloy by adding metal rhenium to the raw materials.

[0020] 2. The present invention can accurately control the grain size of the columnar crystal multi-principal element molybdenum-niobium-tungsten alloy by controlling the content of rhenium atoms in the columnar crystal multi-principal element molybdenum-niobium-tungsten alloy, thereby regulating the performance of the multi-principal element molybdenum-niobium-tungsten alloy; according to different service environments, the multi-principal element molybdenum-niobium-tungsten alloy that is adapted to different service environments can be customized; at the same time, the present invention obtains the optimal rhenium atom dosage for refining the grains of the columnar crystal multi-principal element molybdenum-niobium-tungsten alloy, which helps to control costs.

[0021] 3. The present invention controls the particle size of the raw materials, the multi-stage heating of vacuum melting and the heating rate to achieve uniform fusion of the metal elements; by setting the temperature of each stage near the melting point of the metal, it helps to improve the quality and uniformity of the liquid alloy and reduce defects such as pores inside the columnar crystal multi-principal element molybdenum-niobium-tungsten alloy.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a microstructure diagram of the columnar crystal multi-principal element molybdenum-niobium-tungsten alloy in Example 1 of the present invention.

[0024] Figure 2 This is a microstructure diagram of the columnar crystal multi-principal element molybdenum-niobium-tungsten alloy in Comparative Example 1 of the present invention.

[0025] Figure 3 This is a microstructure diagram of the dendrite multi-principal element molybdenum-niobium-tungsten alloy in Comparative Example 2 of the present invention.

[0026] Figure 4 This is a microstructure diagram of the dendrite multi-principal element molybdenum-niobium-tungsten alloy in Comparative Example 3 of the present invention.

[0027] Figure 5 This is a microstructure diagram of the columnar crystal multi-principal element molybdenum-niobium-tungsten alloy in Example 2 of the present invention.

[0028] Figure 6This is a microstructure diagram of the columnar crystal multi-principal element molybdenum-niobium-tungsten alloy in Example 3 of the present invention.

[0029] Figure 7 This is a microstructure diagram of the columnar crystal multi-principal element molybdenum-niobium-tungsten alloy in Example 4 of the present invention.

[0030] Figure 8 This is a microstructure diagram of the columnar crystal multi-principal element molybdenum-niobium-tungsten alloy in Example 5 of the present invention. DETAILED DESCRIPTION

[0031] Example 1

[0032] The method of this embodiment includes the following steps:

[0033] Step 1, weighing metal molybdenum, metal niobium, metal tungsten and metal rhenium with a particle size of 2mm to 8mm, mixing and vacuum melting to obtain a liquid alloy; the mass purity of the metal molybdenum, metal niobium, metal tungsten and metal rhenium is not less than 99.95%, the molar ratio of molybdenum atoms, niobium atoms and tungsten atoms in the liquid alloy is 1:1:1, and the molar content of rhenium atoms in the liquid alloy is 6%; the vacuum melting system is: heating to 2700°C, then heating to 3250°C at a rate of 70°C / min, and then heating to 3700°C at a rate of 30°C / min and keeping warm for 5 minutes;

[0034] Step 2: solidify the liquid alloy obtained in step 1 in a water-cooled copper crucible with an initial temperature of 10° C. to obtain a columnar multi-principal element molybdenum-niobium-tungsten alloy.

[0035] The columnar multi-principal element molybdenum-niobium-tungsten alloy obtained in this embodiment is subjected to microstructural analysis. Figure 1 As shown, the grain morphology of the columnar multi-principal element molybdenum-niobium-tungsten alloy is blocky, and the average grain size is 177 μm.

[0036] Comparative Example 1

[0037] The difference between this comparative example and Example 1 is that in step 1, the molar ratio of molybdenum, niobium and tungsten atoms in the liquid alloy is 1:1:1, and the molar content of rhenium atoms in the liquid alloy is 0%.

[0038] The microstructure of the multi-principal element molybdenum-niobium-tungsten alloy obtained in this comparative example is analyzed. Figure 2 As shown, the grain morphology of the multi-principal element molybdenum-niobium-tungsten alloy is columnar, and the average grain size is 1285 μm; compared with the columnar crystal multi-principal element molybdenum-niobium-tungsten alloy of Example 1, the grains of the multi-principal element molybdenum-niobium-tungsten alloy in this comparative example are larger, indicating that the addition of rhenium element can effectively reduce the grain size of the columnar crystal multi-principal element molybdenum-niobium-tungsten alloy.

[0039] Comparative Example 2

[0040] The difference between this comparative example and Example 1 is that the initial temperature of the graphite clay crucible in step 2 is 25°C.

[0041] The microstructure of the multi-principal element molybdenum-niobium-tungsten alloy obtained in this comparative example is analyzed. Figure 3 As shown, the grain morphology of the multi-principal element molybdenum-niobium-tungsten alloy is dendrite.

[0042] Comparative Example 3

[0043] The difference between this comparative example and comparative example 2 is that in step 1, the molar ratio of molybdenum, niobium and tungsten atoms in the liquid alloy is 1:1:1, and the molar content of rhenium atoms in the liquid alloy is 0%.

[0044] The microstructure of the multi-principal element molybdenum-niobium-tungsten alloy obtained in this comparative example is analyzed. Figure 4 As shown, the grain morphology of the multi-principal molybdenum-niobium-tungsten alloy is dendrite, and the grain size of the multi-principal molybdenum-niobium-tungsten alloy in this comparative example is not significantly different from that in comparative example 2, indicating that rhenium atoms have no regulating effect on the grain size of the dendrite multi-principal molybdenum-niobium-tungsten alloy.

[0045] Example 2

[0046] The difference between this embodiment and embodiment 1 is that in step 1, the molar ratio of molybdenum, niobium and tungsten atoms in the liquid alloy is 1:1:1, and the molar content of rhenium atoms in the liquid alloy is 2%.

[0047] The columnar multi-principal element molybdenum-niobium-tungsten alloy obtained in this embodiment is subjected to microstructural analysis. Figure 5 As shown, the grain morphology of the columnar multi-principal element molybdenum-niobium-tungsten alloy is columnar, and the average grain size is 818 μm.

[0048] Example 3

[0049] The difference between this embodiment and embodiment 1 is that in step 1, the molar ratio of molybdenum, niobium and tungsten atoms in the liquid alloy is 1:1:1, and the molar content of rhenium atoms in the liquid alloy is 4%.

[0050] The columnar multi-principal element molybdenum-niobium-tungsten alloy obtained in this embodiment is subjected to microstructural analysis. Figure 6 As shown, the grain morphology of the columnar multi-principal element molybdenum-niobium-tungsten alloy is ellipsoidal, and the average grain size is 445 μm.

[0051] Example 4

[0052] The difference between this embodiment and embodiment 1 is that in step 1, the molar ratio of molybdenum, niobium and tungsten atoms in the liquid alloy is 1:1:1, and the molar content of rhenium atoms in the liquid alloy is 8%.

[0053] The columnar multi-principal element molybdenum-niobium-tungsten alloy obtained in this embodiment is subjected to microstructural analysis. Figure 7 As shown, the grain morphology of the columnar multi-principal element molybdenum-niobium-tungsten alloy is blocky, and the average grain size is 223 μm.

[0054] Example 5

[0055] The difference between this embodiment and embodiment 1 is that in step 1, the molar ratio of molybdenum, niobium and tungsten atoms in the liquid alloy is 1:1:1, and the molar content of rhenium atoms in the liquid alloy is 10%.

[0056] The columnar multi-principal element molybdenum-niobium-tungsten alloy obtained in this embodiment is subjected to microstructural analysis. Figure 8 As shown, the grain morphology of the columnar multi-principal molybdenum-niobium-tungsten alloy is blocky and columnar, and the average grain size is 364 μm.

[0057] Example 6

[0058] The method of this embodiment includes the following steps:

[0059] Step 1, weighing metal molybdenum, metal niobium, metal tungsten and metal rhenium with a particle size of 2mm to 8mm, mixing and vacuum melting to obtain a liquid alloy; the mass purity of the metal molybdenum, metal niobium, metal tungsten and metal rhenium is not less than 99.95%, the molar ratio of molybdenum atoms, niobium atoms and tungsten atoms in the liquid alloy is 0.95:1:1.05, and the molar content of rhenium atoms in the liquid alloy is 5.5%; the vacuum melting system is: heating to 2600°C, then heating to 3200°C at a rate of 50°C / min, and then heating to 3600°C at a rate of 20°C / min and keeping warm for 4 minutes;

[0060] Step 2: solidify the liquid alloy obtained in step 1 in a water-cooled copper crucible with an initial temperature of 5° C. to obtain a columnar multi-principal element molybdenum-niobium-tungsten alloy.

[0061] After inspection, it was found that the grain morphology of the columnar multi-principal element molybdenum-niobium-tungsten alloy obtained in this embodiment was blocky, and the average grain size was 236 μm.

[0062] Example 7

[0063] The method of this embodiment includes the following steps:

[0064] Step 1, weighing metal molybdenum, metal niobium, metal tungsten and metal rhenium with a particle size of 2mm to 8mm, mixing and vacuum melting to obtain a liquid alloy; the mass purity of the metal molybdenum, metal niobium, metal tungsten and metal rhenium is not less than 99.95%, the molar ratio of molybdenum atoms, niobium atoms and tungsten atoms in the liquid alloy is 1.05:0.95:1, and the molar content of rhenium atoms in the liquid alloy is 8.5%; the vacuum melting system is: heating to 2700°C, then heating to 3300°C at a rate of 100°C / min, and then heating to 3800°C at a rate of 40°C / min and keeping warm for 6 minutes;

[0065] Step 2: solidify the liquid alloy obtained in step 1 in a water-cooled copper crucible with an initial temperature of 15° C. to obtain a columnar multi-principal element molybdenum-niobium-tungsten alloy.

[0066] After inspection, it was found that the grain morphology of the columnar multi-principal element molybdenum-niobium-tungsten alloy obtained in this embodiment was blocky, and the average grain size was 247 μm.

[0067] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for regulating the grain size of columnar crystals in a multi-principal molybdenum-niobium-tungsten alloy solidification structure, characterized in that: The method comprises the following steps: Step 1, weighing metal molybdenum, metal niobium, metal tungsten and metal rhenium, mixing them and performing vacuum melting to obtain a liquid alloy; Step 2: placing the liquid alloy obtained in step 1 in a crucible for solidification to obtain a columnar crystal multi-principal element molybdenum-niobium-tungsten alloy.

2. The method for regulating the grain size of columnar crystals in the solidification structure of a multi-principal molybdenum-niobium-tungsten alloy according to claim 1, characterized in that: In step 1, the molar ratio of molybdenum atoms, niobium atoms and tungsten atoms in the liquid alloy is 0.95-1.05:0.95-1.05:0.95-1.05, and the molar content of rhenium atoms in the liquid alloy is 2%-10%.

3. The method for regulating the grain size of columnar crystals in the solidification structure of a multi-principal molybdenum-niobium-tungsten alloy according to claim 2, characterized in that: The molar content of rhenium atoms in the liquid alloy is 5.5% to 8.5%.

4. The method for regulating the grain size of columnar crystals in the solidification structure of a multi-principal molybdenum-niobium-tungsten alloy according to claim 1, characterized in that: The mass purity of the metal molybdenum, metal niobium, metal tungsten and metal rhenium in step 1 is not less than 99.95%.

5. The method for regulating the grain size of columnar crystals in the solidification structure of multi-principal molybdenum-niobium-tungsten alloy according to claim 1, characterized in that: The particle sizes of the metal molybdenum, metal niobium, metal tungsten and metal rhenium in step 1 are all 2 mm to 8 mm.

6. The method for regulating the grain size of columnar crystals in the solidification structure of a multi-principal molybdenum-niobium-tungsten alloy according to claim 1, characterized in that: The vacuum melting system in step 1 is: heating to 2600°C-2700°C, then heating to 3200°C-3300°C at a rate of 50°C / min-100°C / min, and then heating to 3600°C-3800°C at a rate of 20°C / min-40°C / min and keeping warm for 4min-6min.

7. The method for regulating the grain size of columnar crystals in the solidification structure of a multi-principal molybdenum-niobium-tungsten alloy according to claim 1, characterized in that: The crucible in step 2 is a water-cooled copper crucible.

8. The method for regulating the grain size of columnar crystals in the solidification structure of a multi-principal element molybdenum-niobium-tungsten alloy according to claim 7, characterized in that: The initial temperature of the water-cooled copper crucible is 5°C to 20°C.

Images