CN115449691A - Ultrahigh-strength-plasticity matched high-entropy alloy and preparation method thereof - Google Patents
Ultrahigh-strength-plasticity matched high-entropy alloy and preparation method thereof Download PDFInfo
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Abstract
The high-entropy alloy comprises main element elements and auxiliary element elements, wherein the main element elements comprise Ni, fe, co and Cr, the auxiliary element elements comprise Al, ti, W, mo and Nb, and different precipitates are introduced into the main element elements by adding the auxiliary element elements. The high-entropy alloy is treated by a specific heat treatment process, so that the grain size, the dislocation number and the morphology of a precipitation phase of the alloy can be excellently matched, the yield strength of the high-entropy alloy reaches more than 1700MPa, the tensile strength of the high-entropy alloy mostly reaches more than 2.0GPa, and the high-entropy alloy has good toughness and higher yield strength and meets the requirements of the mechanical properties of modern industrial materials.
Description
Technical Field
The application relates to the technical field of metal materials, in particular to an ultrahigh strength-plasticity matched high-entropy alloy and a preparation method thereof.
Background
The high-entropy alloy (HEA) has a large number of elements and high content of each alloy element, so that the mixing entropy of the alloy is large, the alloy elements tend to be disorderly arranged to form a simple Body Centered Cubic (BCC) or Face Centered Cubic (FCC) phase, and the novel alloy material has wide attention in the research field and has a wide application prospect due to excellent comprehensive properties such as high hardness, high strength, high temperature creep resistance, high temperature oxidation resistance, corrosion resistance, high resistivity, good electromagnetic property and the like.
In recent years, the strengthening of FCC-type FeCoCrNi-based high-entropy alloys (i.e., multi-principal-element high-entropy alloys formed by using four metals of iron, cobalt, chromium, and nickel as main elements, in which the matrix components are mainly iron, cobalt, chromium, and nickel, and the lattice type is a face-centered cubic FCC lattice) has been widely studied. The results show that the formation of precipitates is promoted by doping of the alloying elements and thermo-mechanical processing, which is very effective for strengthening such alloys. However, precipitates also tend to cause ductility degradation, which limits the alloy to achieving excellent tensile properties with the desired strength-ductility "tradeoff".
The most commonly used alloying element in high entropy alloys is aluminum (Al) or titanium (Ti). The addition of these elements generally results in the formation of geometrically close-packed phases (GCP phase, including γ '-Ni3Al phase, η -Ni3Ti phase, and α -Ni2AlTi phase, where γ' -Ni3Al phase is of the crystal lattice type LI2 (ordered body-centered cubic lattice) and has the chemical composition Ni3Al, η -Ni3Ti phase is of the crystal lattice type ordered close-packed hexagonal lattice and has the chemical composition Ni3Ti, and α -Ni2AlTi phase is of the crystal lattice type face-centered cubic structure and has the chemical composition Ni2 AlTi). The crystal lattice of these phases is in accordance with the matrix phase. Studies by zhaoning Lu et al show that low lattice mismatch lowers the nucleation barrier of the precipitated phase, allowing the creation and stabilization of a nano-precipitated phase. By optimizing the Al and Ti concentrations, nanoscale coherent LI 2-gamma 'phase (gamma' -LI2-Ni3Al phase, the lattice type of which is LI2 (ordered body-centered cubic lattice), chemical components of which are Ni3Al and are a precipitation phase and distributed in the matrix of the alloy) particles are precipitated in the CoCrFeNi-based high-entropy alloy. The fine coherent precipitated phases contribute to the enhanced strength-ductility synergy. For example, LI2 type nanoparticle-reinforced (FeCoNi) 86-Al7Ti7 HEA (i.e., a high entropy alloy that is reinforced by a γ' -LI2-Ni3Al phase, whose crystal lattice is coherent with the matrix, is coherent-reinforced, not only increasing the strength, but also not adversely affecting the plasticity) can reach a yield strength of about 1.0GPa, and has a ductility of about 50%. The formation of LI2- γ 'nanoprecipitates provides an outstanding contribution to the strengthening of the high entropy alloy, resulting in a high strength and ductility combination with Ti playing a key role in the precipitation of the γ' phase (i.e. the γ '-LI2-Ni3Al phase), while Al improves the stability of the γ' phase.
Recently, some small atomic radius alloying elements, represented by molybdenum (Mo), have been used to strengthen HEA. The addition of Mo can produce different types of topologically closely packed phases (TCP phases, including σ -phase, μ -phase, and Laves phases, etc.) depending on their doping content and heat treatment parameters. Unlike nickel-based superalloys, these phases in FCC-HEA are effective in strengthening the alloy without creating severe brittleness. This is because solid solution FCC matrix phases generally exhibit very high plasticity and retain some toughness after precipitation strengthening. The results show that the sigma and mu phases precipitated in CoCrFeNiMo0.3 HEA by thermomechanical working effectively strengthen the alloy, resulting in a good combination of tensile strength of 1.2GPa and elongation of 19%. In addition to Mo, HEA can be strengthened by adding elements such as niobium (Nb), manganese (Mn), and vanadium (V) to create TCP precipitate phases. Interestingly, the addition of Nb can form TCP in HEA, while promoting the formation of geometrically close-packed phases of γ', and ε. However, nb does not sufficiently exert its effect in reinforcing the strength-ductility synergistic effect. Generally, the tensile yield strength is lower than 1000MPa, and the elongation is higher (15-55%).
In order to effectively strengthen FeCoCrNi HEA (namely the Fe-Cr-Co-Ni-based high-entropy alloy), the structure design has important significance. A strategy for optimizing precipitation and introducing a non-uniform microstructure by thermomechanical processing is proposed. The eutectic AlCoCrFeNi2.1 alloy with the non-uniform structure can achieve the tensile yield strength of about 1800MPa and the elongation of about 5 percent through low-temperature rolling and warm-rolling treatment. This strength enhancement relies on dislocation strengthening and precipitation strengthening and exhibits an unprecedented strength-plastic match.
Although the above tensile properties have a good strength-plastic match, their low elongation, negative strain hardening rate and difficulty in mass production limit make it difficult to apply to practical industrial structural materials.
However, the heterogeneous microstructure may produce a synergistic strengthening effect, which follows:
σ 0.2 ＝σ 1 +Δσ G +Δσ S +Δσ P +Δσ D (1)
wherein σ 0.2 is the enhanced yield strength; σ 1 is the original yield strength; Δ σ S, Δ σ G, Δ σ D, and Δ σ P represent solid solution strengthening, grain boundary hardening, dislocation strengthening, and precipitation strengthening, respectively. After the thermal mechanical processing, the high-entropy alloy can obtain a non-uniform microstructure and shows excellent strengthening effect.
Therefore, obtaining a CoCrFeNi-based high entropy alloy with an excellent combination of strength and ductility remains a challenge in the research field. In practice, it is of great importance that the prepared high-entropy alloy has sufficiently high strength, ductility and strain hardening rate.
Disclosure of Invention
The application aims to provide the ultrahigh-strength-plasticity matched high-entropy alloy and the preparation method thereof, so that the high-entropy alloy can keep high elongation and positive hardening rate while the strength is greatly improved, the requirement of modern industry on the mechanical property of the material is met, and the problems that the existing high-entropy alloy is insufficient in strength, poor in plasticity, poor in strength-plasticity matching and difficult to produce in large batch are solved.
The embodiment of the application can be realized by the following technical scheme:
an ultrahigh strength-plastic matching high entropy alloy comprises principal element elements and secondary element elements, wherein the principal element elements comprise Ni, fe, co and Cr, the secondary element elements comprise Al, ti, W, mo and Nb, and the secondary element elements are added,
so that the principal element introduces a different precipitate.
Further, the atomic percentage content of each element in the principal element and the accessory element is,
a principal element, ni 22at.% to 25% wt.%, fe 13at.% to 16at.%, co 32.5at.% to 35.5at.%, cr 12at.% to 15at.%;
the secondary element comprises 3.0at.% to 5.0at.% of Al, 1.5at.% to 3.5at.% of Ti, 0.5at.% to 2.0at.% of W, 1.0at.% to 2.5at.% of Mo, and 0.25at.% to 1.25at.% of Nb.
A preparation method of the ultrahigh-strength-plastic-matched high-entropy alloy comprises the following steps:
firstly, alloy smelting: the method comprises the following steps of taking metal simple substances Ni, fe, co, cr, al, ti, W, mo and Nb as raw materials, designing component proportion according to the atomic percentage content of each element of the high-entropy alloy to obtain pure metal with the purity of more than 99.95wt.%, putting the pure metal into an induction smelting furnace to be smelted to obtain multi-main-element alloy melt, and then casting the multi-main-element alloy melt into a mold to form ingot casting blanks;
step two, homogenization treatment: homogenizing the ingot blank in a vacuum heat treatment furnace at 1200 ℃ for 24 hours, and then taking out the ingot blank for air cooling to obtain a first alloy body;
thirdly, forging and forming: heating the first alloy body to 1200 ℃, and then carrying out hot forging to obtain a second alloy body with a specified size by hot forging the first alloy body;
step four, solution treatment: putting the second alloy body into a vacuum furnace at 1200 ℃ for heat preservation for 2 hours, and then performing water quenching to obtain a third alloy body;
step five, cold rolling treatment: rolling the third alloy body at room temperature by 75% -90% of rolling reduction in multiple passes, and rolling the third alloy body into a fourth alloy body with specified size;
sixthly, annealing treatment: preserving the heat of the fourth alloy body at the temperature of 750-900 ℃ for 30 minutes, and then performing water quenching to obtain a fifth alloy body;
step seven, aging treatment: and (3) preserving the heat of the fifth alloy body for 48 hours at the temperature of 500-600 ℃, and then performing air cooling to obtain a high-entropy alloy finished product.
Further, the ingot blank includes an ingot rod body blank and an ingot plate body blank, and the ingot plate body blank is a blank obtained by cutting the ingot rod body blank.
Further, the size of the transverse cutting area of the ingot bar body blank is
The cross-sectional area of the ingot plate blank has a dimension of
Further, the fourth alloy body is subjected to heat preservation for 30 minutes at 800 ℃ or 825 ℃ or 850 ℃ and then is subjected to water quenching, so that a fifth alloy body is obtained.
The ultrahigh strength-plasticity matched high-entropy alloy and the preparation method thereof provided by the embodiment of the application have the following beneficial effects:
according to the method, different precipitates are introduced to obtain a multi-main-element alloy product through the addition of auxiliary elements W, mo, al, ti and Nb, and after the multi-main-element alloy product is subjected to forging, rolling, annealing and aging process treatment, the high-entropy alloy presents a heterogeneous microstructure, so that the precipitation strengthening of the high-entropy alloy is greatly improved, and meanwhile, ultrafine recrystallized grains are generated and a certain number of dislocations are reserved, so that the strength of the high-entropy alloy is greatly improved, and meanwhile, the high elongation and the positive hardening rate are also kept;
the high-entropy alloy prepared by the method can be used for preparing plates and bars with certain volumes, changes the condition that the traditional ultrahigh-strength high-entropy alloy can only be used for preparing high-entropy alloy button cast ingots with extremely small sizes by using an electric arc melting furnace, can be applied to the preparation of high-strength bolts and plates in the aviation industry and has excellent forming performance;
through the heat treatment process, particularly the sixth annealing treatment and the seventh aging treatment, the grain size of the alloy is extremely fine, a certain amount of dislocation is reserved to cause work hardening, and the strength of the alloy is ensured to a certain extent. In addition, the precipitation phase of the alloy under the process can be controlled to be in a nanometer level, and the rapid reduction of plasticity is not generated while the alloy is strengthened, so that the grain size, the dislocation number and the morphology of the precipitation phase of the alloy can be excellently matched by using the heat treatment process, and the excellent strength-plasticity matching alloy can be generated. The optimal strength plasticity-matching of the obtained high-entropy alloy can reach rare yield strength of 2.2GPa and the elongation of more than 10 percent, and the high-entropy alloy with different strength-plasticity matching can be obtained by adjusting the heat treatment process, thereby showing wide application prospect.
Drawings
FIG. 1 is a scanning electron microscope image and an electron backscatter diffraction analysis chart of samples prepared in example 1, example 8 and example 9 of the present application;
fig. 2 to 4 are tensile engineering stress-strain curves of the high-entropy alloys prepared in example 1, example 8 and example 9.
Detailed Description
Hereinafter, the present application will be further described based on preferred embodiments with reference to the drawings.
In addition, for convenience of understanding, various components on the drawings are enlarged (thick) or reduced (thin), but this is not intended to limit the scope of the present application.
Singular references also include plural references and vice versa.
In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "inner", "outer", etc. are used for indicating the orientation or positional relationship based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship which is usually arranged when the products of the embodiments of the present application are used, the description is only for convenience and simplicity, but the indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation and be operated, and thus, the application cannot be construed as being limited. Moreover, the terms first, second, etc. may be used in the description to distinguish between different elements, but these should not be limited by the order of manufacture or by importance to be understood as indicating or implying any particular importance, and their names may differ from their names in the detailed description of the application and the claims.
The terminology used in the description is for the purpose of describing the embodiments of the application and is not intended to be limiting of the application. It is also to be understood that, unless otherwise expressly stated or limited, the terms "disposed," "connected," and "connected" are intended to be open-ended, i.e., may be fixedly connected, detachably connected, or integrally connected; they may be mechanically coupled, directly coupled, indirectly coupled through intervening media, or may be interconnected between two elements. The specific meaning of the above terms in the present application will be specifically understood by those skilled in the art.
An ultrahigh strength-plastic matching high entropy alloy comprises main element elements and auxiliary element elements, wherein the main element elements comprise Ni, fe, co and Cr, the auxiliary element elements comprise Al, ti, W, mo and Nb, and different precipitates are introduced into the main element elements by adding the auxiliary element elements.
The high-entropy alloy comprises the following elements in percentage by atom:
a principal element, ni 22at.% to 25%;
the secondary element comprises 3.0-5.0 at.% of Al, 1.5-3.5 at.% of Ti, 0.5-2.0 at.% of W, 1.0-2.5 at.% of Mo and 0.25-1.25 at.% of Nb;
wherein, the single impurity element in the impurity is less than or equal to 0.05at.%, and the total amount of all impurity elements is less than or equal to 0.15at.%.
Preferably, the purity of each elemental metal is 99.95wt.% or more.
The addition of W, mo, al, ti and Nb in the accessory element is to introduce different precipitates to obtain a multi-main element alloy product for further playing the role of precipitation strengthening, and then after the multi-main element alloy product is subjected to forging, rolling, annealing and aging process treatment, the high-entropy alloy presents a heterogeneous microstructure, so that the precipitation strengthening of the high-entropy alloy is greatly improved, and meanwhile, ultrafine recrystallized grains are generated and a certain number of dislocations are reserved, so that the strength of the high-entropy alloy is greatly improved, and meanwhile, the high elongation and the positive hardening rate are also kept.
A preparation method of an ultrahigh strength-plasticity matched high-entropy alloy comprises the following steps:
firstly, alloy smelting: the method comprises the following steps of taking metal simple substances Ni, fe, co, cr, al, ti, W, mo and Nb as raw materials, designing component proportion according to the atomic percentage content of each element of the high-entropy alloy to obtain pure metal with the purity of more than 99.95wt.%, putting the pure metal into an induction smelting furnace to be smelted to obtain multi-main-element alloy melt, and then casting the multi-main-element alloy melt into a mold to form ingot casting blanks;
step two, homogenizing treatment: homogenizing the ingot blank in a vacuum heat treatment furnace at 1200 ℃ for 24 hours, and then taking out the ingot blank for air cooling to obtain a first alloy body;
thirdly, forging and forming: heating the first alloy body to 1200 ℃, and then carrying out hot forging to obtain a second alloy body with a specified size by hot forging the first alloy body;
step four, solution treatment: putting the second alloy body into a vacuum furnace at 1200 ℃, preserving heat for 2 hours, and then performing water quenching to obtain a third alloy body;
step five, cold rolling treatment: rolling the third alloy body by 75% -90% of rolling reduction in multiple passes at room temperature to obtain a fourth alloy body with specified size;
generally, the total rolling reduction rate of the cold rolling treatment is 60-90%, and the fourth alloy obtained after rolling by 75-90% of rolling reduction has uniform structure, superior surface quality and more excellent mechanical property and process property through repeated tests.
Sixthly, annealing treatment: the fourth alloy body is subjected to water quenching after being subjected to heat preservation for 30 minutes at the temperature of 750-900 ℃, so that a fifth alloy body is obtained, and is used for recrystallization of a cold-rolled deformation structure of the alloy through high-temperature annealing, so that the plasticity of the alloy is improved, the strength is slightly reduced, and the heat preservation time is shorter for 30 minutes because the reason that grains are prevented from excessively growing is that the fine grain strengthening is not facilitated, and the fine grain strengthening has positive effects on the strength and the plasticity;
step seven, aging treatment: and (3) keeping the temperature of the fifth alloy body at 500-600 ℃ for 48 hours, and then carrying out air cooling to obtain a high-entropy alloy finished product, wherein the meaning of long-time aging at low temperature is to slowly precipitate a precipitation phase of the alloy at low temperature and also to generate a large amount of fine second-phase precipitates, so that the strength of the alloy is further improved, and the severe reduction of plasticity is not generated.
Further, in the first step of the preparation method, the ingot blank comprises an ingot rod blank and an ingot plate blank, wherein the ingot plate blank is obtained by cutting the ingot rod blank by a linear cutting method.
In some preferred embodiments, the ingot rod charge cross-sectional area is sized to be
The cross-sectional area of the ingot plate blank has a dimension of
Accordingly, in the second step of the above preparation method, the first alloy body comprises a first alloy rod body and a first alloy plate body, wherein the first alloy rod body and the first alloy plate body are respectively alloy bodies obtained by homogenizing the ingot rod body blank and the ingot plate body blank.
Accordingly, in the third step of the above production method, the second alloy body includes a second alloy rod body and a second alloy plate body, and the second alloy rod body and the second alloy plate body are respectively an alloy body obtained by forging and forming the first alloy rod body and the first alloy plate body.
In some preferred embodiments, after the hot forging in the third step, the second alloy plate body is a short rod with a diameter of 60mm, and the second alloy plate body is a square plate with a thickness of 15 mm.
Correspondingly, in the fourth step of the preparation method, the third alloy body comprises a third alloy Jin Bangti and a third alloy plate body, and the third alloy Jin Bangti and the third alloy plate body are respectively alloy bodies obtained by solution treatment of the second alloy rod body and the second alloy plate body.
Correspondingly, in the fifth step of the preparation method, the fourth alloy body comprises a fourth alloy rod body and a fourth alloy plate body, and the fourth alloy rod body and the fourth alloy plate body are alloy bodies obtained by cold rolling treatment of a third alloy Jin Bangti and a third alloy plate body respectively.
In some preferred embodiments, after rolling in said fifth step, the diameter of the fourth alloy rod body is 19mm and the thickness of the fourth alloy plate body is 1.5mm.
Correspondingly, in the sixth step of the preparation method, the fifth alloy body comprises a fifth alloy Jin Bangti and a fifth alloy plate body, and the fifth alloy Jin Bangti and the fifth alloy plate body are respectively obtained by annealing the fourth alloy rod body and the fourth alloy plate body.
Correspondingly, in the seventh step of the preparation method, the high-entropy alloy finished product comprises a high-entropy alloy rod finished product and a high-entropy alloy plate finished product, and the high-entropy alloy rod finished product and the high-entropy alloy plate finished product are finished products obtained by aging treatment of the fifth alloy Jin Bangti and the fifth alloy plate respectively.
Through the heat treatment process of the specific process, the grain size of the alloy is extremely fine, a certain volume fraction of deformed structure is reserved, certain work hardening is reserved, and the strength of the alloy is guaranteed to a certain extent. The alloy is aged for a long time at low temperature, so that the precipitation phase can be controlled to be in a nanometer level, the alloy is strengthened without plasticity reduction, and the grain size, the dislocation number and the precipitation phase morphology of the alloy can be perfectly matched by using a specific heat treatment process, so that the high-entropy alloy with excellent strength-plasticity matching is produced. The meaning of the heat treatment is to achieve a good match of the grain size, dislocation density, recrystallization percentage and morphology of the precipitated phase in the alloy structure, thereby producing excellent strength plastic matching performance.
Example 1
Firstly, alloy smelting: taking metal simple substances Ni, fe, co, cr, al, ti, W, mo and Nb as raw materials, and mixing the raw materials according to the weight ratio of Co: cr: fe: ni: w: mo: al: ti: nb =34.25%:15%:15%:24%:1.5%:1.5%:5%:3%:0.75 percent of the weight percentage, accurately weighing 20kg of mixed raw materials, putting the mixed raw materials into an induction smelting furnace, and casting the mixed raw materials after smelting to obtain the cross-sectional area with the size of
Cutting the ingot rod blank into the cross-sectional area size of
The ingot plate blank of (1);
step two, homogenization treatment: carrying out homogenization treatment on the ingot plate blank in a vacuum heat treatment furnace at 1200 ℃ for 24 hours, and then taking out for air cooling to obtain a first alloy plate body;
thirdly, forging and forming: heating a first alloy plate body to 1200 ℃, and then performing hot forging to forge the first alloy plate body into a second alloy plate body with the thickness of 15 mm;
step four, solution treatment: putting the second alloy plate body into a vacuum furnace at 1200 ℃ for heat preservation for 2h, and then performing water quenching to obtain a third alloy plate body;
step five, cold rolling treatment: rolling the third alloy plate body by 90% of rolling reduction in multiple passes at room temperature until a fourth alloy plate body with the thickness of 1.5mm is obtained;
sixthly, annealing treatment: preserving the heat of the fourth alloy plate body at 800 ℃ for 30 minutes, and then performing water quenching to obtain a fifth alloy plate body;
step seven, aging treatment: and (3) preserving the heat of the fifth alloy plate body at 500 ℃ for 48 hours, and then carrying out air cooling to obtain a high-entropy alloy plate body finished product, which is marked as high-entropy alloy 1.
Examples 2 to 6:
only the atomic percentages of Ni, fe, co, cr, al, ti, W, mo and Nb are changed on the basis of the embodiment 1,
other steps and conditions are the same as those of the embodiment 1, and high-entropy alloys 2-6 are respectively prepared; wherein, the atomic percentages of Ni, fe, co, cr, al, ti, W, mo and Nb are detailed in Table 1:
TABLE 1
Examples 7 to 10
On the basis of example 1, the high-entropy alloy 7, the high-entropy alloy 8, the high-entropy alloy 9 and the high-entropy alloy 10 are respectively prepared by the steps and conditions the same as example 1 except that the heat preservation temperature in the sixth step is changed without changing the atomic percentages of Ni, fe, co, cr, al, ti, W, mo and Nb, and the fourth alloy plate body obtained by the fifth step is subjected to heat preservation at 750 ℃, 825 ℃, 850 ℃ and 900 ℃ for 30 minutes and then subjected to water quenching.
Example 11
On the basis of example 1, the high-entropy alloy 11 was prepared by performing rolling of 75% reduction in multiple passes on the third alloy sheet obtained by the fourth step at room temperature, without changing the atomic percentages of Ni, fe, co, cr, al, ti, W, mo, and Nb, but only changing the cold rolling reduction in the fifth step, and by the same steps and conditions as in example 1.
Example 12
On the basis of the example 1, the high-entropy alloy 12 is prepared by keeping the fifth alloy plate obtained by the sixth step at 600 ℃ for 48 hours and then cooling the fifth alloy plate by air, without changing the atomic percentages of Ni, fe, co, cr, al, ti, W, mo and Nb, and with the same conditions as the example 1.
The room temperature quasi-static tensile mechanical property tests of the high-entropy alloys 1 to 12 prepared in the above examples are respectively carried out, and the results are detailed in table 2.
TABLE 2
Analysis table 2 shows that the yield strength of the high-entropy alloy in each example of the application reaches 1700MPa or more, and the tensile strength of the high-entropy alloy mostly reaches 2.0GPa or more, and comparison analysis examples 1 and 7-10 shows that the cold-rolled deformation structure of the alloy can be recrystallized through high-temperature annealing, so that the plasticity of the alloy is improved, and the strength is slightly reduced; comparative analysis of examples 1 and 12 shows that the strength of the alloy is further improved at low temperature without a drastic reduction in plasticity when the alloy is aged at low temperature for a long time; comparative analysis of examples 1 and 11 shows that the larger the pressing amount is, the more uniform the structure and the more excellent the surface quality of the fourth alloy obtained after rolling, and the higher the strength of the high-entropy alloy is, the lower the shape is.
In order to more intuitively show the fact that after the auxiliary elements, namely W, mo, al, ti and Nb are added into the main elements to obtain a multi-main-element alloy product, and then the multi-main-element alloy product is subjected to forging, rolling, annealing and aging process treatment, the obtained high-entropy alloy not only has greatly improved strength, but also maintains high elongation and positive hardening rate, the following description is further provided in combination with FIGS. 1 to 4:
fig. 1 is a scanning electron microscope picture and an electron backscatter diffraction analysis picture of samples prepared in example 1, example 8 and example 9 of the present application, wherein (a), (b) and (c) represent the high-entropy alloy 1 in example 1, the high-entropy alloy 8 in example 8 and the high-entropy alloy 9 in example 9, respectively, and as shown in fig. 1, after 90% rolling, annealing and aging, phase particles (indicated by yellow arrows) rich in (Ti, nb) are observed in a Scanning Electron Microscope (SEM) picture and arranged along the rolling direction, and no cracks are found around.
After the annealing aging treatment, the shear band recrystallized and the sigma phase precipitated in submicron size (indicated by red arrows). In this case, shear bands were still observed under SEM.
Recrystallized grains were well observed in the EBSD-IPF pattern (electron back-scattered-inverse) after the annealing aging treatment. The KAM diagram (Kernel Average Misorientation) shows that the dislocation strain in the recrystallized region is reduced and the recrystallized area is small. Under SEM observation, as the annealing temperature increased, the recrystallized region expanded and the shear band disappeared, while the number of submicron sigma phase particles was the largest produced by annealing at 825 c and decreased after increasing to 850 c. Annealing at high temperature, the EBSD plot clearly shows recrystallized grains with very high index of separation due to more complete recrystallization. The KAM plot shows a further reduction in dislocation strain, indicating that the alloy recrystallizes more fully after annealing at higher temperatures.
Fig. 2 to 4 are tensile engineering stress-strain curves of the high-entropy alloys prepared in examples 1, 8 and 9, wherein the ordinate is stress and the abscissa is strain, and as shown in fig. 2 to 4, the yield strengths of the high-entropy alloys in examples 1, 8 and 9 of the present application are all 1700MPa or more, the tensile strengths are 2.0GPa or more, and the strengths are high. With respect to plasticity, after the alloy is subjected to thermo-mechanical treatment, a certain plasticity is still retained, which can meet a certain engineering application.
Comparing the three stress-strain curves, it can be seen that the high-entropy alloy 1 subjected to the heat preservation at 800 ℃ for 30 minutes, water quenching and air cooling aging treatment after the heat preservation at 500 ℃ for 48 hours has the highest strength, the tensile strength of the high-entropy alloy is 2606MPa, the yield strength of the high-entropy alloy is 2486MPa, and the plasticity of the high-entropy alloy is 3.5 percent.
The high-entropy alloy with the best plasticity is the high-entropy alloy 9 subjected to water quenching after being kept at 850 ℃ for 30 minutes, and the elongation is 17.9 percent, but the yield strength is only 1138MPa. The alloy with better strong plastic bonding is high-entropy alloy 8 which is water quenched after being kept at 825 ℃ for 30 minutes, the yield strength of the alloy is 2221MPa, and the elongation of the alloy is 11.2 percent.
While the present invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof as defined in the appended claims.
Claims (6)
1. An ultra-high strength-plastic matched high entropy alloy, characterized by:
the high-entropy alloy comprises principal element elements and auxiliary element elements, wherein the principal element elements comprise Ni, fe, co and Cr, the auxiliary element elements comprise Al, ti, W, mo and Nb, and different precipitates are introduced into the principal element elements by adding the auxiliary element elements.
2. An ultra-high strength-plastic matched high entropy alloy as claimed in claim 1, wherein:
the atomic percentage content of each element in the main element and the auxiliary element is as follows,
a principal element, ni 22at.% to 25% wt.%, fe 13at.% to 16at.%, co 32.5at.% to 35.5at.%, cr 12at.% to 15at.%;
the secondary element comprises 3.0at.% to 5.0at.% of Al, 1.5at.% to 3.5at.% of Ti, 0.5at.% to 2.0at.% of W, 1.0at.% to 2.5at.% of Mo1.0at.% of Nb, and 0.25at.% to 1.25at.% of Nb.
3. A method of producing an ultra-high strength-plastic matched high entropy alloy according to claim 1 or 2, comprising the steps of:
firstly, alloy smelting: the method comprises the following steps of taking metal simple substances Ni, fe, co, cr, al, ti, W, mo and Nb as raw materials, designing component proportion according to the atomic percentage content of each element of the high-entropy alloy to obtain pure metal with the purity of more than 99.95wt.%, putting the pure metal into an induction smelting furnace to be smelted to obtain multi-main-element alloy melt, and then casting the multi-main-element alloy melt into a mold to form ingot casting blanks;
step two, homogenizing treatment: homogenizing the ingot blank in a vacuum heat treatment furnace at 1200 ℃ for 24 hours, and then taking out the ingot blank for air cooling to obtain a first alloy body;
thirdly, forging and forming: heating the first alloy body to 1200 ℃, and then carrying out hot forging to obtain a second alloy body with a specified size by hot forging the first alloy body;
step four, solution treatment: putting the second alloy body into a vacuum furnace at 1200 ℃ for heat preservation for 2 hours, and then performing water quenching to obtain a third alloy body;
step five, cold rolling treatment: rolling the third alloy body by 75% -90% of rolling reduction in multiple passes at room temperature to obtain a fourth alloy body with specified size;
sixthly, annealing treatment: preserving the heat of the fourth alloy body at the temperature of 750-900 ℃ for 30 minutes, and then performing water quenching to obtain a fifth alloy body;
step seven, aging treatment: and (3) preserving the heat of the fifth alloy body for 48 hours at the temperature of 500-600 ℃, and then performing air cooling to obtain a high-entropy alloy finished product.
4. The method for preparing the ultrahigh strength-plastic matched high entropy alloy according to claim 3, wherein:
the ingot casting blank comprises an ingot casting rod body blank and an ingot casting plate body blank, wherein the ingot casting plate body blank is obtained by cutting the ingot casting rod body blank.
5. A method of producing an ultra-high strength-plastic matched high entropy alloy, according to claim 4, wherein:
the size of the transverse cutting area of the ingot bar body blank is
The cross-sectional area of the ingot plate blank has a dimension of
6. A method of producing an ultra-high strength-plastic matched high entropy alloy, according to claim 3, wherein:
and (3) preserving the heat of the fourth alloy body at 800 ℃ or 825 ℃ or 850 ℃ for 30 minutes, and then performing water quenching to obtain a fifth alloy body.
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| CN115852276A (en) * | 2022-12-23 | 2023-03-28 | 中国科学院金属研究所 | Grain boundary regulation and control process for inhibiting precipitation of harmful grain boundary precipitated phase in face-centered cubic high-entropy alloy |
| CN116162875A (en) * | 2023-03-14 | 2023-05-26 | 西安交通大学 | Heat treatment method for preparing high-entropy alloy with non-uniformity of components and prepared high-entropy alloy |
| CN116351994A (en) * | 2023-05-25 | 2023-06-30 | 北京中辰至刚科技有限公司 | Isothermal forging method of refractory high-entropy alloy product and processed product thereof |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115852276A (en) * | 2022-12-23 | 2023-03-28 | 中国科学院金属研究所 | Grain boundary regulation and control process for inhibiting precipitation of harmful grain boundary precipitated phase in face-centered cubic high-entropy alloy |
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| CN116162875A (en) * | 2023-03-14 | 2023-05-26 | 西安交通大学 | Heat treatment method for preparing high-entropy alloy with non-uniformity of components and prepared high-entropy alloy |
| CN116351994A (en) * | 2023-05-25 | 2023-06-30 | 北京中辰至刚科技有限公司 | Isothermal forging method of refractory high-entropy alloy product and processed product thereof |
| CN116351994B (en) * | 2023-05-25 | 2023-12-19 | 北京中辰至刚科技有限公司 | Isothermal forging method of refractory high-entropy alloy product and processed product thereof |
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