A (FeCoNiCrMn)Si high-entropy silicide with excellent zinc solution corrosion resistance and its preparation method

Abstract

The present invention discloses a (FeCoNiCrMn)Si high-entropy silicide with excellent zinc solution corrosion resistance and a preparation method thereof. Fe, Co, Ni, Cr, Mn, and Si are selected as raw materials, and the component composition of their atomic ratios is as follows: Si accounts for 50%, Fe accounts for 8-12%, Co accounts for 10-13%, Ni accounts for 6-13%, Cr accounts for 8-12%, and Mn accounts for 7-11%. The as-cast button ingot is obtained by vacuum melting, and then homogenization annealing is carried out to prepare a (FeCoNiCrMn)Si high-entropy silicide with uniform composition. The corrosion rate of the (FeCoNiCrMn)Si high-entropy silicide obtained in the examples of the present invention in liquid zinc at 450 degrees for 10 days is less than 5.5 μm / day, far better than 115.44 μm / day of 316 stainless steel and better than 5.77 μm / day of MoB-CoCr material. However, the cost is lower than that of MoB-CoCr material, and it is expected to replace MoB-CoCr material. Moreover, the raw materials of the alloy product have a wide source, the preparation method is simple, and the product has a wide range of uses.

Description

Technical Field

[0001] The present invention relates to the technical field of metal materials, and in particular to a (FeCoNiCrMn)Si high-entropy silicide with excellent zinc liquid corrosion resistance and a preparation method thereof. Background Art

[0002] In the field of hot-dip galvanizing, galvanized steel sheets are widely used in the automotive industry due to their resistance to atmospheric corrosion and low production costs. However, an important problem of hot-dip galvanizing is the severe corrosion of underwater equipment (i.e., rollers, support bearings, sinkers, support roller arms, and nose tips). The corrosion and frequent failures of such equipment lead to serious production downtime and high maintenance costs. Therefore, research on excellent corrosion-resistant materials in hot-dip galvanizing has received great attention. At present, a variety of zinc corrosion-resistant materials have been developed, such as MoB-CoCr, WC-Co, FeB alloys, FeSi alloys, etc. Among them, iron-silicon compounds have the potential to be used as zinc corrosion-resistant materials in the field of hot-dip galvanizing due to their low cost and difficulty in reacting with zinc liquid. However, the greater brittleness of iron-silicon compounds themselves hinders their application in zinc corrosion resistance.

[0003] In recent years, high-entropy materials prepared based on multi-principal element design have been widely studied. Compared with traditional alloys, high-entropy materials have comprehensive properties such as high strength, good ductility, corrosion resistance, thermal stability, and high-temperature oxidation resistance due to their thermodynamic high-entropy effect, kinetic hysteresis diffusion effect, crystallographic lattice distortion effect, and performance cocktail effect. The multi-principal element design concept provides a new direction for the design of iron-silicon compounds with both corrosion resistance and toughness. Silicon compounds such as FeSi, CoSi, and MnSi have good resistance to zinc liquid corrosion. The atomic radius and valence electron number of Fe, Co, Ni, Cr, and Mn elements are similar. Through the multi-principal element alloying method, Fe, Co, Ni, Cr, and Mn can be replaced with each other, which is expected to form a low-cost (FeCoNiCrMn)Si high-entropy silicide that combines zinc corrosion resistance and toughness. Summary of the Invention

[0004] The present invention aims to provide a (FeCoNiCrMn)Si high entropy silicide having excellent corrosion resistance to zinc liquid, wherein the crystal structure thereof is a B20 structure. Another object of the present invention is to provide a method for preparing the above-mentioned (FeCoNiCrMn)Si high entropy silicide.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows: For a (FeCoNiCrMn)Si high-entropy silicide with excellent zinc solution corrosion resistance, the atomic ratio composition is as follows: Si accounts for 50%, Fe accounts for 8-12%, Co accounts for 10-13%, Ni accounts for 6-13%, Cr accounts for 8-12%, and Mn accounts for 7-11%. The sum of the atomic percentages of the above components is 100%.

[0006] Further, the (FeCoNiCrMn)Si high-entropy silicide is composed of a double B20 phase.

[0007] Another aspect of the present invention provides a method for preparing the above (FeCoNiCrMn)Si high-entropy silicide, including the following steps:

[0008] Step 1, weigh Fe, Co, Ni, Cr, Mn, and Si particles according to the atomic ratio;

[0009] Step 2, use a non-consumable vacuum melting furnace to melt the particles into button ingots;

[0010] Step 3, perform homogenization annealing on the button ingots.

[0011] Further, for the (FeCoNiCrMn)Si high-entropy silicide with excellent zinc solution corrosion resistance, Fe, Co, Ni, Cr, Mn, and Si particles with a purity of 99.99% are used as the components.

[0012] Further, when weighing samples in Step 1, considering that Mn is volatile, 5% more Mn is added to make up for the loss. After weighing the samples, place them in the vacuum melting furnace from bottom to top in the order of Mn, Si, Ni, Co, Fe, and Cr.

[0013] Further, before melting in Step 2, a gas washing operation is required. After the vacuum is pumped to -5×10 -3 Pa, high-purity argon with a purity of 99.99% is filled into the furnace until the internal pressure is -0.02 MPa. After standing for 10 s, perform the next gas washing, and this process is repeated 3 times. The voltage used during melting is 70 V, the current is 100-150 A, and the time is 1 min. When the material is completely melted, turn on the magnetic stirring function, and the magnetic stirring current is 20 A. Repeat the melting 5 times to obtain button ingots.

[0014] Further, in order to remove the impurity phases that appear during the solidification process, in Step 3, the ingot after vacuum melting is placed at 800 degrees for homogenization annealing for 48 h to obtain a high-entropy silicide with a uniform composition of double B20 phase.

[0015] Compared with the prior art, based on the design concept of multi-principal elements, Co, Ni, Cr, and Mn elements are added to the iron-silicon compound, allowing Fe, Co, Ni, Cr, and Mn to replace each other, and finally a low-cost (FeCoNiCrMn)Si high-entropy silicide with excellent zinc corrosion resistance is successfully prepared.

[0016] In the present invention, a high-vacuum non-consumable arc melting furnace is used to melt the raw materials into button ingots under the protection of high-purity argon gas, and homogenization annealing is carried out to obtain the (FeCoNiCrMn)Si high-entropy silicide. The corrosion rate of the (FeCoNiCrMn)Si high-entropy silicide obtained in the example of the present invention in liquid zinc at 450 °C for 10 days is lower than 5.5 μm / day, far better than 115.44 μm / day of 316 stainless steel and better than 5.77 μm / day of MoB-CoCr material. However, the cost is much lower than that of MoB-CoCr material, and it is expected to replace MoB-CoCr material. Moreover, the raw materials of the alloy product have a wide source, the preparation method is simple, and it has a broad application prospect in the field of hot-dip galvanizing. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 XRD diagram of Example 1 of the present invention

[0018] Figure 2 Scanning electron microscope diagram of Example 1 of the present invention

[0019] Figure 3 Cross-sectional diagram of Example 1 of the present invention after being corroded in zinc liquid at 450 °C for 10 days

[0020] Figure 4 Corrosion rate diagram of Examples 1-4 of the present invention in zinc liquid at 450 °C DETAILED DESCRIPTION OF THE INVENTION

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with 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, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022]

Example 1

[0023] A (FeCoNiCrMn)Si high-entropy silicide with excellent zinc liquid corrosion resistance and its preparation method include the following steps:

[0024] (1) Sample preparation step

[0025] (FeCoNiCrMn)Si high-entropy silicide component atomic ratio composition is as follows: Fe accounts for 10%, Co accounts for 10%, Ni accounts for 6 - 13%, Cr accounts for 10%, Mn accounts for 10%, and Si accounts for 50%. The purity of the reaction raw material Fe, Co, Ni, Cr, Mn, Si particles is above 99.99%; considering the volatility of Mn, 5% more Mn is added during weighing to make up for the loss.

[0026] (2) Melting step

[0027] First, place the sample into the melting furnace in the order of Mn, Si, Co, Ni, Fe, Cr from bottom to top, then perform a gas washing operation, evacuate to at least 5×10 -3 MPa, then introduce high-purity argon gas into the furnace until the furnace pressure is -0.02 MPa. After standing for 10 s, perform the next gas washing, and repeat this process 3 times; the voltage used during melting is 70 V. To prevent liquid splashing, while keeping the sample in a rolling liquid state, the current should be as much as possible between 100 - 150 A. When the material is completely melted, turn on the magnetic stirring function, and the magnetic stirring current is 20 A. Each melting is for 1 minute, then slowly reduce it to zero, and use a manipulator to turn the sample over and repeat melting more than 5 times to obtain a uniform structure.

[0028] (3) Homogenization annealing step

[0029] First, polish the surface of the button ingot after vacuum melting, then clean it by ultrasonic cleaning, seal it in a quartz test tube, and finally place the quartz test tube in an annealing furnace at 800 degrees for 48 h to ensure complete homogenization of the material.

[0030] (4) Microstructure observation

[0031] Cut the button ingot into experimental samples. Use wire cutting technology to cut 12 mm×12 mm×4 mm block samples from the alloy button prepared by arc melting. Subsequently, use waterproof sandpapers of 400#, 600#, 800#, 1000#, and 1200# to grind until there are no electro-etching pits on the sample surface, and then polish with diamond polishing paste with a particle size of 1.5 microns until no obvious scratches are seen under an optical microscope. After the treated sample is cleaned with alcohol in an ultrasonic generator and dried, measure XRD. As Figure 1 , it can be seen from the XRD pattern that the sample consists of two B20 phases. After testing XRD, etch the sample with an etchant (HF:HNO3:H2O = 1:3:4), and the etching time is 5 - 10 s. Observe the sample after metallographic etching under a scanning electron microscope and perform energy spectrum analysis. The results are as Figure 2As shown, the ratio of (FeCoNiCrMn):Si in the dark and light phases is almost 1:1. Combining with XRD analysis, it can be concluded that both phases in the (FeCoNiCrMn)Si high-entropy silicide are of B20 structure, where Fe, Co, Ni, Cr, and Mn replace each other within the same sublattice, and Si occupies another sublattice alone.

[0032] (5) Fracture toughness measurement

[0033] Cut 12mm×12mm×4mm bulk samples again, and then successively grind them with waterproof sandpapers of 400#, 600#, 800#, 1000#, and 1200# until there are no electro-erosion pits on the sample surface. Then polish them with diamond polishing paste with a particle size of 1.5 microns until no obvious scratches can be seen under an optical microscope. Place them under an HVS-1000 microhardness tester and make 10 points under loads of 100g, 300g, and 500g. Measure the half diagonal length a and the average crack length L under a scanning electron microscope, and calculate the fracture toughness K of the high-entropy silicide in Example 1. IC Reaches 2.42±0.05MPa·m 0.5 , compared with the FeSi compound, the fracture toughness value does not decrease.

[0034] (6) Zinc solution corrosion resistance test

[0035] Cut 9 12mm×5mm×4mm bulk samples, and then successively grind them with waterproof sandpapers of 400#, 600#, 800#, and 1200# until there are no electro-erosion pits on the sample surface. Then polish them with diamond polishing paste with a particle size of 1.5 microns until no obvious scratches can be seen under an optical microscope. Measure the thickness of the sample under a scanning electron microscope and take the average value d0 after measuring 10 times. Then immerse the samples in a zinc bath at 450 degrees, take them out on the 3rd, 5th, and 10th days respectively, take out 3 samples each time, strip the zinc on the sample surface, and after embedding the samples, grind them with waterproof sandpapers of 400#, 600#, 800#, 1000#, and 1200# until there are no electro-erosion pits on the sample surface. Then polish them with diamond polishing paste with a particle size of 1.5 microns until no obvious scratches can be seen under an optical microscope, and then place them under a scanning electron microscope to measure the thickness of the sample. Take the average thickness of the three parallel samples as the thickness d of the corroded sample, and observe the corroded microstructure. The microstructure diagram of the sample corroded in 450-degree zinc solution for 10 days is as Figure 3 shown. The corrosion rate of the (FeCoNiCrMn)Si high-entropy silicide obtained in Example 1 in 450-degree zinc solution for 10 days is 4.8μm / day, as Figure 4 shown.

[0036]

Example 2

[0037] The preparation method of Example 2 is the same as that of Example 1 except for the sample preparation step in step (1). The rest are the same and will not be elaborated here. The sample preparation step in step 1 of Example 2: The atomic ratio composition of the (FeCoNiCrMn)Si high-entropy silicide component is as follows: Fe accounts for 11%, Co accounts for 11%, Ni accounts for 6%, Cr accounts for 11%, Mn accounts for 11%, and Si accounts for 50%. The purity of the reaction raw material particles of Fe, Co, Ni, Cr, Mn, and Si is above 99.99%; considering that Mn is volatile, 5% more Mn is added during weighing to make up for the loss. The fracture toughness K of the high-entropy silicide in Example 2 IC is 2.39 ± 0.09 MPa·m 0.5 . The corrosion rate of the (FeCoNiCrMn)Si high-entropy silicide obtained in Example 2 in the zinc liquid at 450 degrees for 10 days is 5.0 μm / day, as Figure 4 shown

[0038]

Example 3

[0039] The preparation method of Example 3 is the same as that of Example 1 except for the sample preparation step in step (1). The rest are the same and will not be elaborated here. The sample preparation step in step 1 of Example 3: The sample preparation step: The atomic ratio composition of the (FeCoNiCrMn)Si high-entropy silicide component is as follows: Fe accounts for 12%, Co accounts for 12%, Ni accounts for 7%, Cr accounts for 12%, Mn accounts for 7%, and Si accounts for 50%. The purity of the reaction raw material particles of Fe, Co, Ni, Cr, Mn, and Si is above 99.99%; considering that Mn is volatile, 5% more Mn is added during weighing to make up for the loss. The fracture toughness K of the high-entropy silicide in Example 3 IC is 2.39 ± 0.08 MPa·m 0.5 . The corrosion rate of the (FeCoNiCrMn)Si high-entropy silicide obtained in Example 3 in the zinc liquid at 450 degrees for 10 days is 4.9 μm / day, as Figure 4 shown

[0040]

Example 4

[0041] The preparation method of Example 4 is the same as that of Example 1 except for the sample preparation step in step (1). The rest are the same and will not be elaborated here. The sample preparation step in step 1 of Example 3: The sample preparation step: The atomic ratio composition of the (FeCoNiCrMn)Si high-entropy silicide component is as follows: Fe accounts for 8%, Co accounts for 13%, Ni accounts for 13%, Cr accounts for 8%, Mn accounts for 8%, and Si accounts for 50%. The purity of the reaction raw material particles of Fe, Co, Ni, Cr, Mn, and Si is above 99.99%; considering that Mn is volatile, 5% more Mn is added during weighing to make up for the loss. The fracture toughness K of the high-entropy silicide in Example 4 ICIt is 2.38 ± 0.06 MPa·m 0.5 . The corrosion rate of the (FeCoNiCrMn)Si high-entropy silicide obtained in Example 4 in zinc liquid at 450 °C for 10 days is 5.4 μm / day, as Figure 4 shown.

[0042] In summary, (FeCoNiCrMn)Si high-entropy silicides have been obtained in multiple groups of implementation cases. The corrosion rate in zinc liquid at 450 °C for 10 days is less than 5.5 μm / day, far better than 115.44 μm / day of 316 stainless steel and also better than 5.77 μm / day of MoB-CoCr material. However, the cost is lower than that of MoB-CoCr material, and it is expected to replace MoB-CoCr material. Moreover, the raw materials of the alloy product are widely sourced, the preparation method is simple, and the product has a wide range of uses.

[0043] The above is only an illustration of the best embodiment of the present invention, but it should not be construed as a limitation of the claims. The present invention is not limited to the above embodiments, and its components are allowed to have some changes. All changes made within the protection scope of the independent claims of the present invention are within the protection scope of the present invention.

Claims

1. A (FeCoNiCrMn)Si high-entropy silicide with excellent zinc solution corrosion resistance, characterized in that: The high-entropy silicide is composed of a double B20 phase, and the atomic ratios of the components are as follows: Si accounts for 50%, Fe accounts for 8-12%, Co accounts for 10-13%, Ni accounts for 6-13%, Cr accounts for 8-12%, and Mn accounts for 7-11%; the high-entropy silicide is obtained by subjecting the ingot after vacuum melting to homogenization annealing at 800 °C for 48 hours to obtain a double B20 phase high-entropy silicide with uniform composition.

2. The preparation method of the (FeCoNiCrMn)Si high-entropy silicide according to claim 1, characterized in that It includes the following steps: Step 1, weigh Fe, Co, Ni, Cr, Mn, and Si particles according to the atomic ratios. Step 2, melt the particles into a button ingot using a non-consumable vacuum melting furnace. Step 3, perform homogenization annealing on the button ingot.

3. The preparation method of the (FeCoNiCrMn)Si high-entropy silicide according to claim 2, characterized in that: The composition of the (FeCoNiCrMn)Si high-entropy silicide uses Fe, Co, Ni, Cr, Mn, and Si particles with a purity of 99.99% each.

4. The preparation method of the (FeCoNiCrMn)Si high-entropy silicide according to claim 2, characterized in that: When weighing the samples, considering that Mn is volatile, an additional 5% of Mn is added to make up for the loss. After weighing is completed, place them in the vacuum melting furnace in the order of Mn, Si, Ni, Co, Fe, and Cr from bottom to top.

5. The preparation method of the (FeCoNiCrMn)Si high-entropy silicide according to claim 2, characterized in that: Before melting, a gas washing operation needs to be carried out. After the vacuum is pumped to 2×10 -3 Pa, high-purity argon with a purity of 99.99% is filled into the furnace until the pressure in the furnace is -0.02 MPa. After standing for 10 s, the next gas washing is carried out, and this process is repeated 3 times.

6. The preparation method of the (FeCoNiCrMn)Si high-entropy silicide according to claim 2, characterized in that: During melting, the voltage used is 70 V, and the current is 100-150 A. When the material is completely melted, turn on the magnetic stirring function. The magnetic stirring current is 20 A, and the time is 1 min. Repeat melting 5 times to obtain the button ingot.

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