CN113235033B - A method for enhancing the hardness of high-entropy alloys by electric pulse treatment - Google Patents

Abstract

The invention relates to a method for enhancing the hardness of a high-entropy alloy by electric pulse treatment, and belongs to the technical field of alloy material strengthening and toughening treatment. The method is as follows: the Al _0.1 CoCrFeNi high-entropy alloy is subjected to electric pulse treatment, the times of electric pulse treatment is 5 to 20 times, the time of single electric pulse treatment is 0.1 s to 1 s, and the time of two adjacent electric pulse treatments is 0.1 s to 1 s. The time interval is 10s ~ 60s, the current density of the electric pulse treatment is 10A/mm ² ~ 100A/mm ² , and the current density of each electric pulse treatment is the same. After the electric pulse treatment, the treated Al _0.1 CoCrFeNi high entropy The alloy was naturally cooled to obtain Al _0.1 CoCrFeNi high-entropy alloy after electric pulse treatment. The method has the characteristics of short time, high efficiency and green, and can enhance the hardness of Al _0.1 CoCrFeNi high-entropy alloy.

Description

A method for enhancing the hardness of high-entropy alloys by electric pulse treatment

technical field

The invention relates to a method for enhancing the hardness of high-entropy alloys by electric pulse treatment, in particular to a method for enhancing the hardness of Al _0.1 CoCrFeNi high-entropy alloys by electric pulse treatment, and belongs to the technical field of alloy material strengthening and toughening treatment.

Background technique

In recent years, under the guidance of multi-component alloy design ideas, researchers have discovered new metal materials with both "structural disorder" and "chemical disorder" by changing and modulating the "configuration entropy" of the alloy system - high Entropy Alloy. Thermodynamically, high-entropy alloys have lower Gibbs free energy and thus exhibit higher phase and microstructure stability. Due to the lattice distortion effect of the structure, the high-entropy alloys exhibit slow or sluggish diffusion in terms of kinetics. In terms of performance, high-entropy alloys also exhibit compressive strength, toughness and thermal stability superior to conventional metallic materials. To sum up, the unique alloy design concept and significant high mixing entropy effect of high-entropy alloys make the high-entropy alloy solid solution alloys formed by them have great potential application value, and are expected to be used in heat-resistant and wear-resistant coatings, molds, etc. Lining, cemented carbide and superalloy and other fields.

At present, Al _0.1 CoCrFeNi is one of the widely studied high-entropy alloy systems, and studies have shown that Al _0.1 CoCrFeNi is a single-phase solid solution with a simple face-centered cubic (FCC) structure at high and low temperatures, and has excellent structural stability. In addition, the Al _0.1 CoCrFeNi high-entropy alloy also exhibits excellent mechanical properties of high impact toughness, high tensile strength and high plasticity. However, similar to other FCC high-entropy alloys, the disadvantage of Al _0.1 CoCrFeNi high-entropy alloy is its low hardness, which affects its application in practical scenarios.

In order to improve the problem of low hardness of Al _0.1 CoCrFeNi high-entropy alloys, traditional heat treatment can be used. The traditional heat treatment is generally to heat the alloy samples through heat conduction or heat radiation in a heating furnace. However, the traditional heat treatment requires long processing time and high energy consumption. In addition, in the long-term heating and cooling process, it is often accompanied by a large amount of energy loss. Therefore, the traditional heat treatment process is not an energy-saving and efficient process. Therefore, optimizing the processing technology of alloy materials and improving the energy utilization rate of the processing process need to be solved urgently.

As an instantaneous high-energy input technology, electrical pulse treatment can improve the microstructure of the alloy, thereby improving the performance of the alloy, and the electrical pulse treatment also has the advantages of high efficiency, economy, energy saving and environmental protection.

In the process of electrical pulse treatment, the Joule heating effect, electromigration effect (the directional movement of charged particles or holes under the action of an electric field), and skin effect (the current density in the cross-section of a high-frequency current passing through a conductor) caused by the pulse current The phenomenon of uneven direction distribution), the electron wind effect (the momentum generated by the violent collision of a large number of fast-moving free electrons and atoms), and the thermal compression stress (the stress caused by the asynchronous temperature rise and thermal expansion inside the material) will all produce material organization. big influence. Therefore, the coupling effects of electricity, heat, and force induced by high-density pulse current can rapidly improve the structure and properties of alloy materials in microseconds or milliseconds. The energy input effectively controls the microstructure of the alloy, thereby realizing the regulation of the alloy properties.

In order to solve the problems of long production cycle, high production cost and low energy utilization rate of traditional heat treatment, there is no relevant report on the method of using electric pulse to treat Al _0.1 CoCrFeNi high-entropy alloy and enhance its hardness.

SUMMARY OF THE INVENTION

In view of this, the purpose of the present invention is to provide a method for enhancing the hardness of high-entropy alloys by electric pulse treatment, specifically, to provide a method for enhancing the hardness of Al _0.1 CoCrFeNi high-entropy alloys by electric pulse treatment, the method has the advantages of short-term, The high-efficiency and green features can enhance the hardness of Al _0.1 CoCrFeNi high-entropy alloys.

In order to achieve the purpose of the present invention, the following technical solutions are provided.

A method for enhancing the hardness of high-entropy alloys by electric pulse treatment, the method steps are as follows:

The Al _0.1 CoCrFeNi high-entropy alloy is subjected to electric pulse treatment, the number of electric pulse treatment is 5 to 20 times, the time of single electric pulse treatment is 0.1s ~ 1s, and the time interval of two adjacent electric pulse treatments is 10s ~ 60s, the current density of the electric pulse treatment is 10A/mm ² ～ 100A/mm ² , and the current density of each electric pulse treatment is the same. After the electric pulse treatment, the treated Al _0.1 CoCrFeNi high-entropy alloy is naturally cooled to obtain Al _0.1 CoCrFeNi high-entropy alloy after electric pulse treatment.

The raw materials Al, Co, Cr, Fe and Ni used in the Al _0.1 CoCrFeNi high-entropy alloy are all metals with a purity greater than or equal to 99.9%.

Preferably, the electrical pulses output during the electrical pulse processing are in the form of pulsed square waves.

Preferably, the number of times of electric pulse treatment is 10 times.

Preferably, the time for a single electric pulse treatment is 0.5s.

Preferably, the time interval between two adjacent electric pulse treatments is 30s.

Preferably, the current density of the electrical pulse treatment is 90 A/mm ² .

beneficial effect

(1) A method for enhancing the hardness of high-entropy alloys by electric pulse treatment provided by the present invention is characterized in that the Al _0.1 CoCrFeNi high-entropy alloys are treated by means of electric pulses, and the time used is short, the efficiency is high, and the energy is saved. Therefore, the The method is fast, efficient and green; at the same time, the method can significantly improve the hardness of the Al _0.1 CoCrFeNi high-entropy alloy in a short time, which not only makes up for the deficiency of the Al _0.1 CoCrFeNi high-entropy alloy in hardness performance, but also avoids the traditional The disadvantages of heat treatment are long production cycle, high production cost and serious pollution.

(2) A method for enhancing the hardness of high-entropy alloys by electric pulse treatment provided by the present invention adopts electric pulse technology to treat Al _0.1 CoCrFeNi high-entropy alloys, and the coupling effect of thermal effect and non-thermal effect of electric pulses can greatly reduce Al _0.1 CoCrFeNi The recrystallization nucleation thermodynamic barrier of high-entropy alloys promotes the diffusion of solute atoms in high-entropy alloys, thereby shortening the local recrystallization time of high-entropy alloys, and also changing the preferred orientation of the crystal planes of high-entropy alloys. In addition, the improvement of the solute atomic diffusion ability of Al _0.1 CoCrFeNi HEA also enhances its own "chemical disorder" and "structural disorder", which eventually leads to the aggravation of the lattice distortion of the HEA at the micro-scale, which in turn affects the The hardness of the high-entropy alloy, the Al _0.1 CoCrFeNi high-entropy alloy obtained by the method of the present invention increases the hardness to some extent.

(3) A method for enhancing the hardness of high-entropy alloys by electric pulse treatment provided by the present invention, when the pulse form is a pulse square wave, the current density changes little during the electric pulse treatment process, and the energy during the electric pulse periodical continuous treatment process is small. The output is concentrated and stable, which can most effectively control the microstructural evolution of high-entropy alloys, which in turn affects the hardness changes of high-entropy alloys.

Description of drawings

FIG. 1 is a schematic diagram of the experimental apparatus for enhancing the hardness of Al _0.1 CoCrFeNi high-entropy alloys by electric pulse treatment in Examples 1-3.

FIG. 2 is the X-ray diffraction pattern of the as-cast Al _0.1 CoCrFeNi high-entropy alloy in Comparative Example 1 and the Al _0.1 CoCrFeNi high-entropy alloy after electric pulse treatment in Examples 1-3.

3 shows the Vickers hardness of the as-cast Al _0.1 CoCrFeNi high-entropy alloy in Comparative Example 1 and the Al _0.1 CoCrFeNi high-entropy alloy after electric pulse treatment in Examples 1 to 3.

Among them, 1-adjustment switch, 2-DC pulse power supply, 3-cathode clamp, 4-indenter, 5-Al _0.1 CoCrFeNi high-entropy alloy sample, 6- anode clamp.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments, but it is not intended to limit the patent of the present invention. In the following comparative examples and examples:

In the X-ray diffraction pattern test, the scanning angle range is 10°-100°, the scanning speed is 5°/min, and the test results are processed by the crystal structure analysis software MDI Jade 6.5.

The alloy hardness test was carried out with a Deka HV-1000Z automatic digital micro-Vickers hardness tester, and the test was carried out under a static load of 100g, and the duration was 10s. The selection method of Vickers hardness test points is to start from the center point of the alloy sample, and then select equidistantly along the straight line direction of up, down, left, and right, and select 10 Vickers hardness test points for each alloy sample to be tested. Hardness test, and finally take the average value.

The literatures [1-3] mentioned in Comparative Example 1 are:

Literature[1]: X.Xu,P.Liu,Z.Tang,A.Hirata,S.Song,T.Nieh,P.Liaw,C.Liu,M.Chen,Transmission electron microscopy characterization of dislocation structure ina face -centered cubic high-entropy alloy Al _0.1 CoCrFeNi, Acta Materialia 144(2018) 107-115.

Reference [2]: P.Yu, H.Cheng, L.Zhang, H.Zhang, Q.Jing, M.Ma, P.Liaw, G.Li, R.Liu, Effects of high pressure torsion on microstructures and properties of anAl _0.1 CoCrFeNi high-entropy alloy, Materials Science and Engineering: A 655(2016) 283-291.

Reference [3]: T. Yang, Z. Tang, X. Xie, R. Carroll, G. Wang, Y. Wang, KADahmen, PKLiaw, Y. Zhang, Deformation mechanisms of Al _0.1 CoCrFeNi at elevated temperatures, Materials Science and Engineering : A 684 (2017) 552-558.

Fig. 1 is a schematic diagram of the experimental device used in Examples 1 to 3 to enhance the hardness of Al _0.1 CoCrFeNi high-entropy alloys by electric pulse treatment; when in use, connect the cathode clamp 3 and anode clamp 6 at the output end of the DC pulse power supply 2 to the universal testing machine. On the indenter 4 at both ends of the compression mold, the Al _0.1 CoCrFeNi high-entropy alloy sample 5 is placed stably between the indenters 4 at both ends of the compression mold, and the indenter 4 at both ends of the compression mold is adjusted by the universal testing machine to make it and Al The upper and lower surfaces of the _0.1 CoCrFeNi high-entropy alloy sample 5 are in contact but no force is applied, and the current is adjusted by adjusting the switch 1.

Comparative Example 1

The Al _0.1 CoCrFeNi high-entropy alloy ingot prepared by vacuum suspension smelting was cut by wire cutting to take a cylindrical alloy sample with a diameter of 3.5 mm and a height of 7 mm, which was used to prepare the Al _0.1 CoCrFeNi high-entropy alloy ingot. , Co, Cr, Fe and Ni are metals with a purity greater than or equal to 99.9%; the upper and lower surfaces of the alloy sample are ground with 800 mesh, 1000 mesh, 1200 mesh and 1500 mesh metallographic sandpaper in turn, and then the alloy sample is polished. Mechanical polishing was performed to ensure that there were no scratches on the top and bottom of the alloy sample and the parallelism was good. It was an as-cast Al _0.1 CoCrFeNi high-entropy alloy without electrical pulse treatment.

The as-cast Al _0.1 CoCrFeNi high-entropy alloys of this comparative example without electrical pulse treatment were tested as follows:

(1) The X-ray diffraction pattern of the as-cast Al _0.1 CoCrFeNi high-entropy alloy without electrical pulse treatment in this comparative example was tested by X-ray diffractometer to characterize its crystal structure. The results are shown in (a) in Figure 2. The X-ray diffraction pattern of the as-cast Al _0.1 CoCrFeNi high-entropy alloy is described, and its X-ray diffraction peaks match those of the PDF standard card and the Al _0.1 CoCrFeNi high-entropy alloy reported in literature [1-3]. It can be seen that the as-cast Al _0.1 CoCrFeNi high-entropy alloy without electric pulse treatment in this comparative example is an FCC single-phase solid solution.

(2) Alloy hardness test, the results are shown in Figure 3, it can be seen that the Vickers hardness of the as-cast Al _0.1 CoCrFeNi high-entropy alloy without electrical pulse treatment in this comparative example is 171.4Hv.

Example 1

The same alloy sample as in Comparative Example 1 was used, and electric pulse treatment was applied to it; the electric pulse treatment parameters were as follows: the electric pulse output during the electric pulse treatment was in the form of a pulse square wave, and the number of electric pulse treatment was 10 times. The time of electric pulse treatment was 0.5s, the time interval of two adjacent electric pulse treatments was 30s, and the current density of each electric pulse treatment was 10A/mm ² . After the electric pulse treatment, the Al _0.1 CoCrFeNi high-entropy alloy sample was Natural cooling to obtain Al _0.1 CoCrFeNi high-entropy alloy after electric pulse treatment.

The following tests were performed on the Al _0.1 CoCrFeNi high-entropy alloy obtained in this example after the electric pulse treatment:

(1) The X-ray diffraction pattern of the Al _0.1 CoCrFeNi high-entropy alloy obtained in this example after electric pulse treatment was tested by an X-ray diffractometer to characterize its crystal structure. The result is shown in (b) in Figure 2, it can be seen : After electric pulse treatment with a current density of 10A/mm ² , the crystal structure of Al _0.1 CoCrFeNi high-entropy alloy has not changed significantly, and it still belongs to the FCC single-phase solid solution structure; Example After the 10A/mm ² electric pulse treatment, the relative intensities of the diffraction peaks of the Al _0.1 CoCrFeNi high-entropy alloy in the (111) and (200) crystal plane directions were significantly enhanced, that is, the present example was treated with 10 A/mm ² electric pulse. The Al _0.1 CoCrFeNi high-entropy alloys have obvious preferred orientations on the (111) and (200) planes.

(2) Alloy hardness test, the results are shown in Figure 3, it can be seen that the Vickers hardness of the Al _0.1 CoCrFeNi high-entropy alloy treated with electric pulses with a current density of 10A/mm ² in this example is 194.7Hv, which is similar to that of Comparative Example 1. Compared with the hardness of the as-cast Al _0.1 CoCrFeNi high-entropy alloy treated with electric pulse, the hardness is increased by about 13.5%, which has an obvious improvement effect.

Example 2

The same alloy sample as in Comparative Example 1 was used, and electric pulse treatment was applied to it; the electric pulse treatment parameters were as follows: the electric pulse output during the electric pulse treatment was in the form of a pulse square wave, and the number of electric pulse treatment was 10 times. The time of electric pulse treatment was 0.5s, the time interval of two adjacent electric pulse treatments was 30s, and the current density of each electric pulse treatment was 90A/mm ² . After the electric pulse treatment, the Al _0.1 CoCrFeNi high-entropy alloy sample was Natural cooling to obtain Al _0.1 CoCrFeNi high-entropy alloy after electric pulse treatment.

The following tests were performed on the Al _0.1 CoCrFeNi high-entropy alloy obtained in this example after the electric pulse treatment:

(1) The X-ray diffraction pattern of the Al _0.1 CoCrFeNi high-entropy alloy obtained in this example after electric pulse treatment was tested by X-ray diffractometer to characterize its crystal structure, and the result is shown in (c) in Figure 2. : After electric pulse treatment with a current density of 90A/mm ² , the Al _0.1 CoCrFeNi high-entropy alloy still belongs to the FCC single-phase solid solution structure; ² After the electric pulse treatment, with the increase of the electric pulse density, the relative intensities of the diffraction peaks of Al _0.1 CoCrFeNi high-entropy alloys in the (111), (200) and (220) crystal plane directions increase accordingly. The preferred orientations of Al _0.1 CoCrFeNi high-entropy alloys in the (111), (200) and (220) plane directions change with increasing pulse current density in the range of densities from 10 A/mm ² to 90 A/mm ² more obvious.

(2) Alloy hardness test, the results are shown in Figure 3, it can be seen that the Vickers hardness of the Al _0.1 CoCrFeNi high-entropy alloy treated with electric pulses at a current density of 90 A/mm ² in this example is 251.0 Hv, which is not comparable to that of Comparative Example 1. Compared with the as-cast Al _0.1 CoCrFeNi high-entropy alloy treated with electric pulses, the hardness of the Al _0.1 CoCrFeNi high-entropy alloy obtained in this example is increased by about 46.4%, which is similar to the hardness of the Al _0.1 CoCrFeNi high-entropy alloy obtained in Example 1. The ratio is improved by about 28.9%.

Example 3

The same alloy sample as in Comparative Example 1 was used, and electric pulse treatment was applied to it; the electric pulse treatment parameters were as follows: the electric pulse output during the electric pulse treatment was in the form of a pulse square wave, and the number of electric pulse treatment was 10 times. The electric pulse treatment time was 0.5s, the time interval between two adjacent electric pulse treatments was 30s, and the current density of each electric pulse treatment was 100A/mm ² . After the electric pulse treatment, the Al _0.1 CoCrFeNi high-entropy alloy sample was Natural cooling to obtain Al _0.1 CoCrFeNi high-entropy alloy after electric pulse treatment.

The following tests were performed on the Al _0.1 CoCrFeNi high-entropy alloy obtained in this example after the electric pulse treatment:

(1) The X-ray diffraction pattern of the Al _0.1 CoCrFeNi high-entropy alloy obtained in this example after electric pulse treatment was tested by an X-ray diffractometer to characterize its crystal structure. The result is shown in (d) in Figure 2, which shows that : After electric pulse treatment with a current density of 100A/mm ² , the Al _0.1 CoCrFeNi high-entropy alloy still belongs to the FCC single-phase solid solution structure; After 100A/mm ² electric pulse treatment, with the continuous increase of electric pulse density, the relative intensity of the diffraction peak of Al _0.1 CoCrFeNi high-entropy alloy in the (200) crystal plane direction continued to increase, while the Al _0.1 CoCrFeNi high-entropy alloy in (200) The relative intensities of the diffraction peaks in the 111) and (220) crystal plane directions tended to weaken with the increase of the pulse current density.

(2) Alloy hardness test, the results are shown in Figure 3, it can be seen that the Vickers hardness of the Al _0.1 CoCrFeNi high-entropy alloy treated by electric pulse with a current density of 100A/mm ² in this example is 212.8Hv, which is not comparable to that of Comparative Example 1. Compared with the as-cast Al _0.1 CoCrFeNi high-entropy alloy treated with electric pulse, the hardness of the Al _0.1 CoCrFeNi high-entropy alloy obtained in this example is increased by about 24.2%, which is similar to the hardness of the Al _0.1 CoCrFeNi high-entropy alloy obtained in Example 1. The ratio is increased by about 9.3%, and the hardness of the Al _0.1 CoCrFeNi high-entropy alloy obtained in Example 2 is decreased by 38.2 Hv.

To sum up, the present invention adopts electric pulse treatment of Al _0.1 CoCrFeNi high-entropy alloy, which is convenient to operate, takes less time, and is environmentally friendly; in addition, after the as-cast Al _0.1 CoCrFeNi high-entropy alloy is treated by electric pulse, the current density is 10A/ In the range of mm ² to 100A/mm ² , the hardness of Al _0.1 CoCrFeNi HEA was improved, and in the range of 10 A/mm ² to 90 A/mm ² , with the increase of pulse current density, the treated Al _0.1 The hardness of CoCrFeNi high-entropy alloy also increases; and when the current density is 90A/mm ² , the hardness of the Al _0.1 CoCrFeNi high-entropy alloy obtained by the treatment is even better than that of the Al _0.1 CoCrFeNi high-entropy alloy after the current density is 100 A/mm ² . hardness.

The present invention includes but is not limited to the above embodiments, and any equivalent replacement or partial improvement made under the spirit of the present invention will be regarded as within the protection scope of the present invention.

Claims (7)

1. A method for enhancing the hardness of a high-entropy alloy by electric pulse treatment is characterized by comprising the following steps: the method comprises the following steps:

mixing Al_0.1The CoCrFeNi high-entropy alloy is subjected to electric pulse treatment, the frequency of the electric pulse treatment is 5-20 times, the time of single electric pulse treatment is 0.1-1 s, the time interval of two adjacent electric pulse treatments is 10-60 s, and the current density of the electric pulse treatment is 10A/mm²～100A/mm²And the current density of each electric pulse treatment is the same, and after the electric pulse treatment is finished, the treated Al is added_0.1The CoCrFeNi high-entropy alloy is naturally cooled to obtain Al after electric pulse treatment_0.1A CoCrFeNi high entropy alloy;

the Al is_0.1Raw materials Al, Co, Cr, Fe and for CoCrFeNi high-entropy alloyThe Ni is metal with the purity of more than or equal to 99.9 percent.

2. The method for enhancing the hardness of the high-entropy alloy by electric pulse treatment according to claim 1, wherein the electric pulse treatment comprises the following steps: the electric pulse output in the electric pulse treatment process is in the form of pulse square waves.

3. The method for enhancing the hardness of the high-entropy alloy by electric pulse treatment according to claim 1, wherein the electric pulse treatment comprises the following steps: the number of electric pulse treatments was 10.

4. The method for enhancing the hardness of the high-entropy alloy by electric pulse treatment according to claim 1, wherein the electric pulse treatment comprises the following steps: the time for single electrical pulse treatment was 0.5 s.

5. The method for enhancing the hardness of the high-entropy alloy by electric pulse treatment according to claim 1, wherein the electric pulse treatment comprises the following steps: the time interval between two adjacent electric pulse treatments was 30 s.

6. A method for enhancing the hardness of a high-entropy alloy by electric pulse treatment according to claim 1, wherein: the current density of the electric pulse treatment was 90A/mm²。

7. The method for enhancing the hardness of the high-entropy alloy by electric pulse treatment according to claim 1, wherein the electric pulse treatment comprises the following steps: the electric pulse output in the electric pulse treatment process is in the form of pulse square waves;

the number of electric pulse treatments was 10;

the time of single electric pulse treatment is 0.5 s;

the time interval between two adjacent electric pulse treatments is 30 s;

the current density of the electric pulse treatment was 90A/mm²。

Images