Amorphous whisker material and preparation method thereof

Abstract

The invention belongs to the field of novel materials, and discloses an amorphous whisker material and a preparation method thereof, and the method comprises the steps of Fe-Cr-B cast steel hot dip coating of Al-Ga-Si alloy, diffusion heat treatment and ZnCl2 molten salt corrosion. Fe-Cr-B cast steel is subjected to Al-Ga-Si alloy hot dipping-diffusion heat treatment, then a periodic lamellar structure formed by alternately arranging Cr-(Al, Ga)-B MAB phase solid solutions and FeAl3 is generated on a (Cr, Fe) 2 / Al-Ga alloy melt solid-liquid interface, and after the cross section is subjected to polishing treatment, amorphous Al (Ga) solid solution whiskers can spontaneously grow on the Cr-(Al, Ga)-B MAB phase solid solutions; and then the plating layer of the periodic lamellar structure is immersed in ZnCl2 fused salt at the temperature of 450-750 DEG C for a certain time (0.5-2 h) and then taken out, and after the cross section is polished, amorphous (Al, Ga) 2O3 solid solution whiskers can be spontaneously grown on the Cr-(Al, Zn, Ga)-B MAB phase solid solution. According to the invention, a plurality of MAB phase solid solutions are prepared through a simple process, and different types of amorphous whiskers can spontaneously grow.

Description

Technical Field

[0001] This invention relates to the field of novel materials, and particularly to amorphous whisker materials and their preparation methods. Background Technology

[0002] MAB phase is a special type of boride with a layered atomic arrangement, where M is a transition metal, A is a group 13-16 element, and B is boron. MAB phases are mostly prepared using methods such as spark plasma sintering, which require high reaction temperatures and holding times, resulting in significant energy consumption. Furthermore, the prepared MAB phase often contains numerous impurities. The applicant has long been engaged in research on hot-dip aluminizing of steel and has discovered that during hot-dip aluminizing of Fe-Cr-B cast steel with specific compositions, a periodic lamellar (PLS) coating is formed in situ at the interface between (Cr, Fe)₂B and the molten aluminum. This PLS is composed of alternating FeAl₃ and Cr-Al-B MAB phases. The alloying elements such as Ti, Zn, and Sn in the molten aluminum significantly affect the composition of the Cr-Al-B MAB phase in PLS, generating solid solutions of MAB phases such as (Cr, Ti)-Al-B, Cr-(Al, Zn)-B, and Cr-(Al, Sn)-B, respectively. This means that Ti, Zn, and Sn atoms in the molten aluminum alloy can partially replace Cr and Al atoms at the M and A positions, respectively. Specifically, the Cr-(Al, Sn)-B MAB phase solid solution can spontaneously grow Sn whiskers, but the Cr-(Al, Zn)-B phase solid solution will not grow Zn whiskers.

[0003] The applicant also conducted research on the reaction of Fe-Cr-B cast steel treated with hot-dip aluminizing and diffusion heat treatment with molten salts such as ZnCl2. They found that the Cr-(Al, Zn)-B phase solid solution formed after ZnCl2 molten salt corrosion spontaneously grows Zn whiskers. Huang Qing et al. prepared Ti2ZnC using the reaction between the Ti2AlC MAX phase and ZnCl2 molten salt, but whiskers did not grow. However, Zhang Peigen et al.'s Ti2ZnC prepared using this reaction spontaneously grew ZnO whiskers after ball milling and cold pressing. Furthermore, apart from the applicant's research, there are few reports of A-site element whiskers growing in the MAB phase.

[0004] Therefore, the influence of different alloying elements on the Cr-Al-B MAB phase and its growth whiskers, especially the influence of different A-site alloying elements on the growth of A-site element whiskers in the MAB / MAX phase, is quite complex. For example, according to relevant literature, Sn whiskers can grow in the Ti2SnCMAX phase, but whiskers cannot grow in the Ti2(AlSn)CMAX phase solid solution. Therefore, further research is needed to investigate the influence of different forms (atomic and cation) of A-site alloying elements on the MAB phase and its growth whiskers. Furthermore, most existing amorphous materials are prepared through rapid solidification and other methods, which have high process requirements, and there are currently few reports on amorphous whisker materials. Summary of the Invention

[0005] In view of the problems existing in the prior art, the purpose of this invention is to provide an amorphous whisker material and a method for preparing the same.

[0006] The objective of this invention is achieved through the following technical solution: Amorphous whisker materials, including Al(Ga) and (Al, Ga)₂O₃ solid solutions, both of which are amorphous structures.

[0007] The method for preparing the amorphous whisker material includes the following steps: (1) Preparation of PLS ​​coating Fe-(15-30) wt.% Cr-(4-7) wt.% B cast steel was immersed in an Al-(10-40) wt.% Ga-(3-5) wt.% Si alloy melt for hot-dip aluminizing (750℃, 30 min). After a certain reaction time, the sample was quickly removed from the aluminum melt, air-cooled, and then subjected to diffusion heat treatment (750℃, 60 min). A PLS coating composed of alternating Cr-(Al, Ga)-B MAB phase solid solution and FeAl3 was formed at the interface of the boride (Cr, Fe)2B / Al-Ga alloy melt in the Fe-Cr-B cast steel. After mechanical polishing, amorphous Al(Ga) solid solution whiskers spontaneously grew on the Cr-(Al, Ga)-B MAB phase solid solution.

[0008] (2) ZnCl2 molten salt corrosion The PLS coating prepared in step (1) is immersed in ZnCl2 molten salt (450-750 ℃) for a certain time (5-60 min) and then taken out. After mechanical polishing, the cross section can spontaneously grow amorphous (Al, Ga)2O3 solid solution whiskers on the Cr-(Al, Zn, Ga)-B MAB phase solid solution.

[0009] Amorphous whisker materials: Al whiskers can grow spontaneously on amorphous Al(Ga) solid solution whiskers, and Ga whiskers can grow spontaneously on amorphous (Al, Ga)₂O₃ solid solution whiskers.

[0010] A method for preparing amorphous whisker materials, wherein step one can spontaneously grow amorphous Al(Ga) solid solution whiskers, and step two can spontaneously grow amorphous (Al, Ga)₂O₃ solid solution whiskers.

[0011] The preparation method of amorphous whisker material, in step one, the spontaneously growing amorphous Al(Ga) solid solution whiskers are approximately spherical with no striations on the surface, while in step two, the spontaneously growing amorphous (Al, Ga)2O3 solid solution whiskers are strip-shaped with deep longitudinal striations on the surface.

[0012] A method for preparing amorphous whisker materials, wherein in step one, the root of the amorphous Al(Ga) solid solution whisker spans several rows of Cr-(Al, Ga)-B MAB phase solid solution in PLS, and in step two, the amorphous (Al, Ga)2O3 solid solution whisker grows on the Cr-(Al, Zn, Ga)-B MAB phase solid solution.

[0013] The preparation method of amorphous whisker materials involves a Cr-(Al, Ga)-B MAB phase solid solution generated in step one, which transforms into a Cr-(Al, Zn, Ga)-B MAB phase solid solution in step two. The reaction expression is as follows: Cr3(Al, Ga)B4(s) + ZnCl 2(l) → Cr3(Al, Zn, Ga)B4(s) + Zn(l) + AlCl3(g).

[0014] The preparation method of amorphous whisker material, in step two, the spontaneously growing whiskers have a segmented structure, with the tip being a Zn(Al, Ga) solid solution and the bottom being an amorphous (Al, Ga)2O3 solid solution.

[0015] A method for preparing amorphous whisker materials, wherein step one involves a Cr-Al-B MAB phase matrix that is pushed out by the rapid growth of the whiskers in a spontaneously growing, approximately spherical amorphous Al(Ga) solid solution whisker.

[0016] Compared with the prior art, the present invention has the following advantages: 1. The process of hot-dip aluminizing Fe-Cr-B cast steel followed by chloride molten salt corrosion can be used to study the effects of A-site elements with different formation (atoms and cations) on the composition of Cr-Al-B MAB phase and the growth of whiskers. The process is simple and easy to operate.

[0017] 2. After Fe-Cr-B cast steel is hot-dip coated with Al-Ga alloy, Al(Ga) solid solution whiskers can grow spontaneously instead of Ga whiskers, especially amorphous Al(Ga) whiskers. This discovery overturns conventional knowledge that amorphous whiskers can be prepared through a simple process.

[0018] 3. After hot-dip aluminizing with Al-Ga alloy on Fe-Cr-B cast steel and then undergoing ZnCl2 molten salt corrosion, segmented whiskers spontaneously grow. The whisker tips are composed of amorphous (Al, Ga)₂O₃ solid solution, while the bottom is composed of Zn(Al, Ga) solid solution. Segmented whiskers containing amorphous components were prepared using a hot-dip aluminizing-molten salt corrosion process.

[0019] 4. On the aforementioned amorphous Al(Ga) and (Al, Ga)₂O₃ solid solution whiskers, ultrafine Al and Ga whiskers can spontaneously grow. Such secondary growth of whiskers with different compositions is relatively rare. Attached Figure Description

[0020] Figure 1 Microstructure of the cross-section of the Fe-Cr-B cast steel prepared in Example 1 by hot-dip aluminizing and diffusion heat treatment; Figure 2 High-magnification microstructure of the cross-section of the hot-dip aluminized and diffusion-heat-treated Fe-Cr-B cast steel prepared in Example 1; Figure 3 This is a high-magnification micrograph of the Cr element distribution in the cross-section of the Fe-Cr-B cast steel prepared in Example 1 by hot-dip aluminizing and diffusion heat treatment. Figure 4 Al element distribution diagram of the cross-section of the Fe-Cr-B cast steel prepared by hot-dip aluminizing and diffusion heat treatment in Example 1; Figure 5 The image shows the Ga element distribution in the high-magnification microstructure of the hot-dip aluminized and diffusion-treated Fe-Cr-B cast steel cross-section prepared in Example 1. Figure 6 Selected area electron diffraction spots of spherical Al(Ga) solid solution whiskers prepared in Example 1; Figure 7 High-magnification microstructure of the cross-section of the Fe-Cr-B cast steel prepared in Example 1 after hot-dip aluminized and diffusion heat-treated treatment and ZnCl2 molten salt corrosion; Figure 8 The high-magnification microstructure of the cross-section of the Fe-Cr-B cast steel prepared in Example 1 after hot-dip aluminizing and diffusion heat treatment followed by ZnCl2 molten salt corrosion is shown as the Al element distribution diagram. Figure 9The image shows the Ga element distribution of the cross-section of the Fe-Cr-B cast steel prepared in Example 1 after hot-dip aluminizing and diffusion heat treatment followed by ZnCl2 molten salt corrosion. Figure 10 The high-magnification microstructure of the cross-section of the Fe-Cr-B cast steel prepared in Example 1 after hot-dip aluminizing and diffusion heat treatment followed by ZnCl2 molten salt corrosion is shown as the Zn element distribution diagram. Figure 11 The image shows the O element distribution of the cross-sectional microstructure of the Fe-Cr-B cast steel prepared in Example 1 after hot-dip aluminizing and diffusion heat treatment and ZnCl2 molten salt corrosion. Figure 12 Selected area electron diffraction spots of (Al, Ga)₂O₃ solid solution whiskers prepared in Example 1.

[0021] Figure 13 The image shows a high-magnification microstructure of the cross-section of the Fe-Cr-B cast steel prepared in Example 3 after hot-dip aluminizing and diffusion heat treatment, followed by ZnCl2 molten salt corrosion. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0023] The Fe-Cr-B cast steel in the examples was prepared by the following method: Ingredients: Based on the designed alloy composition, calculate the required weight of micro-carbon ferrochrome Fe-58wt.%Cr-0.06wt.%C, Fe-18wt.%B master alloy and pig iron, with a total weight of 10kg.

[0024] Melting: The weighed raw materials from step ① are loaded into a vacuum melting furnace. After complete melting, the furnace is superheated to 1600℃ and held for 15 minutes. Then, the mixture is poured into a metal mold and cooled to obtain Fe-Cr-B cast steel.

[0025] The microstructure of the prepared Fe-Cr-B cast steel mainly consists of a grayish-black (Cr, Fe)₂B phase and grayish-white α-Fe. The microstructures in the examples were captured using a scanning electron microscope in backscattered electron mode; the whiter the area, the higher the average atomic number.

[0026] Example 1: Fe-Cr-B cast steel was hot-dip aluminized (750℃, 30 min) by immersion in an Al-20 wt.% Ga-3.5 wt.% Si alloy melt. After removal and cooling to room temperature, it underwent diffusion heat treatment in an electric resistance furnace (750℃, 60 min). After cooling, the cross-sectional microstructure was observed after electrical discharge machining and polishing. Figure 1As shown, nearly spherical whiskers can be seen spontaneously growing on the whitish PLS, with high magnification of the microstructure as follows: Figure 2 As shown, irregularly shaped whiskers can be seen to have grown secondary on the spherical whiskers. Elemental plane distribution analysis reveals that the plane distributions of Cr, Al, and Ga are as follows: Figure 3 , 4 As shown in Figure 5, Cr represents the position of the Cr-Al-B MAB phase in PLS. The distribution of Ga overlaps with the position of the Cr-Al-B MAB phase. Considering that Ga is the element at position A, it can be determined that a Cr-(Al, Ga)-B MAB phase solid solution was formed. The spherical whiskers mainly contain Al and a small amount of Ga. The selected area electron diffraction spots detected by transmission electron microscopy are shown in Figure 5. Figure 6 As shown, the Al(Ga) solid solution whiskers exhibit a typical concentric circle structure, thus indicating that they are amorphous. The surface of these Al(Ga) solid solution whiskers shows no obvious striations. Furthermore, these amorphous Al(Ga) solid solution whiskers contain a Cr-Al-B MAB phase matrix that is pushed out by the rapid growth of the whiskers.

[0027] The Fe-Cr-B cast steel, after hot-dip aluminizing and diffusion heat treatment, was immersed in ZnCl2 molten salt at 500℃ for 20 minutes, then removed, cooled, and polished. The cross-sectional microstructure was then observed as follows: Figure 7 As shown, combined with Figure 8 , 9 As shown in Figures 10 and 11, the surface distributions of Al, Ga, Zn, and O elements overlap with the positions of the Cr-Al-B MAB phase, indicating the formation of a Cr-(Al, Zn, Ga)-B MAB solid solution. Furthermore, segmented whiskers (with Zn(Al, Ga) solid solution at the upper end and (Al, Ga)₂O₃ solid solution at the lower end) spontaneously grow on this MAB solid solution, exhibiting deep longitudinal striations on their surface. The selected area electron diffraction (SED) spots of the (Al, Ga)₂O₃ solid solution at the lower end, as detected by transmission electron microscopy, are shown below. Figure 12 As shown, it exhibits a typical concentric circle structure, thus indicating that the whiskers of this (Al, Ga)₂O₃ solid solution are amorphous. Furthermore, combined with... Figure 8 , 9 As shown in Figures 10 and 11, the surface distributions of Al, Ga, Zn, and O elements respectively indicate that... Figure 7 Ga whiskers also grow on the (Al, Ga)2O3 solid solution whiskers in the lower right corner.

[0028] Example 2: Fe-Cr-B cast steel was immersed in an Al-12 wt.% Ga-4 wt.% Si alloy melt for hot-dip aluminizing (750℃, 30 min). After removal and cooling to room temperature, it underwent diffusion heat treatment in an electric resistance furnace (750℃, 60 min). After cooling, the cross-sectional microstructure was observed after electrical discharge machining and polishing. Approximately spherical whiskers were observed spontaneously growing on the whitish PLS. These whiskers were amorphous Al(Ga) solid solution whiskers with no obvious striations on the surface, but the surface contained Cr-Al-B MAB phase matrix pushed out by the whisker growth.

[0029] The Fe-Cr-B cast steel, after hot-dip aluminizing and diffusion heat treatment, was immersed in ZnCl2 molten salt at 700℃ for 5 minutes. After cooling, the cross-sectional microstructure was observed after polishing. Segmented whiskers (Zn(Al, Ga) solid solution at the upper end and (Al, Ga)2O3 solid solution at the lower end) spontaneously grew on the whitish Cr-Al-B MAB phase. The surface of the whiskers had deep longitudinal striations. The (Al, Ga)2O3 solid solution at the lower end was amorphous.

[0030] Example 3: Fe-Cr-B cast steel was immersed in an Al-40 wt.% Ga-5 wt.% Si alloy melt for hot-dip aluminizing (750℃, 30 min). After removal and cooling to room temperature, it underwent diffusion heat treatment in an electric resistance furnace (750℃, 60 min). After cooling, the cross-sectional microstructure was observed after electrical discharge machining and polishing. Approximately spherical whiskers were observed spontaneously growing on the whitish PLS. These whiskers were amorphous Al(Ga) solid solution whiskers with no obvious striations on the surface, but contained Cr-Al-B MAB phase matrix pushed out by the whisker growth.

[0031] The Fe-Cr-B cast steel, after hot-dip aluminizing and diffusion heat treatment, was immersed in ZnCl2 molten salt at 450℃ for 40 minutes. After cooling, the cross-sectional microstructure was observed after grinding and polishing. Segmented whiskers (with Zn(Al, Ga) solid solution at the upper end and (Al, Ga)2O3 solid solution at the lower end) spontaneously grew on the whitish Cr-Al-B MAB phase. The surface of these whiskers had deep longitudinal striations, such as... Figure 13 As shown, the (Al, Ga)₂O₃ solid solution at the lower end is amorphous.

[0032] The above-described specific embodiments are preferred embodiments of the present invention and are not intended to limit the present invention. Any other changes or equivalent substitutions made without departing from the technical solution of the present invention are included within the protection scope of the present invention.

Claims

1. An amorphous whisker material, characterized in that: The whisker material includes Al(Ga), (Al, Ga)2O3 solid solution, and both are in amorphous structure; The preparation method of the amorphous whisker material includes the following steps: (1) Preparation of PLS coating Fe-(15-30) wt. % Cr-(4-7) wt. % B cast steel is immersed into Al-(10-40) wt. % Ga-(3-5) wt. % Si alloy melt for hot-dip aluminizing (750 DEG C, 30 min), the sample is quickly taken out from the aluminum liquid after reacting for a certain time, and then air-cooled, followed by diffusion heat treatment (750 DEG C, 60 min), then a PLS coating composed of Cr-(Al, Ga)-B MAB phase solid solution and FeAl3 is generated on the interface of boride (Cr, Fe)2B / Al-Ga alloy melt in the Fe-Cr-B cast steel. After mechanical polishing treatment of the cross section, amorphous Al(Ga) solid solution whiskers are self-grown on the Cr-(Al, Ga)-B MAB phase solid solution; (2) ZnCl2 molten salt corrosion The PLS coating prepared in step (1) is immersed in ZnCl2 molten salt (450-750 DEG C) for a certain time (5-60 min), and then taken out, and after mechanical polishing treatment of the cross section, amorphous (Al, Ga)2O3 solid solution whiskers are self-grown on the Cr-(Al, Zn, Ga)-B MAB phase solid solution.

2. The amorphous whisker material of claim 1, wherein: Amorphous Al(Ga) solid solution whiskers can self-grow Al whiskers, and amorphous (Al, Ga)2O3 solid solution whiskers can self-grow Ga whiskers.

3. The method of claim 1, wherein: Amorphous Al(Ga) solid solution whiskers are self-grown in step one, and amorphous (Al, Ga)2O3 solid solution whiskers are self-grown in step two.

4. The method of claim 1, wherein: The amorphous Al(Ga) solid solution whiskers self-grown in step one are approximately spherical and have no stripes on the surface, while the amorphous (Al, Ga)2O3 solid solution whiskers self-grown in step two are strip-shaped and have deep longitudinal stripes on the surface.

5. The method of claim 1, wherein: The root of the amorphous Al(Ga) solid solution whiskers in step one spans several rows of Cr-(Al, Ga)-B MAB phase solid solutions in the PLS, and the amorphous (Al, Ga)2O3 solid solution whiskers in step two grow on the Cr-(Al, Zn, Ga)-B MAB phase solid solution.

6. The method of claim 1, wherein: The Cr-(Al, Ga)-B MAB phase solid solution generated in step one is converted into Cr-(Al, Zn, Ga)-B MAB phase solid solution after step two, and the reaction expression is as follows: Cr3(Al, Ga)B4(s) + ZnCl 2(l) → Cr3(Al, Zn, Ga)B4(s) + Zn(l) + AlCl3(g).

7. The method of claim 1, wherein: The whiskers self-grown in step two have a segmented structure, with the tip being Zn(Al, Ga) solid solution and the bottom being amorphous (Al, Ga)2O3 solid solution.

8. The method of claim 1, wherein: The approximately spherical amorphous Al(Ga) solid solution whiskers self-grown in step one contain a Cr-Al-B MAB phase substrate which is pushed out by the rapid growth of the whisker.

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