阅读说明：本技术 兼具高比强度、高塑性和高韧性的富Ti高熵合金及其制备 (Ti-rich high-entropy alloy with high specific strength, high plasticity and high toughness and preparation thereof ) 是由 朱正旺 曾帅 张海峰 张宏伟 付华萌 李宏 王爱民 张龙 李正坤 李伟 于 2021-07-22 设计创作，主要内容包括：本发明涉及一种兼具高比强度、高塑性和高韧性的富Ti高熵合金及其制备方法,所述高熵合金原子百分比表达式为Ti-(a)Zr-(b)Nb-(c)V-(d)Al-(e),其中42≤a≤46,21≤b≤23,13＜c≤16,13≤d≤15,0≤e≤10,且a/b＝2,a+b+c+d+e＝100。通过合金成分和制备工艺调控,获得了单一BCC相高熵合金。与传统金属材料相比,该合金具有高比强度、优异的拉伸塑性、高冲击韧性等特点,突破了传统金属材料或高熵合金难以兼具高强度、高塑性和高韧性的难题。所述富Ti高熵合金通过限定Ti、Zr成分比,具有相对较低的熔点,可以采用常规熔炼方法制备吨级以上合金锭,且易于成形,制备工艺简单,有利于实现工业化应用；含有Zr、Nb等元素,具有良好的耐腐蚀性能。在海洋、航空航天等领域具有广阔的应用前景。(The invention relates to a Ti-rich high-entropy alloy with high specific strength, high plasticity and high toughness and a preparation method thereof, wherein the high-entropy alloy has an atomic percentage expression of Ti a Zr b Nb c V d Al e Wherein a is more than or equal to 42 and less than or equal to 46, b is more than or equal to 21 and less than or equal to 23, c is more than 13 and less than or equal to 16, d is more than or equal to 13 and less than or equal to 15, e is more than or equal to 0 and less than or equal to 10, and a/b is 2, and a + b + c + d + e is 100. The single BCC phase high-entropy alloy is obtained by regulating and controlling alloy components and a preparation process. Compared with the traditional metal material, the alloy has the characteristics of high specific strength, excellent tensile plasticity, high impact toughness and the like, and breaks through the difficult problem that the traditional metal material or high-entropy alloy is difficult to have high strength, high plasticity and high toughness. The Ti-rich high-entropy alloy has relatively low melting point by limiting the composition ratio of Ti and Zr, and can be prepared by adopting a conventional smelting methodThe alloy ingot is more than ton grade, is easy to form, has simple preparation process and is beneficial to realizing industrial application; contains Zr, Nb and other elements and has excellent corrosion resistance. Has wide application prospect in the fields of ocean, aerospace and the like.)

1. A Ti-rich high-entropy alloy with high specific strength, high plasticity and high toughness is characterized in that: the high entropy isThe atomic percent expression of gold is Ti_aZr_bNb_cV_dAl_eAnd the components are as follows: a is more than or equal to 42 and less than or equal to 46, b is more than or equal to 21 and less than or equal to 23, c is more than 13 and less than or equal to 16, d is more than or equal to 13 and less than or equal to 15, e is more than or equal to 0 and less than or equal to 10, and a/b is 2, and a + b + c + d + e is 100.

2. A Ti-rich high entropy alloy as claimed in claim 1, wherein the Ti-rich high entropy alloy is Ti₄₆Zr₂₃Nb₁₆V₁₅Or Ti₄₄Zr₂₂Nb₁₄V₁₃Al₇。

3. A Ti-rich high entropy alloy as claimed in claim 1, wherein the Ti-rich high entropy alloy is Ti₄₄Zr₂₂Nb₁₅V₁₅Al₄。

4. A Ti-rich high entropy alloy as claimed in claim 1, wherein the Ti-rich high entropy alloy is Ti₄₂Zr₂₁Nb₁₄V₁₃Al₁₀。

5. A preparation method of the Ti-rich high-entropy alloy of claim 1 is characterized by comprising the following steps:

step 1) converting the atomic percentage into mass percentage according to the alloy components and weighing the ingredients;

step 2) cleaning and drying the weighed raw materials, then uniformly mixing the raw materials by a mixer, and finally compacting the uniformly mixed raw materials into blocks by a press machine to preliminarily obtain raw material blocks with relatively uniform components;

and 3) putting the raw material blocks into a crucible of a vacuum smelting furnace, uniformly melting the raw material blocks by adjusting process current, and performing turnover smelting for multiple times to obtain a master alloy ingot.

6. The preparation method of the Ti-rich high-entropy alloy as claimed in claim 5, characterized in that the melted mother alloy ingot is subjected to high-temperature solid solution, forging and heat treatment to obtain a target high-entropy alloy with uniform components and structures; wherein the high-temperature solid solution temperature is 1200-1350 ℃, and the heat preservation time is 3-5 h; the heat treatment temperature is 800-1200 ℃, and the heat preservation time is 1-4 h.

7. A preparation method of the Ti-rich high-entropy alloy according to claim 5 or 6, wherein in the step 1), the metal raw material is particles with industrial-grade purity, and the particle size range is 1-3 mm; the mixer is a three-dimensional 360-degree mixer, the mass ratio of raw materials to steel balls is 1: 1-3, and the diameter of the steel balls is 15-30 mm.

8. A preparation method of the Ti-rich high-entropy alloy according to claim 5 or 6, wherein the uniformly mixed raw materials are compacted by a press in the step 2), and the maximum bearing pressure of the raw material block is 500 MPa.

9. A preparation method of the Ti-rich high-entropy alloy according to claim 5 or 6, characterized in that in the step 3), a water-cooled copper crucible is adopted as a vacuum smelting furnace; the smelting current is 500-1000A, the time is 10-30 min, and the smelting is repeated for 7 times.

10. A method for preparing a Ti-rich high-entropy alloy according to claim 5 or 6, wherein in the step 2), the raw material blocks are combined together and made into a consumable electrode by vacuum plasma welding; in the step 3), the vacuum smelting furnace is a vacuum consumable electrode arc furnace, a water-cooled copper crucible is adopted, the smelting current is 20 kA-30 kA, the smelting voltage is 30-40V, and the turnover smelting is repeated for 7 times.

Technical Field

The invention belongs to the field of metal materials and preparation thereof, and particularly relates to a Ti-rich high-entropy alloy with high specific strength, high plasticity and high toughness and a preparation method thereof.

Background

Under the current 'carbon reduction' goal, the development of high-performance metal structural materials has become an urgent need. The research of traditional alloys, particularly structural application alloys, has relatively matured the technical research. Typically, such alloys contain a predominant chemical constituent of the base element, which is 80% (by weight) or more of the total composition. This limited range of alloying strategies stems primarily from the fact that ternary or higher order intermetallics are unexpectedly formed in the multi-component alloy after prolonged exposure to higher operating temperatures. The formation of these complex intermetallic compounds often severely deteriorates the mechanical properties, corrosion resistance and structural stability of the material, bringing about a great risk to its service. This strategy imposes a great limitation on designing metal materials with higher performance.

In the past decade, High Entropy Alloys (High Entropy Alloys) have gradually come into the field of view as a completely new concept of Alloys, having unique composition and structure, and thus having many very excellent properties, such as good thermal stability, High hardness and strength, excellent magnetic and electrical conductivity, impressive wear and corrosion resistance, and being able to meet the use requirements of extreme environments for materials. Senkov et al in 2010 proposed a high entropy alloy consisting of Nb, Ta, Mo, W and other refractory elements. The yield strength of both refractory high entropy alloys, NbMoTaW and VNbMoTaW, is reported to exceed 400MPa at 1600 ℃ and is much higher than 718 nickel-base superalloy at 1000 ℃ (below 200 MPa). This indicates that these alloys may replace nickel-based superalloys as the next generation of high temperature structural materials due to their attractive high temperature mechanical properties. Thereafter, the component elements of such high-entropy alloys are further expanded to nine (Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W). Single BCC structural alloys represented by ZrTiHfNbTa alloy and the like, nbcrmo0.5ta0.5tizr alloy composed of BCC phase + Laves phase, and almo0.5nbta0.5tizr alloy composed of BCC phase + B2 were reported in succession. Although these alloys have extremely high room temperature strength and even high temperature strength, the problems of room temperature brittleness, high density and the like generally exist, and the processing and application of the alloys are severely limited. In addition, the high-entropy alloy has multiple components, large physical property difference and complex components, and how to obtain uniform and consistent components and structures in the preparation, processing and metallurgy processes is of great importance to realizing high performance of the high-entropy alloy. Most of the existing researches are focused on the preparation of dozens of grams to thousands of grams of alloy materials. The technical level of preparation of the material is difficult to support the practical engineering application. The development of a preparation method of the large-size high-entropy alloy is also one of the difficulties in the field of the current high-entropy alloy.

Under the existing material science and engineering theory framework, the metal material is difficult to have high strength, high plasticity and high toughness at the same time. How to break through the contradiction between strong plasticity and toughness is a huge challenge in the field of material science and engineering. The design concept of the high-entropy alloy provides possibility for breaking through the contradiction. In conclusion, the research of the high-entropy alloy material with large size and excellent comprehensive performance through the design of alloy components and the regulation and control of a preparation method is an urgent need in the field of the current metal materials.

Disclosure of Invention

The present invention is directed to the above technologyIn the deficiency, Ti with low melting point is selected in the Ti-Zr phase diagram₂By referring to the design concept of the high-entropy alloy, Zr alloy introduces body-centered cubic (bcc) phase stable elements Nb and V, Al and other alloy elements with strong solid solution strengthening effect, develops a single bcc phase Ti-rich high-entropy alloy with low melting point, high specific strength, high plasticity and high toughness, and breaks through the difficult problem that the high-entropy alloy is 'strong plastic'/'strong toughness' and is difficult to combine. In the aspect of the preparation method, the preparation of the ton-level high-quality high-entropy alloy material is realized through the four-step cooperative control of the uniformity of components from raw materials to smelting, forging and heat treatment, and the problem that the high-quality large ingot of the high-entropy alloy is difficult to prepare at present is solved.

The technical scheme of the invention is as follows:

a Ti-rich high-entropy alloy with high specific strength, high plasticity and high toughness is characterized in that: the atomic percent expression of the high-entropy alloy is Ti_aZr_bNb_cV_dAl_eAnd the components are as follows: a is more than or equal to 42 and less than or equal to 46, b is more than or equal to 21 and less than or equal to 23, c is more than 13 and less than or equal to 16, d is more than or equal to 13 and less than or equal to 15, e is more than or equal to 0 and less than or equal to 10, and a/b is 2, and a + b + c + d + e is 100.

Preferably, the Ti-rich high-entropy alloy is Ti₄₆Zr₂₃Nb₁₆V₁₅，Ti₄₄Zr₂₂Nb₁₅V₁₅Al₄，Ti₄₄Zr₂₂Nb₁₄V₁₃Al₇，Ti₄₂Zr₂₁Nb₁₄V₁₃Al₁₀。

The density of the Ti-rich high-entropy alloy is 5.6-5.9 g/cm³And tensile plasticity (9% -23%), wherein the cast state Ti₄₂Zr₂₁Nb₁₄V₁₃Al₁₀The specific strength of the high-entropy alloy can reach 200MPa g^-1cm³Forged Ti₄₄Zr₂₂Nb₁₅V₁₅Al₄The impact toughness of the high-entropy alloy can reach 220J/cm²。

The preparation method of the Ti-rich high-entropy alloy specifically comprises the following steps:

step 1) converting the atomic percentage into mass percentage according to the alloy components and weighing the ingredients;

step 2) cleaning and drying the weighed raw materials, then uniformly mixing the raw materials by a mixer, and finally compacting the uniformly mixed raw materials into blocks by a press machine to preliminarily obtain raw material blocks with relatively uniform components;

step 3) putting the raw material blocks into a water-cooled crucible of a vacuum smelting furnace, uniformly melting the raw material blocks by adjusting process current, and performing turnover smelting for multiple times to obtain a master alloy ingot; the technological parameters are that the smelting current is 500-1000A, the time is 10-30 min, and the smelting is repeated for 7 times.

The application also provides a preparation method of the Ti-rich high-entropy alloy high-quality large ingot, which specifically comprises the following steps:

step 1) converting the atomic percentage into mass percentage according to the alloy components and weighing the ingredients;

step 2) cleaning and drying the weighed raw materials, then uniformly mixing the raw materials by a mixer, finally compacting the uniformly mixed raw materials into blocks by a press machine to preliminarily obtain raw material blocks with relatively uniform components, combining the raw material blocks together and manufacturing the consumable electrodes by vacuum plasma welding;

and 3) putting the raw material blocks into a vacuum consumable arc furnace, adopting a water-cooled copper crucible, carrying out turnover smelting for 7 times with the smelting current of 20-30 kA and the smelting voltage of 30-40V, and obtaining large-size mother alloy cast ingots.

Carrying out high-temperature solid solution, forging and heat treatment on the mother alloy ingot which is smelted by the two methods to obtain a target high-entropy alloy with uniform components and structures; wherein the high-temperature forging temperature is 1200-1350 ℃, and the heat preservation time is 3-5 h; the heat treatment temperature is 800-1200 ℃, and the heat preservation time is 1-4 h.

Wherein, in order to obtain a uniform chemical composition, the following measures are taken, such as:

firstly, the metal raw material is particles with industrial grade purity, and the particle size range is 1-3 mm; putting different metal raw materials into a three-dimensional 360-degree mixer according to nominal component requirements, and simultaneously putting steel balls with certain mass (the mass ratio of the raw materials to the steel balls is 1: 1-3, and the diameter is 15-30 mm) so as to obtain a uniform raw material mixture;

secondly, preventing the raw material mixture from being separated in the carrying or smelting process, putting the raw material mixture into a mould, compacting by using a press (100-500 MPa), and preparing a raw material compacted block with relatively uniform components;

thirdly, the integral melting of different alloy elements of the raw material compacted block is realized through process control during vacuum melting, so as to alloy, avoid the phenomena of component segregation, volatilization and the like caused by prior melting of low melting points in the traditional melting process, and realize the component homogenization of the material in the melting process through multiple times of turnover;

fourthly, the homogenization and the forging are combined, and finally, the high homogenization of the components and the structures of the materials is realized.

Compared with the prior art, the invention has the advantages that:

1. the invention is at low melting point Ti₂On the basis of the Zr alloy, elements such as Nb, V, Al and the like are introduced, so that on one hand, the Ti-rich high-entropy alloy with a single body-centered cubic structure is obtained, and on the other hand, the developed Ti-rich high-entropy alloy has a relatively low melting point, and is beneficial to alloy smelting and casting forming.

2. The Ti-rich high-entropy alloy has very excellent comprehensive performance, such as low density (< 6 g/cm)³) High specific strength (200 MPa g)^-1cm³) High room temperature tensile plasticity (9-23%) and high impact toughness (220J/cm)²) Is far superior to the similar alloys.

3. The Ti-rich high-entropy alloy contains Ti, Zr, Nb, V and Al elements, has a single bcc phase and uniform components, and has good corrosion resistance under various corrosion media.

4. The preparation method of the Ti-rich high-entropy alloy realizes the preparation of the large-size ton-grade high-entropy alloy material through reasonable raw material selection and multi-step component uniformity control measures, ensures the component and tissue uniformity of the material, and lays a solid foundation for the engineering application of the material.

5. The Ti-rich high-entropy alloy is suitable for various processing methods such as cold forming, hot forming, machining and the like, and has important application prospects in the fields of ocean, aerospace, high-end equipment manufacturing and the like.

Drawings

FIG. 1 shows as-cast Ti prepared₄₆Zr₂₃Nb₁₆V₁₅Microstructure of the high entropy alloy;

FIG. 2 shows as-cast Ti prepared₄₄Zr₂₂Nb₁₅V₁₅Al₄Microstructure of the high entropy alloy;

FIG. 3 shows as-cast Ti prepared₄₄Zr₂₂Nb₁₄V₁₃Al₇Microstructure of the high entropy alloy;

FIG. 4 shows as-cast Ti prepared₄₂Zr₂₁Nb₁₄V₁₃Al₁₀Microstructure of the high entropy alloy;

FIG. 5 is an XRD pattern of the as-cast Ti-rich high entropy alloy prepared;

FIG. 6 is a stress-strain curve of room temperature tensile of the as-cast Ti-rich high entropy alloy prepared;

FIG. 7 is a view of a forged Ti prepared₄₄Zr₂₂Nb₁₅V₁₅Al₄Microstructure of the high entropy alloy;

FIG. 8 is a forged Ti prepared₄₄Zr₂₂Nb₁₅V₁₅Al₄XRD pattern of high entropy alloy;

FIG. 9 is a forged Ti prepared₄₄Zr₂₂Nb₁₅V₁₅Al₄Room temperature tensile stress-strain curve of high entropy alloy;

FIG. 10 is a 1000kg grade Ti-rich high entropy alloy ingot prepared.

Detailed Description

The technical solution of the present invention is further described below with reference to specific embodiments.

Example 1

Ti with high specific strength, high plasticity and high toughness₄₆Zr₂₃Nb₁₆V₁₅The preparation method of the high-entropy alloy comprises the following specific steps:

step (1): according to the alloy components, the ingredients are weighed according to the atom percentage conversion of Ti, Zr, Nb and V, 34, 32, 23 and 11; the raw materials are all particles with industrial grade purity, the particle size range is 1-3 mm, the weighed raw material particles are cleaned and dried, the raw material particles are placed into a three-dimensional mixer, and meanwhile, steel balls with certain mass (the mass ratio of the raw materials to the steel balls is 1: 1-3, and the diameter of the steel balls is 15-30 mm) are placed, so that a uniform raw material mixture is obtained.

Step (2): compacting the obtained raw material mixture into blocks by a press machine, and primarily obtaining raw material blocks with relatively uniform components, wherein the maximum bearing pressure of the raw material blocks is 500 MPa.

And (3): putting the obtained raw material block into a crucible of a vacuum arc furnace for smelting, and vacuumizing until the vacuum degree is less than or equal to 3.5 x 10^-3Pa, smelting the raw material blocks, adjusting the smelting current (500A-1000A) to realize uniform melting of the raw material blocks, and performing turnover smelting for multiple times to obtain high-entropy alloy cast ingots with uniform components.

Referring to FIG. 1, it can be seen that the as-cast Ti of the examples of the present invention₄₆Zr₂₃Nb₁₆V₁₅The high-entropy alloy structure is a typical cast dendritic structure, but elements between dendrites and dendrites are not obvious, and the high-entropy alloy structure is more prone to a near-isometric crystal structure. As-cast Ti of the examples of the present invention can be seen by reference to the XRD pattern of FIG. 5₄₆Zr₂₃Nb₁₆V₁₅The refractory high entropy alloy has a single BCC crystal structure at room temperature. As can be seen from the room temperature tensile test results in Table 1 and FIG. 6, the alloy density is 5.878g/cm³The yield strength was 790MPa, and the elongation at break exceeded 20%.

Example 2

The difference from the embodiment 1 is that: the alloy component in this example is Ti₄₄Zr₂₂Nb₁₅V₁₅Al₄。

Referring to FIG. 2, it can be seen that the as-cast Ti of the examples of the present invention₄₄Zr₂₂Nb₁₅V₁₅Al₄The high-entropy alloy structure is a typical cast dendritic structure, but elements between dendrites and dendrites are not obvious, and the high-entropy alloy structure is more prone to a near-isometric crystal structure. Referring to the XRD pattern of FIG. 5, embodiments of the present invention can be seenAs-cast Ti₄₄Zr₂₂Nb₁₅V₁₅Al₄The high entropy alloy has a single BCC crystal structure at room temperature. As can be seen from the room temperature tensile test results in Table 1 and FIG. 6, the alloy density is 5.765g/cm³The yield strength was 897MPa, and the elongation at break exceeded 20%.

Example 3

The difference from the embodiment 1 is that: the alloy component in this example is Ti₄₄Zr₂₂Nb₁₄V₁₃Al₇。

Referring to FIG. 3, it can be seen that the as-cast Ti of the examples of the present invention₄₄Zr₂₂Nb₁₄V₁₃Al₇The high-entropy alloy structure is a typical cast dendritic structure, but elements between dendrites and dendrites are not obvious, and the high-entropy alloy structure is more prone to a near-isometric crystal structure. As-cast Ti of the examples of the present invention can be seen by reference to the XRD pattern of FIG. 5₄₄Zr₂₂Nb₁₄V₁₃Al₇The high entropy alloy has a single BCC crystal structure at room temperature. As can be seen from the room temperature tensile test results in Table 1 and FIG. 6, the alloy density is 5.674g/cm³The yield strength of the alloy is 1041MPa, and the elongation at break is kept between 10% and 18%.

Example 4

The difference from the embodiment 1 is that: the alloy component in this example is Ti₄₂Zr₂₁Nb₁₄V₁₃Al₁₀。

Referring to FIG. 4, it can be seen that the as-cast Ti of the examples of the present invention₄₂Zr₂₁Nb₁₄V₁₃Al₁₀The high-entropy alloy structure is a typical cast dendritic structure, but elements between dendrites and dendrites are not obvious, and the high-entropy alloy structure is more prone to a near-isometric crystal structure. As-cast Ti of the examples of the present invention can be seen by reference to the XRD pattern of FIG. 5₄₂Zr₂₁Nb₁₄V₁₃Al₁₀The high entropy alloy has a single BCC crystal structure at room temperature. As can be seen from the room temperature tensile test results in Table 1 and FIG. 6, the alloy density is 5.608g/cm³The yield strength is 1118MPa, and the alloy specific strength reaches 200MPa g^-1cm³And elongation at breakThe rate is also kept between 9 and 15 percent.

TABLE 1 Density, yield Strength and elongation of as-cast Ti-Rich high entropy alloys

Example 5

The difference from the embodiment 1 is that: the alloy has different components and different preparation methods.

The alloy component in this example is Ti₄₄Zr₂₂Nb₁₅V₁₅Al₄After the high-entropy alloy ingot is obtained by the smelting method, the high-entropy alloy ingot is subjected to high-temperature solid solution, forging and heat treatment to obtain the forged high-entropy alloy with uniform components and structures. Wherein the solid solution temperature is 1200-1350 ℃, and the heat preservation time is 3 h.

TABLE 2 cast and forged Ti₄₄Zr₂₂Nb₁₅V₁₅Al₄Impact toughness test result of high-entropy alloy

Referring to FIG. 7, it can be seen that forged Ti of the embodiment of the present invention₄₄Zr₂₂Nb₁₅V₁₅Al₄The high-entropy alloy structure is a typical equiaxial crystal structure, the grain size distribution is uniform, and the average grain size is 193 mu m. Referring to the XRD pattern of FIG. 8, it can be seen that forged Ti of the examples of the present invention₄₄Zr₂₂Nb₁₅V₁₅Al₄The high-entropy alloy has a single BCC crystal structure at room temperature, and the diffraction peak of XRD is sharp, which shows that the degree of crystallization is higher. As can be seen by referring to FIG. 9 and Table 2, forged Ti₄₄Zr₂₂Nb₁₅V₁₅Al₄The room-temperature tensile yield strength of the high-entropy alloy is 930MPa, the elongation at break is close to 25 percent, and the impact toughness reaches 220J/cm²Compared with the as-cast alloy, the alloy is improved by 188 percent.

Example 6

A preparation method of a 1000Kg grade Ti-rich high-entropy alloy comprises the following specific steps:

step (1): converting the atomic percentage into mass percentage according to the alloy components and weighing the ingredients; the raw materials are all particles with industrial grade purity, the particle size range is 1-3 mm, the total mass of the raw materials is 1024Kg, the weighed raw material particles are cleaned and dried, and are placed into a three-dimensional mixer, and meanwhile, steel balls with certain mass (the mass ratio of the raw materials to the steel balls is 1: 1-3, and the diameter of the steel balls is 15-30 mm) are placed, so that a uniform raw material mixture is obtained.

Step (2): compacting the obtained raw material mixture into blocks by a press machine, preliminarily obtaining raw material blocks with relatively uniform components, wherein the maximum bearing pressure of the raw material blocks is 500MPa, and then combining a plurality of raw material blocks together to prepare the consumable electrode.

And (3): and sequentially putting the obtained consumable electrodes into a vacuum consumable arc furnace, wherein the vacuum degree is less than or equal to 0.01Pa in the smelting process, uniformly melting the raw material blocks by adjusting the smelting current (20 kA-30 kA) and the smelting voltage (30-40V), and performing turnover smelting for 7 times to obtain the mother alloy ingot with the weight of 1024 Kg.

And (4): and carrying out high-temperature solid solution, forging and heat treatment on the smelted mother alloy ingot to obtain the target high-entropy alloy with uniform components and structures. Wherein the solid solution temperature is 1300-1350 ℃, and the heat preservation time is 5 h.

The 1000Kg grade Ti-rich high entropy alloy ingot obtained by consumable melting is shown in figure 10.

The invention is not the best known technology.

The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.