A kind of NiTi fiber reinforced FeAl layered material of shell structure imitation and its preparation method

Abstract

The application discloses a kind of NiTi fiber reinforced FeAl layered materials of shell structure imitation and preparation method thereof, and the raw material used is 0.20~1.00mm thick 304SS (stainless steel) foil, 0.01~0.10mm thick 430SS (stainless steel) foil, 0.01~0.10mm thick commercial pure aluminum foil and diameter is 0.02~0.10mm NiTi fiber.The application adopts the method of "two stages+multiple thin foil" to prepare NiTi fiber reinforced FeAl series MIL composite material with multiple scale structure.The purpose of "two stages" sintering is to obtain multiple scale structure, eliminate brittle Fe2Al5 phase, form ductile FeAl phase, and improve the toughness of composite material;The purpose of "multiple thin foil" is to obtain multiple scale structure while reducing reaction time.To further increase the strength and toughness of the material, high strength and toughness NiTi fiber is also introduced, which can improve the toughness of intermetallic compound and obtain excellent mechanical properties.In addition, the addition of NiTi fiber also improves the sound absorption performance of the composite material.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of preparation of bionic composite materials, and particularly relates to a bionic shell structure NiTi fiber reinforced FeAl layered material and a preparation method thereof. BACKGROUND

[0002] Metal-Intermetallic-Laminate (MIL) is a new type of material imitating the laminated structure of natural shell, and is an important alternative material in the fields of aerospace and the like due to low density, high specific strength, high specific stiffness and good impact resistance. In recent years, various technologies have been used to prepare MIL composite materials of Ti-Al system, Ti-Ni system, Fe-Al system and Ni-Al system, and the most in-depth research belongs to the Ti-Al system. However, due to the fact that brittle Al3Ti is the only intermetallic phase formed in the reaction sintering process, the ability to adjust the performance is limited, and the cost of titanium alloy is relatively high, which to some extent limits the wide application of the Ti-Al system MIL composite material. The Fe-Al system MIL composite material is considered to be a new type of material with important development prospects due to the fact that it has strength and toughness not inferior to the Ti-Al system MIL composite material and the raw material cost is relatively low.

[0003] The preparation methods of Fe-Al MIL composites include rolling, hot-pressing sintering and spark plasma sintering. Among them, hot-pressing sintering is widely used due to its near-net-shape, strong interface bonding and no porosity. Vecchio's research found that the efficiency of Fe-Al MIL composites prepared by solid / semi-solid hot-pressing sintering is the highest, and the intermetallic compound layer is the densest. Subsequent research showed that heat treatment at a higher temperature after reaction sintering can convert the brittle Fe2Al5 phase into ductile FeAl phase, avoiding the intermetallic layer cracking due to stress during cooling. Wang Haoren abandoned the traditional thick foil stacking method, and prepared Fe-FeAl, 430SS-FeAl and 304SS-FeAl MIL composites by stacking thin iron and aluminum foils alternately. The compressive strength of the three composites in the direction perpendicular to the stacking direction is very high, reaching 1250 MPa, 1390 MPa and 2300 MPa, respectively, and the maximum plastic strain is ~0.17, ~0.11 and ~0.17, respectively. The compressive strength in the direction parallel to the stacking direction is 1750 MPa, 1760 MPa and 2000 MPa, respectively, and the maximum plastic strain is ~0.23, ~0.17 and ~0.19, respectively. Zheng Yuxing of Harbin Engineering University prepared FeAl MIL composites using pure iron foil, pure aluminum foil and 430SS foil, and the compressive strength perpendicular to the layer reached 2538 MPa, the compressive strength parallel to the layer reached 2417 MPa, and the tensile strength was 528 MPa. Wang Yu of North University used 1100 pure Al and pure Fe as raw materials to prepare three kinds of Fe-FeAl MIL composites by hot-pressing sintering and spark plasma sintering. The compressive strength perpendicular to the stacking direction is 1210 MPa-1450 MPa. However, the composites prepared by them are only at the mesoscale, and do not have the structure of macro-mesoscopic-micro multi-scale and multi-level.

[0004] Recently, in order to further improve the performance of MIL composites, researchers at home and abroad introduce continuous fibers into MIL composites, including NiTi, C, SiC, Al2O3, etc. Wang Enhao et al. introduced NiTi fibers into Ti-Al MIL materials, and measured the mechanical properties by compression test. The experimental results show that the average compressive strength and failure strain perpendicular to the layer are 1208 MPa and ~ 0.044, respectively, and the average compressive strength and failure strain parallel to the layer are 962 MPa and ~ 0.048, respectively. In addition, the addition of NiTi fibers can also improve the damping performance of the composite. Under the condition of 1Hz and 20Hz, the loss modulus is about 3500MPa and 4100MPa respectively from room temperature to 50℃. Jiao Feifei et al. prepared C fiber reinforced Ti-Al MIL composites, and the average compressive strength and failure strain perpendicular to the layer are 727MPa and ~ 0.045, respectively, and the average compressive strength and failure strain parallel to the layer are 838MPa and ~ 0.016, respectively, and the average tensile strength and fracture strain are 193MPa and 0.063. Li Chunfa and Han Yuqiang et al. also studied the mechanical properties of SiC fiber and Al2O3 fiber reinforced Ti-Al MIL composites, which also have better strength and plasticity than Ti-Al MIL composites without fibers. It can be seen that the addition of fibers can improve the mechanical properties of MIL composites. SUMMARY

[0005] The purpose of the present application is to provide a kind of NiTi fiber reinforced FeAl laminated material with multi-scale structure, high strength and high toughness, lower cost and high forming rate, and a preparation method thereof.

[0006] The purpose of the present application is realized by the following technical solutions.

[0007] A kind of NiTi fiber reinforced FeAl laminated material with shellfish structure, the raw material used is 0.20-1.00mm thick 304SS foil, 0.01-0.10mm thick 430SS foil, 0.01-0.10mm thick commercial pure aluminum foil and diameter 0.02-0.10mm NiTi fiber.

[0008] A kind of preparation method of NiTi fiber reinforced FeAl laminated material with shellfish structure, specifically comprising the following steps:

[0009] Step one: use silicon carbide sandpaper to polish the foil, remove surface oxides, then place in a beaker filled with anhydrous ethanol, ultrasonic cleaning;After cleaning, use a hair dryer to dry its surface, and store in a dry sealed place for standby;

[0010] Step two: remove the protective coating on the surface of NiTi fiber with deoxidizer;

[0011] Step three: the stacked structure of the layered composite material is composed of n 304SS layers and n-1'multi-thin foil' combinations, i.e., '304SS-'multi-thin foil' combination-304SS-'multi-thin foil' combination-304SS-'multi-thin foil' combination-304SS'; the'multi-thin foil' combination is composed of m 1060 pure Al layers, m-1 430SS layers and NiTi fibers, and the stacking order is 'NiTi-Al-430SS-NiTi-Al-430SS-...-NiTi-Al'.

[0012] Step four: the stacked raw materials are clamped between the stainless steel backing plates of the thin graphite flat plates in the vacuum hot pressing furnace, heated from room temperature to 550 DEG C, and the pressure is kept below 3-8 MPa, and then the heat preservation is carried out in two stages: after heating to 550 DEG C-750 DEG C, the pressure is kept at 3-8 MPa for 2-5 h; after heating to 850 DEG C-1000 DEG C, the pressure is kept at 12-18 MPa for 2-5 h.

[0013] Step five: after the heat preservation is completed, the finished product and the mold are cooled to room temperature in the furnace.

[0014] Further, in the step one, the foil is cut into a square of 50mm*50mm by a plate shearing machine, and the thickness of the 304SS foil, the 430SS foil and the commercial pure aluminum foil is 0.20-1.00mm, 0.01-0.10mm and 0.01-0.10mm respectively.

[0015] Further, in the step two, the diameter of the NiTi fiber is 0.02-0.10mm; and the deoxidizer is 25% HF, 15% HNO3 and 10% HCl.

[0016] Further, in the step three, the ratio of the metal layer and the intermetallic compound layer is adjusted by controlling the values of n and m, so as to adjust the performance.

[0017] Further, in the step four, the stacked raw materials are clamped between the stainless steel backing plates of the thin graphite flat plates in the vacuum hot pressing furnace, and heated from room temperature to 550 DEG C at a heating speed of 10 DEG C / min; in the first stage of heat preservation, the temperature is heated to 550 DEG C-750 DEG C at a speed of 1 DEG C / min; in the second stage of heat preservation, the temperature is heated to 850 DEG C-1000 DEG C at a speed of 5 DEG C / min.

[0018] The beneficial effects of the present application are as follows:

[0019] (1) The FeAl layered composite material prepared by the present application is a multi-phase mixed layer, which includes a metal layer, an intermetallic compound layer and a transition layer formed by Al diffusion, and is significantly different from the traditional TiAl and NiAl layered composite materials.

[0020] (2) The NiTi fiber introduced in the present application can be well combined with the matrix to form a fiber reaction zone without obvious defects. This can effectively improve the microstructure and mechanical properties of the FeAl layered composite.

[0021] (3) The FeAl layered composite prepared in the present application has a multi-scale structure similar to a shell. The multi-scale structure of the composite is the key to the synergistic energy dissipation mechanism and the basis for obtaining super high strength and toughness.

[0022] (4) The FeAl layered composite prepared in the present application has excellent sound absorption performance. This is due to the good damping and sound absorption performance of the NiTi fiber and the existence of small pores between the fiber and the matrix after the introduction of the NiTi fiber. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a schematic diagram of the stacking mode of the raw materials;

[0024] Figure 2 is the morphology of the FeAl MIL composite prepared in the present application at different scales;

[0025] Figure 3 is the compressive stress-strain curve of the FeAl MIL composite prepared in the present application in different directions;

[0026] Figure 4 is the tensile stress-strain curve of the FeAl MIL composite prepared in the present application (parallel to the NiTi fiber) and the FeAl MIL composite without adding NiTi fiber;

[0027] Figure 5 is the tensile fracture morphology of the FeAl MIL composite prepared in the present application;

[0028] Figure 6 is the sound absorption coefficient curve of the FeAl MIL composite prepared in the present application and the FeAl MIL composite without adding NiTi fiber. DETAILED DESCRIPTION

[0029] The present application will be further described below in conjunction with the drawings.

[0030] The present application belongs to the field of intermetallic compound laminated composite material preparation, and adopts a method of "two-stage + multiple thin foils" to prepare a NiTi fiber reinforced FeAl series MIL composite material with a multi-scale structure. The purpose of the "two-stage" sintering is to obtain a multi-scale structure, eliminate the brittle Fe2Al5 phase, form a ductile FeAl phase, and improve the toughness of the composite material; the purpose of the "multiple thin foils" is to obtain a multi-scale structure while reducing the reaction time. In order to further increase the strength and toughness of the material, high-strength and high-toughness NiTi fibers are introduced, which can improve the toughness of the intermetallic compound and obtain excellent mechanical properties. In addition, the addition of NiTi fibers also improves the sound absorption performance of the composite material.

[0031] To realize the present application, the specific technical scheme adopted is:

[0032] (1) Cut 0.20-1.00mm thick 304SS foil, 0.01-0.10mm thick 430SS foil, and 0.01-0.10mm thick commercial pure aluminum foil into 50mm x 50mm squares with a plate shearing machine. Polish the foils with silicon carbide sandpaper to remove surface oxides, then place them in a beaker filled with anhydrous ethanol and ultrasonically clean them. After cleaning, dry the surface with a hair dryer and store in a dry sealed place for later use.

[0033] (2) Select NiTi fibers with a diameter of 0.02-0.10mm, remove the protective coating on the surface of the NiTi fibers with a deoxidizer (25% HF, 15% HNO3 and 10% HCl), and then place them in a beaker filled with anhydrous ethanol and ultrasonically clean them. Dry and store for later use.

[0034] (3) The stacking structure of the laminated composite material is composed of n 304 stainless steel layers (304SS) and n-1 "multiple thin foils", i.e. "304SS -'multiple thin foils' combination - 304SS -'multiple thin foils' combination - 304SS……-'multiple thin foils' combination - 304SS". The "multiple thin foils" combination is composed of m 1060 pure Al layers, m-1 430 stainless steel layers (430SS) and NiTi fibers, and the stacking order is, for example, "NiTi - Al - 430SS - NiTi - Al - 430SS -……- NiTi - Al". The stacking diagram is shown in Figure 1 . The ratio of metal layers and intermetallic compound layers can be controlled by controlling the values of n and m, thereby controlling the performance.

[0035] (4) The stacked raw materials are clamped between the thin graphite flat plate stainless steel backing plates in the vacuum hot pressing furnace, heated from room temperature to 550℃ at a heating rate of 10℃ / min, the pressure is kept below 3-8MPa, and then the holding is carried out in two stages: the first stage is heated to 550-750℃ at a rate of 1℃ / min, and then held for 2-5h, the pressure is kept at 3-8MPa; the second stage is heated to 850-1000℃ at a rate of 5℃ / min, and then held for 2-5h, the pressure is kept at 12-18MPa.

[0036] (5) After the holding is completed, the finished product and the mold are cooled to room temperature with the furnace.

[0037] The structure of the present application at different scales is shown in Figure 2 The composite material has 6 metal layers and 5 intermetallic compound layers, and the intermetallic compound layer is obtained by reacting 7 layers of Al and 6 layers of 430SS. At the macroscopic scale, the obvious delamination of the composite material can be found; at the mesoscopic scale, it can be observed that the FeAl MIL composite material is composed of metal layers, intermetallic compound layers and transition layers, and the fiber is tightly combined with the intermetallic compound layer; at the microscopic scale, it can be clearly seen that the intermetallic compound layer is composed of multiple parallel sub-layers, the grain boundaries in each layer and the NiTi fiber in the intermetallic layer, and the grain size in the intermetallic compound layer is obviously smaller than that in the transition layer, especially near the NiTi fiber and the center line, which is caused by the oxides or impurities on the foil and fiber surface inhibiting the grain growth.

[0038] The quasi-static compression test results of the present application are shown in Figure 3 In the direction perpendicular to the stacking direction, the strength reaches 3895MPa, which is increased by 40.6% compared with the composite material without fiber and without multi-scale structure. In the direction parallel to (including parallel and perpendicular to the NiTi fiber) the stacking direction, the strength is 3401MPa and 2824MPa respectively, which is increased by 68.8% and 40.1% respectively compared with the composite material without fiber and without multi-scale structure.

[0039] The quasi-static tensile test results of the present application are shown in Figure 4 The tensile direction is parallel to the laying direction of the NiTi fiber. The average yield strength, ultimate tensile strength and fracture strain of the NiTi fiber reinforced FeAl MIL composite material with multi-scale structure are 358.0MPa, 424.4MPa and 7.4% respectively, which are increased by 20.6%, 24.2% and 1.4% respectively compared with the FeAl MIL composite material without NiTi fiber. The tensile fracture morphology is shown in Figure 5The fracture mode of the Fe-Al MIL composite material with a multi-scale structure is a mixed ductile-brittle fracture, and the NiTi fibers are debonded, pulled out and fractured. These multiple reinforcement mechanisms can improve the tensile properties of the composite material by absorbing energy.

[0040] The sound absorption coefficient curve is obtained by averaging three repeated experiments. The sound absorption performance of the FeAl MIL composite material prepared by the application and the FeAl MIL composite material without NiTi fibers is compared, and the results are shown in Figure 6 The sound absorption coefficient of the FeAl MIL composite material prepared by the application is the highest at a low frequency of 1200Hz, about 0.51. Compared with the FeAl MIL composite material without NiTi fibers (the highest sound absorption coefficient is about 0.19), after adding the fibers, not only multiple absorption peaks appear, but also the sound absorption coefficient is improved by about 170%. On the one hand, this is related to the high damping sound absorption performance of the NiTi fiber with shape memory effect; on the other hand, the gap formed between the fiber and the matrix can play a certain sound absorption effect.

[0041] In summary, the application belongs to the field of intermetallic compound layered composite material preparation, and aims to provide a NiTi fiber reinforced FeAl layered material with a shellfish structure and a preparation method thereof. The strength and toughness of the composite material are improved by using the synergistic energy dissipation mechanism of the multi-scale structure, and the sound absorption performance of the FeAl MIL composite material is improved by introducing the NiTi fiber with shape memory effect and super elasticity. The application is prepared by using the "two-stage + multi-thin foil" method, which shortens the reaction time while ensuring the multi-scale structure, effectively solving the problem of long solid-solid reaction time of the MIL composite material. The raw materials used in the application are low in cost, and by changing the ratio of the 430SS layer and the Al layer in the "multi-thin foil" combination, the requirements of different application occasions can be met.

[0042] The above only describes the preferred embodiments of the application and is not intended to limit the application. For those skilled in the art, the application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A NiTi fiber-reinforced FeAl layered material with a shell-like structure, characterized in that: It is composed of n 0.20~1.00mm thick 304SS foils and n-1 multi-thin foil combinations stacked alternately; each multi-thin foil combination is composed of m 0.01~0.10mm thick 1060 pure Al foils, m-1 0.01~0.10mm thick 430SS foils and NiTi fibers with a diameter of 0.02~0.10mm stacked in the order of NiTi—Al—430SS—NiTi—Al—430SS—……—NiTi—Al.

2. The method for preparing a shell-like NiTi fiber-reinforced FeAl layered material according to claim 1, characterized in that: Specifically, the following steps are included: Step 1: Use silicon carbide sandpaper to polish the foil to remove surface oxides, then place it in a beaker filled with anhydrous ethanol for ultrasonic cleaning; after cleaning, use a hair dryer to dry the surface and store it in a dry and sealed place for later use. Step 2: Remove the protective coating on the surface of the NiTi fiber using a deoxidizer; Step 3: The stacked structure of the layered composite material consists of n 0.20~1.00mm thick 304SS foils and n-1 multi-thin foil combinations stacked alternately; each multi-thin foil combination consists of m 0.01~0.10mm thick 1060 pure Al foils, m-1 0.01~0.10mm thick 430SS foils, and NiTi fibers with a diameter of 0.02~0.10mm stacked in the order of NiTi—Al—430SS—NiTi—Al—430SS—……—NiTi—Al; Step 4: The stacked raw materials are sandwiched between stainless steel plates of thin graphite plates in a vacuum hot press furnace and heated from room temperature to 550℃, with the pressure maintained at 3-8MPa. Then, the temperature is maintained in two stages: the first stage is heated to 550℃-750℃ and held for 2-5 hours, with the pressure maintained at 3-8MPa; the second stage is heated to 850℃-1000℃ and held for 2-5 hours, with the pressure maintained at 12-18MPa. Step 5: After the heat preservation is completed, the finished product and the mold are cooled to room temperature along with the furnace.

3. The method for preparing a shell-like NiTi fiber-reinforced FeAl layered material according to claim 2, characterized in that: In step one, the foil material is cut into 50mm×50mm squares by a shearing machine using 304SS foil with a thickness of 0.20~1.00mm, 430SS foil with a thickness of 0.01~0.10mm, and commercial pure aluminum foil with a thickness of 0.01~0.10mm.

4. The method for preparing a shell-like NiTi fiber-reinforced FeAl layered material according to claim 2, characterized in that: In step four, the stacked raw materials are sandwiched between stainless steel pads on thin graphite plates in a vacuum hot press furnace and heated from room temperature to 550°C at a heating rate of 10°C / min. During the first stage of heat preservation, the materials are heated to 550°C-750°C at a rate of 1°C / min. During the second stage of heat preservation, the materials are heated to 850°C-1000°C at a rate of 5°C / min.

Images