阅读说明：本技术 一种多尺度结构合金材料、制备方法及其用途 (Multi-scale structure alloy material, preparation method and application thereof ) 是由 康利梅 庞兴 于 2020-03-24 设计创作，主要内容包括：本发明涉及一种多尺度结构合金材料、制备方法及其用途,制备方法包括以下步骤：1)粉末致密化烧结：将合金粉末装入烧结模具,经预压后进行烧结,烧结压力为20～100MPa,烧结温度Ts满足：合金粉末相变峰的开始温度≤Ts≤合金粉末相变峰的结束温度；2)加高压处理：烧结结束后,加压冷却,冷却压力为10～500MPa；卸压冷却：待加压冷却温度降至550～600℃,迅速泄压,冷却得到合金材料。基于本发明的方法,开发了一种简便易操作的材料成形制备方法,将合金材料的制备及后续处理技术合二为一,实现双尺度/多尺度纳米/超细晶结构合金材料的一体化成形,通过原位调控合金内部的微观组织结构形态、晶粒尺度等,制备出高强韧的合金材料。(The invention relates to a multi-scale structure alloy material, a preparation method and application thereof, wherein the preparation method comprises the following steps: 1) powder densification and sintering: the alloy powder is filled into a sintering die, and sintering is carried out after prepressing, wherein the sintering pressure is 20-100 MPa, and the sintering temperature Ts satisfies the following requirements: the starting temperature of the phase transition peak of the alloy powder is less than or equal to Ts and less than or equal to the ending temperature of the phase transition peak of the alloy powder; 2) high-pressure treatment: after sintering, pressurizing and cooling, wherein the cooling pressure is 10-500 MPa; pressure relief and cooling: and when the pressure cooling temperature is reduced to 550-600 ℃, rapidly relieving the pressure, and cooling to obtain the alloy material. Based on the method, the invention develops a simple and easy-to-operate material forming preparation method, combines the preparation of the alloy material and the subsequent treatment technology into a whole, realizes the integrated forming of the alloy material with the double-scale/multi-scale nano/superfine crystal structure, and prepares the high-toughness alloy material by regulating and controlling the microstructure structure form, the grain size and the like in the alloy in situ.)

1. The preparation method of the multi-scale structural alloy material is characterized by comprising the following steps of:

1) powder densification and sintering: the alloy powder is filled into a sintering die, and sintering is carried out after prepressing, wherein the sintering pressure is 20-100 MPa, and the sintering temperature Ts satisfies the following requirements: the starting temperature of the phase transition peak of the alloy powder is less than or equal to Ts and less than or equal to the ending temperature of the phase transition peak of the alloy powder;

2) high-pressure treatment: after sintering, pressurizing and cooling, wherein the cooling pressure is 10-500 MPa;

3) pressure relief and cooling: and when the pressure cooling temperature is reduced to 550-600 ℃, rapidly relieving the pressure, and cooling to obtain the alloy material.

2. The method for preparing the multi-scale structural alloy material according to claim 1, wherein the alloy powder is prepared by any one of an atomization method, a high-energy ball milling method, an electrolysis method and a hydrogenation dehydrogenation method.

3. The method for refining the crystal grains of the alloy material in situ according to claim 1, wherein the temperature rise rate in the step 1) is 50-200K/min, and the temperature is kept for 1-10min after the temperature is raised to Ts.

4. The method for preparing the multi-scale structural alloy material according to claim 1, wherein the steps 1) -3) are performed in a sintering device with a thermal-force coupling field, such as a spark plasma sintering system, a hot pressing furnace device, a hot isostatic pressing device and the like.

5. The method for preparing the multi-scale structural alloy material according to claim 1, wherein when the sintering mold is a graphite mold, the sintering pressure in step 1) is 20 to 50MPa, and the cooling pressure is 100 to 200 MPa; when the sintering mold is a tungsten carbide mold, the sintering pressure in the step 1) is 50-100 MPa, and the cooling pressure is 200-500 MPa.

6. The method for preparing the multi-scale structural alloy material according to claim 1, wherein the phase transition peak is obtained from alloy powder through DSC test or DMA test.

7. A multi-scale structural alloy material, which is prepared by the method for preparing the multi-scale structural alloy material according to any one of claims 1 to 6.

8. The multi-scale structural alloy material according to claim 7, wherein the alloy material is selected from any one of Fe-based, Ti-based, Cu-based, Ni-based, Zr-based, Co-based, Cr-based, Mn-based, Mo-based, or Ta-based alloy systems.

9. The multi-scale structured alloy material according to claim 7, wherein the microstructure of the alloy material is a multi-scale structure comprising at least two of nano-crystalline, ultra-fine crystalline, or fine crystalline.

10. Use of the multi-scale structural alloy material according to any one of claims 7 to 9 for the production of parts in any one of the fields of high speed trains, automobiles, aerospace, military industry or instrumentation.

Technical Field

The invention belongs to the technical field of alloy material preparation, and particularly relates to a multi-scale structure alloy material, a preparation method and application thereof.

Background

With the development and progress of the national science and technology, the aim of preparing alloy materials with higher toughness to meet the application under more severe conditions is always pursued by researchers. The strengthening and toughening approach of the alloy material has been gradually developed to diversified processing technologies through deposition and inheritance for decades. According to the classical theory that the microstructure of the material determines the macroscopic performance, the final goal of researchers is to effectively optimize the comprehensive performance, especially the mechanical performance, of the alloy material by precisely controlling the microstructure (phase composition, grain size, distribution position and specific form) of the alloy material so as to achieve the final purpose of strengthening and toughening the alloy material.

In recent years, ultra-fine (100nm-1m) and nano-crystalline (100nm) materials have become a research hotspot in the material field because of their considerable strengthening effect. The nano alloy material is a metal and an alloy in which nano crystals are formed. At present, the common processing technology for preparing nano-structured metals and alloys mainly comprises a large plastic deformation method, and crystal grains are refined through dislocation accumulation and rearrangement. In addition, there are also electrodeposition and other processes, and the nanocrystalline can be prepared by controlling a deposition condition that promotes a large amount of nucleation but inhibits grain growth. These are based on Hall-Petch fine grain strengthening theory, and the main strengthening strategies of alloy materials are proposed. The Hall-Petch fine grain strengthening theory indicates that as grain size decreases, unprecedented high strength can be achieved. However, various studies have shown that nanocrystalline alloy materials, while achieving high strengths 5-10 times as high as the original macrocrystalline material, exhibit low plasticity, essentially due to limited dislocation storage and work hardening capabilities within the ultrafine grains. In contrast, high plasticity, microcrystalline (1m) structured alloy materials also appear to be favored.

Based on the above contradiction problems, in recent years, researchers have broken through a series of design strategies, and the processes can prepare nanocrystalline in alloy materials and obtain high strength, and simultaneously retain most of microcrystalline structures to greatly improve the plasticity of the materials. The preparation strategy of the 'double-scale' and 'multi-scale' microstructure provided by scientific researchers is that the multi-scale structure alloy material with coexistence of any two or more than two kinds of scale grains in a plurality of scale grains such as nano-crystal (100nm), ultra-fine crystal (100nm-1m), micron crystal (1-2m) and the like is prepared. The measure can be used for the strengthening engineering application of the nano or ultra-fine grain material, and simultaneously can improve the comprehensive mechanical property of the traditional cast coarse grain material, so that the alloy material has higher strength and plasticity.

At present, the main methods for preparing the alloy material with the double-scale/multi-scale structure include plastic deformation of block alloy and recrystallization induced by heat treatment, a solid-state sintering method and a gradient sintering method of alloy powder with different grain diameters, a semi-solid processing technology, a semi-solid sintering technology based on powder metallurgy and the like, and the double-scale structure with coarse crystal phases dispersed in a fine crystal matrix can be prepared. However, the methods have the problems of complex subsequent treatment process, complicated preparation of raw material powder, difficult preparation of semisolid slurry, uncontrollable solid-liquid volume fraction ratio and the like, so that the methods are difficult to popularize in more alloy systems and prepare high-density high-performance alloy materials with controllable microstructures. Therefore, it is an urgent need in the art to develop a simple and easy-to-operate method for synthesizing multi-scale structural alloy materials to reduce environmental pollution, save manpower, time and energy, and obtain high-quality multi-scale structural alloy materials.

Disclosure of Invention

The invention provides a multi-scale structural alloy material, a preparation method and application thereof, and develops a simple and easy-to-operate material forming preparation method, combines the preparation and subsequent treatment technologies of the alloy material into a whole, realizes the integrated forming of the dual-scale/multi-scale nano/superfine crystal structural alloy material, and prepares the high-toughness alloy material by regulating and controlling the microstructure structure form, the crystal grain size and the like in the alloy in situ.

The preparation method of the multi-scale structure alloy material provided by the invention comprises the following steps:

1) powder densification and sintering: the alloy powder is filled into a sintering die, and sintering is carried out after prepressing, wherein the sintering pressure is 20-100 MPa, and the sintering temperature Ts satisfies the following requirements: the starting temperature of the phase transition peak of the alloy powder is less than or equal to Ts and less than or equal to the ending temperature of the phase transition peak of the alloy powder;

2) high-pressure treatment: after sintering, pressurizing and cooling, wherein the cooling pressure is 10-500 MPa;

3) pressure relief and cooling: and when the pressure cooling temperature is reduced to 550-600 ℃, rapidly relieving the pressure, and cooling to obtain the alloy material.

Based on the method, the phase transition peak of the alloy powder is used, the sintering temperature of the alloy powder is selected, the alloy powder is sintered and densified, then high pressure is applied to the sintered and densified alloy powder to carry out in-situ crushing, grain refinement and redistribution treatment, and finally pressure relief cooling is carried out in a low-temperature region to realize the same effect of recrystallization/stress relief annealing treatment, so that multi-scale structures comprising at least two of nano-crystal, ultra-fine crystal or fine crystal are obtained, and the prepared alloy material has higher strength and high plasticity.

Based on the method of the invention, the following beneficial effects can be brought:

(1) based on the method, the microstructure of the material is regulated and controlled by combining powder metallurgy, plastic deformation and recrystallization/stress relief annealing to obtain the novel multi-scale-structure high-strength and high-toughness alloy, and compared with the traditional powder metallurgy sintering and bonding alloy, the yield strength, the tensile strength and the breaking strain of the alloy are respectively increased by 210 +/-10 MPa, 240 +/-10 MPa and 4.3 +/-0.5 percent.

(2) The in-situ grain refinement in the invention is carried out by applying high pressure to the powder sintering die, so that the in-situ grain refinement method can be used for preparing alloy pieces with larger sizes, complicated shapes and suitable for engineering application according to the design of the shape and the size of the die, and has wider universality and practicability.

(3) The in-situ refined crystal grains can induce structural crushing and grain refinement to improve the strength of the material, and the subsequent pressure relief cooling process can also lead the crystal grains with irregular shapes to be spheroidized and equiaxial, thereby improving the plasticity of the material.

(4) The in-situ grain refinement related to the invention is a process of carrying out in-situ plastic deformation on a densified and sintered block alloy in a high-temperature region, crushing, refining and rearranging a microstructure of the alloy, and carrying out recrystallization/stress relief annealing in a low-temperature region, wherein the process can not only regulate and control the microstructure, the dimension and the form of the internal microstructure of an alloy piece, but also eliminate quality defects of internal pores, thermal stress and the like, and can simultaneously improve the internal quality and the mechanical comprehensive performance of the alloy piece.

(5) Based on the method, compared with the deformation-induced recrystallization grain refinement technology in the prior art, the induced superfine crystal and nanocrystal only occur in a brittle phase region in the alloy, a plastic matrix phase is still reserved, the prepared nanocrystal and superfine crystal belong to in-situ generation, the problem of poor wettability among the phases does not exist, and the performance of the obtained alloy is more excellent; compared with the traditional powder metallurgy technology which can only prepare the organizational structure with single scale and form, the alloy part prepared by the in-situ refined grain sintering technology can realize grain refining, equiaxial crystallization, double-scale/multi-scale, compounding and gradient in the microstructure, so that the alloy material prepared by the in-situ refined grain sintering technology has more excellent comprehensive performance; compared with the traditional plastic deformation and heat treatment induced recrystallization grain refinement technology, the in-situ grain refinement sintering preparation method adopted by the invention is a technology integrating material preparation, plastic deformation and post heat treatment, has the advantages of simplicity, easiness in operation, high controllability, small interference, integration of processing and heat treatment and the like, greatly reduces the processing cost, has higher requirement on ductility of the original alloy material (more than 70 percent of deformation) and is difficult to apply to a hard-brittle alloy system, can be used for various alloy systems, can be an alloy material with good plasticity and an alloy material with slightly poor plasticity, and has important engineering significance on popularization of a nano-structure high-strength and toughness alloy material.

On the basis of the scheme, the invention can be further improved as follows:

further, the alloy powder is prepared by any one of an atomization method, a high-energy ball milling method, an electrolysis method or a hydrogenation and dehydrogenation method.

Specifically, the alloy powder used in the present invention is an alloy powder conventionally used in metal preparation in the field, and may be a powder prepared by various methods such as an atomization method, a high-energy ball milling method, an electrolysis method, a hydrogenation dehydrogenation method, etc., and the particle size and the thickness are not particularly limited, and the raw material may be one alloy powder or a mixed powder of a plurality of alloys.

Further, in the step 1), the heating rate is 50-200K/min, and after the temperature is increased to Ts, the heat preservation time is 1-10 min.

The faster the heating rate, the shorter the heat preservation time, the finer the tissue, and the better the effect of breaking the tissue when the pressure is increased later.

Specifically, the pre-pressing pressure is adjusted according to the actual condition, and is preferably 5-20 MPa.

The function of pre-pressing is to compact the loose powder to a certain extent, which is beneficial to further densification during the subsequent sintering, and the powder with different particle sizes and different components have different requirements on the initial pressure.

Further, the steps 1) -3) are carried out in a sintering device with a thermal-force coupling field, such as a spark plasma sintering system, a hot pressing furnace device, a hot isostatic pressing device and the like.

The discharge plasma sintering technology integrates plasma activation, hot pressing and resistance heating, has the characteristics of high temperature rise speed, short sintering time, quick cooling, controllable external pressure and sintering atmosphere and the like, and can fully meet the preparation requirement of the invention.

Further, when the sintering mold is a graphite mold, the sintering pressure in the step 1) is 20-50 MPa, and the cooling pressure is 100-200 MPa; when the sintering mold is a tungsten carbide mold, the sintering pressure in the step 1) is 50-100 MPa, and the cooling pressure is 200-500 MPa.

According to the properties of the alloy to be prepared, a corresponding sintering mold and pressure conditions are selected, a graphite mold is generally adopted for soft alloy, and a tungsten carbide mold is generally adopted for hard alloy.

Further, the phase transition peak is obtained from the alloy powder by a DSC test or a DMA test.

One or more phase transition peaks of the alloy material and the starting temperature and the ending temperature of each phase transition peak can be obtained through differential scanning calorimetry (DCS) and Dynamic Mechanical Analysis (DMA), so that the starting temperature and the ending temperature of the phase transition peaks of the alloy powder can be obtained.

The invention also provides a multi-scale structure alloy material which is prepared according to the preparation method of the multi-scale structure alloy material.

The method can prepare and form the high-toughness alloy material with larger size, complex shape and microstructure of double-scale/multi-scale structure containing nano-crystal, ultra-fine crystal and fine crystal, and overcomes the problems that the traditional processing technology is difficult to obtain high compactness, has no quality defect, contains the nano-crystal, ultra-fine crystal and has double-scale or multi-scale structure and the like.

Further, the alloy material is selected from any one of Fe-based, Ti-based, Cu-based, Ni-based, Zr-based, Co-based, Cr-based, Mn-based, Mo-based or Ta-based alloy systems.

The preparation method based on the invention has universal applicability to different alloy systems, and can obtain high-strength and high-toughness alloy materials with multi-scale structures.

Further, the microstructure of the alloy material is a multi-scale structure containing at least two of nano-crystalline, ultra-fine crystalline or fine crystalline.

The invention also provides application of the multi-scale structural alloy material, which is used for preparing parts in any field of high-speed trains, automobiles, aerospace, military industry or instruments.

The high-toughness alloy material prepared by the invention has a novel microstructure, and the microstructure structure of the high-toughness alloy material comprises at least two multi-scale structures of nano-crystalline, ultra-fine crystalline or fine crystalline, so that the high-toughness alloy material has excellent comprehensive performance and can be widely applied to parts in the fields of high-speed trains, automobiles, aerospace, war industry and instruments and meters.

The invention overcomes the common basic problems of single internal organization structure, narrow scale scope and the like of the traditional powder metallurgy prepared alloy, complex working procedures of traditional plastic deformation and recrystallization grain refinement induced by heat treatment, uncontrollable grain size and the like, regulates and controls the internal organization structure of an alloy piece, improves the mechanical comprehensive performance of the alloy piece, is suitable for preparing high-strength and high-toughness metal materials and parts thereof with larger size, complex shape and suitable for engineering application, the method has wide universality and practicability, and has good popularization and application prospects in parts in the fields of high-speed trains, aerospace, military industry, instruments and meters and the like.

Drawings

FIG. 1 is a scanning electron microscope image of an alloy material prepared by a conventional sintering method.

FIG. 2 is a scanning electron microscope image of the alloy material prepared in example 1.

Fig. 3 is an enlarged view of a and b in fig. 2.

Fig. 4 is a tensile stress-strain curve of the alloy material prepared in example 1 and the alloy material prepared in comparative example 1.

Detailed Description

The following detailed description of embodiments of the invention is intended to be illustrative, and is not to be construed as limiting the invention.

The invention is described below with reference to specific embodiments in conjunction with fig. 1-3.