CN107841672A - High density ReWTaMoNb containing RexHigh entropy alloy material and preparation method - Google Patents

Abstract

The invention discloses a high-density ReWTaMoNb _X high-entropy alloy material containing Re and a preparation method thereof. The composition of the alloy material is ReWTaMoNb _X , and the molar ratio of any two elements among Re/W/Ta/Mo elements in the alloy is 0.95 ~1.05, molar ratio x=0~1 of Nb to any other element. The preparation method is as follows: mixing: weighing Re, W-Mo, Ta, Nb metal powders, ball milling and mixing evenly; preparing prefabricated blocks: using cold high pressure forming technology to make the mixed powders prepared in step 1 into prefabricated blocks; electric arc Melting and preparing high-entropy alloys: using a high-vacuum non-consumable arc melting furnace under the protection of high-purity argon to melt the prefabricated blocks into master alloy ingots. The obtained high-entropy alloy material has high density and high hardness, the density is not lower than 15g/cm ³ , the hardness is not lower than 5700MPa, and can be used in the fields of nuclear industry, aerospace and high-pressure physics.

Description

Re-containing high-density ReWTaMoNbX high-entropy alloy material and preparation method

technical field

The invention relates to a Re-containing high-density ReWTaMoNb _X high-entropy alloy material and a preparation method thereof, belonging to the technical field of alloy materials.

Background technique

Due to the high mixing entropy of high-entropy alloys, which is higher than the melting entropy of alloys, the alloys will not form a large number of intermetallic compounds after solidification, but will form simple solid solution phases such as body-centered cubic or face-centered cubic. At the same time, high-entropy alloys have severe lattice distortions leading to high solid solution strengthening and hysteretic diffusion of atoms, so they have a series of excellent properties, including high hardness, high work hardening, high temperature softening resistance, corrosion resistance, and high electrical resistivity. The combination of high-entropy alloys makes the application level of high-entropy alloys colorful, and the potential application prospects are very broad, which has become one of the current research hotspots.

In the cutting-edge science and technology, the navigation instrument gyroscope in the aerospace field, the balance counterweight of the rotating blade of the helicopter, etc.; the drug type cover in the weapon industry, the shielding material of the nuclear reactor, etc.; Materials with higher densities are desired.

So far, the most studied high-entropy alloy elements are Al, Co, Cr, Cu, Fe, Mn, Ni, Ti, and V. Almost all reports on the mechanical properties of high-entropy alloys at room temperature are added to the CoCrFeNi matrix. or several elements. Another widely studied high-entropy alloy element is Cr, Hf, Mo, Nb, Ta, Ti, V, W, and Zr. Most of these elements are refractory elements. Such refractory alloys are usually HfNbTaZr, MoNbTaW, CrMoNbTa and CrNbVZr is the base. However, the densities of the high-entropy alloys developed so far are all low, among which WNbMoTa has the highest density, only 13.75 g/cm ³ . At the same time, there are few reports on high-entropy alloy systems with high density Re.

Contents of the invention

In view of the low density of existing high-entropy alloys, the present invention, based on the design concept of high-entropy alloys, rationally selects high-density metal elements that meet the conditions for solid solution formation, and successfully prepares a high-density ReWTaMoNb _X high-entropy alloy material containing Re.

The invention also provides a preparation method of high-density ReWTaMoNb _X high-entropy alloy material. In the method, fine powder raw materials are used to achieve uniform powder mixing, and cold high-pressure forming technology is used to effectively reduce the air content in the prefabricated block.

In order to solve the above-mentioned technical problems, the present invention provides a high-density ReWTaMoNb _X high-entropy alloy material containing Re, which is characterized in that: the composition of the alloy material is ReWTaMoNb _X , and any two of Re/W/Ta/Mo elements in the alloy The molar ratio of the elements is 0.95-1.05, and the molar ratio x=0-1 between Nb and any other element.

As the preference of the above technical solution, the Re-containing high-density ReWTaMoNb _X high-entropy alloy material provided by the present invention further includes part or all of the following technical features:

As an improvement of the above technical solution, the obtained high-entropy alloy material has high density and high hardness, the density is not lower than 15g/cm ³ , and the hardness is not lower than 5700MPa.

A method for preparing a Re-containing high-density ReWTaMoNb _X high-entropy alloy material, characterized in that it comprises the following steps:

Step 1. Mixing: Weigh Re, W-Mo, Ta, Nb metal powders according to the molar ratio of 0.95-1.05: 1.9-2.1: 0.95-1.05: 0-1, and mix them evenly by ball milling; the W-Mo metal powders It is a mixed powder of W powder and Mo powder with a molar ratio of 0.95-1.05:0.95-1.05, or a W-Mo alloy powder with a molar ratio of W and Mo of 0.95-1.05:0.95-1.05;

Step 2, preparing prefabricated blocks: using cold high pressure forming technology to make the mixed powder prepared in step 1 into prefabricated blocks;

Step 3, preparing high-entropy alloy by arc melting: using a high-vacuum non-consumable arc melting furnace to melt the prefabricated block into a master alloy ingot under the protection of high-purity argon.

As the preference of the above-mentioned technical scheme, the preparation method of the Re-containing high-density ReWTaMoNb _X high-entropy alloy material provided by the present invention further includes part or all of the following technical features:

As an improvement of the above technical solution, the purity of the Re, W-Mo, Ta, Nb metal powders are all greater than 99.9%, and the particle size distribution of the powders is 2-20 μm. The mixing process adopts a light ball mill, a polyethylene ball mill jar, and zirconia balls, and the ball milling time is 20-30 hours.

As an improvement of the above technical solution, in the second step, the pressing pressure is 300-400 MPa, and the holding time is 5-10 min.

As an improvement of the above technical solution, in the second step, the mold used for pressing is a WC cemented carbide mold.

As an improvement of the above technical solution, in the third step, the Ar atmosphere is introduced into the melting furnace so that the pressure relative to the standard atmospheric pressure reaches -0.01MPa, and the melting process parameters are: the output power is 45% to 50%, and the current is 225 ～250A, the front and back sides are smelted repeatedly 2-3 times, each smelting time is 2-3min.

The ReWTaMoNb _X high-entropy alloy material prepared by the invention has high density and high hardness, the density is not lower than 15g/cm ³ , and the hardness is not lower than 5700MPa, and can be used in the fields of nuclear industry, aerospace and high pressure physics.

There are many elements in high-entropy alloys, and the interactions between elements are different, which may form some other phases. Therefore, how to judge and predict the phase composition of high-entropy alloys is very important. Atomic radius difference (δ), mixing enthalpy (ΔH _mix ) and mixing entropy (ΔS _mix ) play a dominant role in determining the formation of high-entropy alloy solid solution phases, and the formation range of solid solution phases is: 0≤δ≤8.5; -22≤ΔH _mix ≤7kJ/mol; 11≤ΔS _mix ≤19.5J/(K·mol). In order to simplify the prediction criteria, the parameters And it is concluded that the formation region of high entropy alloy solid solution is Ω≥1.1 and δ≤6.6. When designing the alloy composition, this parameter can effectively predict whether the alloy will form a solid solution structure

Compared with the prior art, the technical solution of the present invention has the following beneficial effects: 1. According to the existing high-entropy alloy design concept, the present invention rationally selects relatively high-density metal elements, and successfully prepares a high-density high-entropy alloy containing Re The alloy material ReWTaMoNb _X has further improved the high-entropy alloy system; the microstructure of the alloy consists of BCC solid solution phase (content higher than 95%), and a small amount of diffusely distributed Ta/Nb-rich particle phase and Re-rich nanophase. Composition of ordered solid solutions.

2. The ReWTaMoNb _X high-entropy alloy material prepared by the present invention has high density, which is between 15.02-16.77g/cm ³ , which is higher than the existing high-entropy alloy material; it has relatively high hardness, and its hardness is 5754MPa-6402MPa.

3. The raw materials used in the preparation process of the present invention are all fine powders, which can effectively improve the uniformity of the alloy, reduce the number and length of high-temperature melting of refractory metals, and improve the melting efficiency; the cold high-pressure forming technology can effectively reduce the air content in the prefabricated block , to avoid the influence of interstitial elements (N, O, H) on its properties during the smelting process, so as to obtain qualified alloy ingots.

The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the description, and in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable , below in conjunction with the preferred embodiment, the detailed description is as follows.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings of the embodiments will be briefly introduced below.

Fig. 1 is the process flow chart of the present invention to prepare high-density ReWTaMoNb _X high-entropy alloy material;

Figure 2 is the XRD patterns of ReWTaMoNb _X high-entropy alloys with different Nb contents;

Wherein: Fig. 2 (curve a) is the XRD pattern of the ReWTaMo high-entropy alloy prepared in Example 1; Fig. 2 (curve b) is the XRD pattern of the ReWTaMoNb _0.2 high-entropy alloy prepared in Example 2; Fig. 2 (curve c ) is the XRD pattern of the ReWTaMoNb _0.5 high-entropy alloy prepared in Example 3; Fig. 2 (curve d) is the XRD pattern of the ReWTaMoNb _0.8 high-entropy alloy prepared in Example 4; Fig. 2 (curve e) is prepared in Example 5 XRD pattern of the obtained ReWTaMoNb high-entropy alloy;

Figure 3 is an optical microstructure diagram of ReWTaMoNb _X high-entropy alloys with different Nb contents;

Wherein: Fig. 3 (a) is the optical microstructure diagram of the ReWTaMo high-entropy alloy prepared in Example 1; Fig. 3 (b) is the optical microstructure diagram of the ReWTaMoNb _0.2 high-entropy alloy prepared in Example 2; Fig. 3(c) is the optical microstructure diagram of the ReWTaMoNb _0.5 high-entropy alloy prepared in Example 3; Figure 3(d) is the optical microstructure diagram of the ReWTaMoNb _0.8 high-entropy alloy prepared in Example 4; Figure 3( e) is an optical microstructure diagram of the ReWTaMoNb high-entropy alloy prepared in Example 5.

Detailed ways

Specific embodiments of the present invention are described in detail below, which, as a part of the description, illustrate the principle of the present invention through examples, and other aspects, features and advantages of the present invention will become clear through the detailed description.

Fig. 1 is a process flow chart of the present invention for preparing high-density ReWTaMoNb _X high-entropy alloy materials.

Example 1:

Preparation of ReWTaMo high-entropy alloys. The specific steps are as follows:

(1) Mixing: Weigh 5.2794g of Re powder, 4.9750g of W powder, 4.9853g of Ta powder, and 2.5935g of Mo powder with a purity of 99.9% (Re/W/Ta/Mo/Nb molar ratio is 1.05:1:1.02 :1:0), the particle size of the powder is 20 μm; use a light ball mill to mix evenly for 30 hours to obtain a mixed powder.

(2) Preparation of prefabricated block: put the mixed powder obtained in step 1 into a WC mold, and perform cold high-pressure molding (pressure 300 MPa) with a tablet press for 10 minutes to obtain a prefabricated block.

(3) Preparation of high-entropy alloys by electric arc melting: close the furnace door to vacuumize, and then pass 99.999% high-purity argon gas to make the pressure in the furnace reach -0.01MPa relative to the standard atmospheric pressure, and quickly start the arc to reduce the output power. Adjust to 45%-50% (current: 225-250A) for smelting for 2 minutes. Afterwards, the sample was turned over and remelted twice (the output power of each remelting was adjusted to 45%-50%, and the melting time was 2.5min), and then rapidly cooled to room temperature to obtain the ReWTaMo high-entropy alloy.

The obtained ReWTaMo high-entropy alloy has a density of 16.77g/cm ³ and a hardness of 6402MPa.

Example 2:

Preparation of ReWTaMoNb _0.2 . The specific steps are as follows:

(1) Mixing: Weigh 5.0280g of Re powder, 7.7199g of W-Mo alloy powder, 4.7410g of Ta powder, and 0.5023g of Nb powder with a purity of 99.9% (Re/W/Ta/Mo/Nb molar ratio is 1: 1.02:0.97:1.02:0.2), the particle size of the powder is 2 μm; use a light ball mill to mix evenly for 24 hours to obtain a mixed powder.

(2) Preparation of prefabricated block: put the mixed powder obtained in step 1 into a WC mould, and perform cold high-pressure molding (pressure 350 MPa) using a tablet press, with a holding time of 8 minutes to obtain a prefabricated block.

(3) Preparation of high-entropy alloys by electric arc melting: close the furnace door to vacuumize, and then pass 99.999% high-purity argon gas to make the pressure in the furnace reach -0.01MPa relative to the standard atmospheric pressure, and quickly start the arc to reduce the output power. Adjust to 45%-50% (current: 225-250A) for smelting for 2.5 minutes. Afterwards, the sample was turned over, remelted twice (the output power of each remelting was adjusted to 45%-50%, and the melting time was 2min), and then rapidly cooled to room temperature to obtain a ReWTaMoNb _0.2 high-entropy alloy.

The resulting ReWTaMoNb _0.2 high-entropy alloy has a density of 16.31 g/cm ³ and a hardness of 6257 MPa.

Example 3:

Preparation of ReWTaMoNb _0.5 . The specific steps are as follows:

(1) Mixing: take by weighing 99.9% of Re powder 5.0280g, W powder 4.7263g, Ta powder 4.8876g, Mo powder 2.7232g, Nb powder 1.2558g (Re/W/Ta/Mo/Nb mol ratio is 1:0.95:1:1.05:0.5), the particle size of the powder is 10 μm; use a light ball mill to mix evenly for 20 hours to obtain a mixed powder.

(2) Preparation of prefabricated block: put the mixed powder obtained in step 1 into a WC mold, and perform cold high-pressure molding (pressure 400 MPa) with a tablet press for 5 minutes to obtain a prefabricated block.

(3) Preparation of high-entropy alloys by electric arc melting: close the furnace door to vacuumize, and then pass 99.999% high-purity argon gas to make the pressure in the furnace reach -0.01MPa relative to the standard atmospheric pressure, and quickly start the arc to reduce the output power. Adjust to 45%-50% (current: 225-250A) for smelting for 3 minutes. Afterwards, the sample was turned over and remelted once (the output power of each remelting was adjusted to 45%-50%, and the melting time was 3 minutes), and then rapidly cooled to room temperature to obtain a ReWTaMoNb _0.5 high-entropy alloy.

The obtained ReWTaMoNb _0.5 high-entropy alloy has a density of 15.74 g/cm ³ and a hardness of 6105 MPa.

Example 4:

Preparation of ReWTaMoNb _0.8 . The specific steps are as follows:

(1) Mixing: Weigh 5.028g of Re powder, 7.5685g of W-Mo powder, 5.1320g of Ta powder, and 2.0093g of Nb powder with a purity of 99.9% (Re/W/Ta/Mo/Nb molar ratio is 1:1 :1.05:1:0.8), the particle size of the powder is 5 μm; use a light ball mill to mix evenly for 26 hours to obtain a mixed powder.

(2) Preparation of prefabricated block: put the mixed powder obtained in step 1 into a WC mold, and perform cold high-pressure molding (pressure 380 MPa) with a tablet press for 6 minutes to obtain a prefabricated block.

(3) Preparation of high-entropy alloys by electric arc melting: close the furnace door to vacuumize, and then pass 99.999% high-purity argon gas to make the pressure in the furnace reach -0.01MPa relative to the standard atmospheric pressure, and quickly start the arc to reduce the output power. Adjust to 45%-50% (current: 225-250A) for smelting for 2 minutes. Afterwards, the sample was turned over and remelted once (the output power of each remelting was adjusted to 45%-50%, and the melting time was 3 minutes), and then rapidly cooled to room temperature to obtain the ReWTaMoNb _0.8 high-entropy alloy.

The resulting ReWTaMoNb _0.8 high-entropy alloy has a density of 15.27 g/cm ³ and a hardness of 5933 MPa.

Example 5:

Preparation of ReWTaMoNb. The specific steps are as follows:

(1) Mixing: take by weighing 99.9% of Re powder 5.0280g, W powder 4.9750g, Ta powder 4.8876g, Mo powder 2.5935g, Nb powder 2.5116g (Re/W/Ta/Mo/Nb mol ratio is 1:1:1:1:1), the particle size of the powder is 10 μm; use a light ball mill to mix evenly for 28 hours to obtain a mixed powder.

(2) Preparation of prefabricated block: put the mixed powder obtained in step 1 into a WC mold, and perform cold high-pressure molding (pressure 350 MPa) with a tablet press for 5 minutes to obtain a prefabricated block.

(3) Preparation of high-entropy alloys by electric arc melting: close the furnace door to vacuumize, and then pass 99.999% high-purity argon gas to make the pressure in the furnace reach -0.01MPa relative to the standard atmospheric pressure, and quickly start the arc to reduce the output power. Adjust to 45%-50% (current: 225-250A) for smelting for 3 minutes. Afterwards, the sample was turned over, and remelted twice (the output power of each remelting was adjusted to 45%-50%, and the melting time was 2.5min), and then rapidly cooled to room temperature to obtain a ReWTaMoNb high-entropy alloy.

The obtained ReWTaMoNb high-entropy alloy had a density of 15.02 g/cm ³ and a hardness of 5754 MPa.

Fig. 2 is the XRD pattern of the ReWTaMoNb _X high-entropy alloy of different Nb contents; Wherein: Fig. 2 (curve a) is the XRD pattern of the ReWTaMo high-entropy alloy prepared in Example 1; Fig. 2 (curve b) is prepared in Example 2 The XRD pattern of the obtained ReWTaMoNb _0.2 high-entropy alloy; Figure 2 (curve c) is the XRD pattern of the ReWTaMoNb _0.5 high-entropy alloy prepared in Example 3; Figure 2 (curve d) is the ReWTaMoNb _0.8 high-entropy alloy prepared in Example 4 XRD pattern of the alloy; FIG. 2 (curve e) is the XRD pattern of the ReWTaMoNb high-entropy alloy prepared in Example 5. It can be seen from the figure that the WReTaMoNbx high-entropy alloy is mainly composed of a simple solid solution phase with a body-centered cubic structure.

Fig. 3 is the optical microstructure diagram of the ReWTaMoNb _X high-entropy alloy with different Nb contents; wherein: Fig. 3 (a) is the optical microstructure diagram of the ReWTaMo high-entropy alloy prepared in Example 1; Fig. 3 (b) is The optical microstructure diagram of the ReWTaMoNb _0.2 high-entropy alloy prepared in Example 2; Figure 3(c) is the optical microstructure diagram of the ReWTaMoNb _0.5 high-entropy alloy prepared in Example 3; Figure 3(d) is the embodiment 4 Optical microstructure diagram of the prepared ReWTaMoNb _0.8 high-entropy alloy; FIG. 3( e ) is an optical microstructure diagram of the ReWTaMoNb high-entropy alloy prepared in Example 5. It can be seen from the figure that the WReTaMoNbx high-entropy alloy matrix is dendrite, and the second phase is dispersed in the matrix in the form of particles.

Each raw material enumerated in the present invention, and the upper and lower limits of each raw material of the present invention, the interval value, and the upper and lower limits of process parameters (such as pressure, time, temperature, etc.), the interval value can realize the present invention, not herein A list of examples.

The above description is only a preferred embodiment of the present invention, and of course the scope of rights of the present invention cannot be limited by this. It should be pointed out that for those of ordinary skill in the art, they can also Several improvements and changes are made, and these improvements and changes are also regarded as the protection scope of the present invention.

Claims (7)

1. A high-density ReWTaMoNb _X high-entropy alloy material containing Re is characterized in that: the composition of the alloy material is ReWTaMoNb _X , and the mol ratio of any two elements in the Re/W/Ta/Mo element in the alloy is 0.95～ 1.05, the molar ratio of Nb to any other element x=0-1. 2. The high-density ReWTaMoNb _X high-entropy alloy material containing Re as claimed in claim 1, characterized in that: the gained high-entropy alloy material has high density and high hardness, the density is not less than 15g/cm ³ , and the hardness is not less than lower than 5700MPa. 3. the preparation method of the high-density ReWTaMoNb _X high-entropy alloy material containing Re as claimed in claim 1, is characterized in that, comprises the steps: Step 1. Mixing: Weigh Re, W-Mo, Ta, Nb metal powders according to the molar ratio of 0.95-1.05: 1.9-2.1: 0.95-1.05: 0-1, and mix them evenly by ball milling; the W-Mo metal powders It is a mixed powder of W powder and Mo powder with a molar ratio of 0.95-1.05:0.95-1.05, or a W-Mo alloy powder with a molar ratio of W and Mo of 0.95-1.05:0.95-1.05; Step 2, preparing prefabricated blocks: using cold high pressure forming technology to make the mixed powder prepared in step 1 into prefabricated blocks; Step 3, preparing high-entropy alloy by arc melting: using a high-vacuum non-consumable arc melting furnace to melt the prefabricated block into a master alloy ingot under the protection of high-purity argon. 4. the preparation method of the high-density ReWTaMoNb _X high-entropy alloy material containing Re as claimed in claim 3, is characterized in that: the purity of described Re, W-Mo, Ta, Nb metal powder is all greater than 99.9%, and powder The particle size distribution is 2-20μm; the mixing time is 20-30h. 5 . The method for preparing Re-containing high-density ReWTaMoNb _X high-entropy alloy material as claimed in claim 3, characterized in that: in the second step, the pressing pressure is 300-400 MPa, and the holding time is 5-10 min. 6. The method for preparing Re-containing high-density ReWTaMoNb _X high-entropy alloy material as claimed in claim 3, characterized in that: in the second step, the mold used for pressing is a WC cemented carbide mold. 7. the preparation method of the high-density ReWTaMoNb _X high-entropy alloy material containing Re as claimed in claim 3 is characterized in that: in the described step 3, the front and back sides are repeatedly smelted 2-3 times, and each smelting time is 2-3 times. 3min.