La (Fe, Si) 13 phase-based negative thermal expansion composite material and application

Abstract

The invention discloses a La (Fe, Si) 13 phase-based negative thermal expansion composite material and application, the composite material has the following general formula: z (LaFe13-x-yMySix) (100-z) Cu, M can be but not limited to Mn or Co, x is greater than or equal to 1.0 and less than or equal to 2.5, y is greater than or equal to 0 and less than or equal to 2, and z is greater than or equal to 55 and less than or equal to 100. The composite material has the characteristic of adjustable negative thermal expansion coefficient, has extremely high thermal and mechanical stability, and is of great significance to development of precision mechanical devices based on zero expansion.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of inorganic non-metallic materials, and particularly to a negative thermal expansion composite material based on La(Fe, Si) 13 phase and application. BACKGROUND

[0002] Due to the anharmonic thermal vibration of the crystal lattice, most materials have the characteristics of thermal expansion and contraction, that is, the volume of the material increases with the increase of temperature. The positive thermal expansion coefficient in general materials is relatively small, however, even a small positive thermal expansion can lead to the failure of the equipment in precision instruments, therefore, it is of great physical significance and application value to develop materials with negative thermal expansion or zero expansion.

[0003] In addition, by using negative thermal expansion materials and positive expansion materials to composite, the thermal expansion coefficient of the material can be controlled, which is also the main way to realize negative thermal expansion and zero expansion. The existing negative thermal expansion materials are mainly divided into two types: one is the negative thermal expansion caused by lattice vibration, and the representative materials are β-spodumene, β-albite, ZrW2O8; the other is the negative thermal expansion material caused by phase transition, including magnetic phase transition materials such as Hf(Ta, Fe)2, La(Fe, Si) 13 , Mn3AN; ferroelectric phase transition materials such as 0.4PbTiO3-0.6BiFeO3; structural phase transition materials such as MM’X (M, M’ = transition group elements, X is main group elements such as Ge, Si). The negative thermal expansion material based on phase transition is the main component of the negative thermal expansion material, however, the huge volume change during the phase transition of this kind of material will introduce internal stress, resulting in poor mechanical properties and difficulty in forming, and thus cannot be applied.

[0004] The La(Fe, Si) 13 based negative thermal expansion material based on magnetic phase transition has low cost, its thermal expansion has isotropic characteristics, and its electrical conductivity is high, which is a negative thermal expansion material with great application value. However, this kind of material will be broken during temperature change.

[0005] In view of the above reasons, it is urgent to explore a La(Fe, Si) 13 based negative thermal expansion material with excellent performance. SUMMARY

[0006] In order to overcome the above problems, the application provides a negative thermal expansion composite material based on La(Fe, Si) 13 phase and application, the composite material has the following general formula: z(LaFe 13-x-y M y Si x)(100-z)Cu, wherein M can be but is not limited to Mn or Co, 1.0<=x<=2.5, 0<=y<=2, 55<=z<=100. The composite material has the characteristics of adjustable negative thermal expansion coefficient and has extremely high thermal and mechanical stability, which is of great significance for the development of precision mechanical devices based on zero expansion, thereby achieving the present application.

[0007] Specifically, the present application aims to provide the following aspects:

[0008] In a first aspect, a negative thermal expansion composite material based on La(Fe,Si) 13 phase is provided, and the composite material has the general formula: z(LaFe 13-x-y M y Si x )(100-z)Cu, wherein M can be but is not limited to Mn or Co, 1.0<=x<=2.5, 0<=y<=2, 55<=z<=100.

[0009] In a second aspect, a preparation method for preparing the composite material of the first aspect is provided, and the method comprises:

[0010] Step 1: mixing and smelting metal elements to obtain a cast alloy ingot;

[0011] Step 2: annealing the cast alloy ingot to obtain a crude product;

[0012] Step 3: quenching the crude product to obtain the composite material.

[0013] The present application has the following beneficial effects:

[0014] (1) The negative thermal expansion composite material based on La(Fe,Si) 13 phase provided by the present application has the characteristics of adjustable negative thermal expansion coefficient, and has zero expansion effect and good mechanical properties.

[0015] (2) The negative thermal expansion composite material based on La(Fe,Si) 13 phase provided by the present application can obtain composite materials with different requirements from brittle to plastic by adjusting the content of Cu.

[0016] (3) The preparation method of the negative thermal expansion composite material based on La(Fe,Si) 13 phase provided by the present application is extremely simple and low in cost, and the obtained composite material has extremely high thermal and mechanical stability, which is of great significance for the development of precision mechanical devices based on zero expansion. BRIEF DESCRIPTION OF DRAWINGS

[0017] Various other advantages and benefits of the present application will become apparent to those of ordinary skill in the art, upon reading the following detailed description of the preferred embodiment. The accompanying drawings are included to provide a better understanding of the preferred embodiment, and are not intended to limit the scope of the application. It should be readily understood that the drawings are not to scale, and are merely intended to depict the general structure of the application.

[0018] In the drawings:

[0019] Figure 1 A graph showing the linear expansion of the composite material produced in Example 1 to Example 6 versus temperature;

[0020] Figure 2 A graph showing the compression curve of the composite material produced in Example 1 to Example 6;

[0021] Figure 3(a) shows the XRD pattern of the composite material produced in Example 1 ;

[0022] Figure 3(b) shows the XRD pattern of the composite material produced in Example 2;

[0023] Figure 3(c) shows the XRD pattern of the composite material produced in Example 5;

[0024] Figure 4(a) shows the backscattering pattern of the composite material produced in Example 1 ;

[0025] Figure 4(b) shows the backscattering pattern of the composite material produced in Example 2;

[0026] Figure 4(c) shows the backscattering pattern of the composite material produced in Example 5. DETAILED DESCRIPTION

[0027] Reference will now be made to the drawings in which the various embodiments of the present application are shown by way of example. Figures 1 to 4(c) Specific embodiments of the present application will now be described in more detail. While the embodiments of the application are shown in the drawings, it is understood that the application can be carried out in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the application to those skilled in the art.

[0028] It should be noted that some terms are used throughout the specification and claims which have obtained particular meanings. Those of ordinary skill in the art will appreciate that the same component can be referred to by different names and that such names by themselves do not affect or limit the component. The specification and claims should not be construed as indicating that the inventors are in any way limited in their preferred embodiments to the names of components. The words "comprise" or "comprising" are to be interpreted as non-limiting language that does not limit the scope of the claims. The description that follows is intended to illustrate preferred embodiments of the application and is not intended to limit the scope of the application. The scope of the application is limited only by the claims.

[0029] In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer", "front", "back", etc. indicate the orientation or positional relationship based on the working state of the present application, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third", "fourth" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0030] In order to facilitate the understanding of the embodiments of the present application, the following will be further explained and described with specific examples combined with the accompanying drawings, and each drawing does not constitute a limitation on the embodiments of the present application.

[0031] In a first aspect, the present application provides a negative thermal expansion composite material based on La(Fe, Si) 13 phase, the composite material has the general formula: z(LaFe 13-x-y M y Si x )(100-z)Cu, wherein M can be but is not limited to Mn, Co, preferably M is Mn or Co, for example M is Co; 1.0≤x≤2.5, 0≤y≤2, 55≤z≤100; preferably x=1.2, y=1, 55≤z≤85; more preferably x=1.2, y=1, z=55.

[0032] In the present application, the coefficient of negative thermal expansion (the direction of the coefficient of negative thermal expansion is opposite to that of the coefficient of thermal expansion) of the composite material is different with the copper content, i.e. the composite material has the feature of adjustable coefficient of negative thermal expansion. With the decrease of z value, the copper content gradually increases, and the coefficient of negative thermal expansion of the composite material decreases, the mechanical properties increase, and the deformation behavior changes from brittleness to plasticity. The coefficient of thermal expansion of the composite material is between -20.3 ppm / K and 1.9 ppm / K, the compressive strength is between 70 MPa and 645 MPa, and the ductility is between 0.5% and 4.4%. In particular, when the z value is 55, the coefficient of negative thermal expansion of the composite material approaches 0, realizing zero expansion, and the temperature range is between 280 K and 340 K. At this time, the compressive strength of the composite material is 645 MPa, and the ductility reaches 4.4%. When the z value continues to decrease to 50, the composite material exhibits a positive thermal expansion feature.

[0033] According to the present application, the composite material contains different phases with different copper contents.

[0034] Further, when 1.0≤x≤2.5, 0≤y≤2, and 85<z≤100, the composite material contains La(Fe,Si) 13 , α-Fe, and LaFeSi three phases, and the coefficient of thermal expansion of the composite material is between -20.3 ppm / K and -17.5 ppm / K, the compressive strength is between 70 MPa and 410 MPa, and the ductility is between 0.5% and 1.51%. In particular, when the z value is 100, the mechanical properties of the composite material are the worst, with a compressive strength of only 70 MPa and a ductility of only 0.5%.

[0035] Further, when 1.0≤x≤2.5, 0≤y≤2, and 55<z≤85, the composite material contains La(Fe,Si) 13 , α-Fe, LaFeSi, and LaCu2 four phases, and the coefficient of thermal expansion of the composite material is between -17.6 ppm / K and -2 ppm / K, the compressive strength is between 420 MPa and 640 MPa, and the ductility is between 1.52% and 4.3%.

[0036] Further, when 1.0≤x≤2.5, 0≤y≤2, and z=55, the composite material contains La(Fe,Si) 13 , α-Fe, LaCu2, and LaCuSi four phases. When x=1.2, y=1, and z=55, the coefficient of thermal expansion of the composite material is -1.9 ppm / K, the compressive strength is 645 MPa, and the ductility is 4.4%.

[0037] In an optimal embodiment, x=1.2, y=1, and z=55, and the composite material contains La(Fe,Si)13 , α-Fe, LaCu2 and LaCuSi four phases, at this time the thermal expansion coefficient of the composite material is -1.9ppm / K, the compressive strength is 645MPa, and the ductility is 4.4%.

[0038] According to the application, the addition of Cu element obtains La(Fe,Si) 13 The Cu composite has high compressive strength and ductility, and is a negative thermal expansion composite material with adjustable thermal expansion coefficient. The Cu element can effectively reduce the brittle LaFeSi phase, and introduce new phases such as LaCu2 and LaCuSi which are beneficial to mechanical properties, effectively improve the compressive strength and ductility of the composite material, and make the composite material change from brittle fracture to plastic fracture.

[0039] In the application, the La(Fe,Si) 13 The phase has the characteristics of magnetic volume effect, that is, with the decrease of temperature, it changes from paramagnetic high-temperature phase to ferromagnetic low-temperature phase, the phase transition property is first-order, and the lattice negative expansion accompanying the phase transition is >1%, the LaFeSi phase, LaCu2 phase and LaCuSi phase have positive expansion characteristics, and the thermal expansion coefficients are constant values; by adjusting the phase ratio in the composite material, the thermal expansion coefficient of the composite material can be adjusted from negative to zero. With the increase of α-Fe, LaCu2 and LaCuSi, the comprehensive mechanical properties of the composite material are greatly improved.

[0040] In a second aspect, a preparation method of the negative thermal expansion composite material based on La(Fe,Si) 13 phases in the first aspect is provided, and the method comprises:

[0041] Step 1, mixing and smelting metal elements to obtain a cast alloy ingot;

[0042] Step 2, annealing the cast alloy ingot to obtain a crude product;

[0043] Step 3, quenching the crude product to obtain the composite material.

[0044] The preparation method of the composite material is described below.

[0045] Step 1, mixing and smelting metal elements to obtain a cast alloy ingot.

[0046] In step 1, the addition of the metal elements conforms to the general formula: z(LaFe 13-x-y M y Si x)(100-z)Cu, wherein M can be but is not limited to Mn, Co, preferably M is Mn or Co, for example M is Co; 1.0≤x≤2.5, 0≤y≤2, 55≤z≤100; preferably x=1.2, y=1, 55≤z≤85; more preferably x=1.2, y=1, z=55.

[0047] In step 1, the purity of the metal elements is all above 99.9wt.% to obtain high purity as-cast alloy ingot.

[0048] In step 1, the metal elements are cleaned before melting, preferably the cleaning is performed by the following steps: vacuumizing to 1x10 -3 below, and cleaning 1-2 times with inert gas.

[0049] The inert gas can be argon or helium. The purity of the inert gas is above 99.9wt.%.

[0050] In step 1, the melting temperature is 1500-2500℃, preferably 1800-2200℃, for example 2000℃.

[0051] In step 1, the melting time is 2-3min, preferably 2min.

[0052] In step 1, the melting is performed with inert gas as protective gas to avoid oxidation of the alloy during melting.

[0053] Further, the inert gas is argon or helium; the purity of the inert gas is above 99.9wt.%.

[0054] Preferably, the inert gas used for melting is the same as that used for cleaning the metal elements, for example, both are argon.

[0055] In step 1, the inert gas is 1atm.

[0056] According to the present application, the melting is preferably performed 1-5 times, preferably 2-5 times, for example 5 times, i.e. the metal elements are melted at the melting temperature for the corresponding time, which is referred to as one melting. The multiple melting ensures uniform alloy composition.

[0057] In step 1, the cleaning and melting of the metal elements are preferably performed in an electric arc furnace. For example, the metal elements are placed in the electric arc furnace, vacuumized to 1x10 -3 below, and cleaned 1-2 times with inert gas; then the inert gas is filled into the furnace cavity to about 1atm, the melting is started by starting the arc, and the melting is performed again after the arc is started, and the total melting is performed 1-5 times.

[0058] Step 2: Anneal the cast alloy ingot to obtain a rough product.

[0059] In step 2, the annealing process includes: [the process is carried out under a vacuum degree less than 1×10⁻⁶]. -3 Under the conditions of Pa, anneal at 1000-1100℃ for 2-10 days.

[0060] The main phase composition of the resulting cast alloy ingot is Fe and LaFeSi. During the heat treatment process, the two phases undergo a peritectic reaction to form La(Fe,Si). 13 Prolonged heat treatment helps the peritectic reaction to proceed completely, but it will increase the preparation cycle. Annealing for 2 to 10 days is more appropriate.

[0061] Furthermore, the annealing process includes: [the process is carried out] under a vacuum degree less than 1 × 10⁻⁶. -3 Under the condition of Pa, anneal at 1010-1090℃ for 2-10 days.

[0062] For example, the annealing process includes: [the process is carried out] under a vacuum degree less than 1 × 10⁻⁶. -3 Under the condition of Pa, it was annealed at 1050℃ for 5 days.

[0063] Step 3: Quench the crude product to obtain the composite material.

[0064] In step 3, in order to obtain La(Fe, Si) 13 Metastable phases require the alloy to be rapidly cooled from its phase region temperature to room temperature, i.e., quenching. To ensure the cooling rate, the quenching process uses an ice-water mixture or liquid nitrogen as the medium.

[0065] According to the present invention, La(Fe,Si) exhibits a first-order magnetoelastic phase transition. 13 The magnetocaloric effect of the negative thermal expansion of the alloy originates from the magnetic volume effect driven by the thermal and magnetic fields, respectively. Studies have found that in La(Fe,Si)... 13 The alloy contains NaZn 13 The structure, with space group Fm-3c, exhibits a cell volume change of up to 1% during the phase transition, accompanied by a metamagnetic transition from a paramagnetic state to a itinerant ferromagnetic state. Compared to most magnetically negative thermal expansion materials, La(Fe,Si)... 13 The negative thermal expansion of the base alloy is isotropic; however, due to the low strength of the metallic bonds and the large volume change accompanying the phase transformation, the alloy has poor mechanical properties and will fracture after several phase transformations. This invention provides z(LaFe) 13-x-y M y Si x The mechanical properties of the (100-z)Cu composite material are significantly improved, and it also has zero expansion effect and good mechanical properties.

[0066] Examples:

[0067] The present application is further described by the following specific examples, which are merely exemplary and do not limit the scope of the present application.

[0068] Example 1

[0069] According to the chemical formula 100 (LaFe 10.8 CoSi 1.2 ) 15 Cu, respectively, weigh 1.64210 g of La with a purity of 99.9%, 7.13022 g of Fe with a purity of 99.95%, 0.69669 g of Co with a purity of 99.99%, 0.39842 g of Si with a purity of 99.999%, and 0.1325 g of Cu with a purity of 99.99%, at this time z (LaFe 13-x-y M y Si x ) 15 Cu, M is Co, x = 1.2, y = 1, z = 100; mix the weighed La, Fe, Co and Si and put them into an electric arc furnace, vacuumize to 3 x 10 -3 Pa, wash with argon gas for 2 times, then electric arc start at 1 atmosphere, 99.996wt% purity argon gas protection, smelt at 2000°C for 2 min, at this time re-arc start smelt, total smelt for 5 times, after smelt is finished, cool to room temperature to obtain as-cast alloy ingot;

[0070] Seal the obtained as-cast alloy ingot in a quartz tube with a vacuum degree of 1 x 10 -4 Pa, anneal at 1050°C for 5 days to obtain a crude product, at this time immediately put the quartz tube into liquid nitrogen to break it, obtain composite material 100 (LaFe 10.8 CoSi 1.2 ) 15 Cu.

[0071] Example 2

[0072] According to the chemical formula 100 (LaFe 10.8 CoSi 1.2 ) 15 Cu, respectively, weigh 1.64210 g of La with a purity of 99.9%, 7.13022 g of Fe with a purity of 99.95%, 0.69669 g of Co with a purity of 99.99%, 0.39842 g of Si with a purity of 99.999%, and 0.1325 g of Cu with a purity of 99.99%, at this time z (LaFe 13-x-y M y Si xM is Co, x = 1.2, y = 1, and z = 85; the weighed La, Fe, Co, Si, and Cu are mixed and put into an arc furnace, vacuumized to 3 x 10 -3 Pa, then arc struck at 1 atm, 99.996 wt% purity argon protection, melted at 2000°C for 2 min, then arc struck again for melting, total 3 times of melting, after the melting is finished, cooled to room temperature to obtain a cast alloy ingot;

[0073] The obtained cast alloy ingot is wrapped with a metal tantalum foil and sealed in a quartz tube with a vacuum of 1 x 10 -4 Pa, annealed at 1050°C for 5 days to obtain a crude product, then the quartz tube is immediately put into liquid nitrogen and broken to obtain a composite material 100(LaFe 10.8 CoSi 1.2 ).

[0074] Example 3

[0075] According to the chemical formula 75(LaFe 10.8 CoSi 1.2 ), 1.62297 g of La with a purity of 99.9%, 7.04718 g of Fe with a purity of 99.95%, 0.68858 g of Co with a purity of 99.99%, 0.39378 g of Si with a purity of 99.999%, and 0.24749 g of Cu with a purity of 99.99% are weighed, then z(LaFe 13-x-y M y Si x ) (100-z) Cu, M is Co, x = 1.2, y = 1, and z = 75; the weighed La, Fe, Co, Si, and Cu are mixed and put into an arc furnace, vacuumized to 3 x 10 -3 Pa, then arc struck at 1 atm, 99.996 wt% purity argon protection, melted at 2000°C for 2 min, then arc struck again for melting, total 3 times of melting, after the melting is finished, cooled to room temperature to obtain a cast alloy ingot;

[0076] The obtained cast alloy ingot is wrapped with a metal tantalum foil and sealed in a quartz tube with a vacuum of 1 x 10 -4 Pa, annealed at 1050°C for 5 days to obtain a crude product, then the quartz tube is immediately put into liquid nitrogen and broken to obtain a composite material 100(LaFe 10.8 CoSi 1.2 ).

[0077] Example 4

[0078] According to the chemical formula 65(LaFe10.8 CoSi 1.2 )35Cu respectively 1.59863 g of La with purity of 99.9%, 6.94146 g of Fe with purity of 99.95%, 0.67825 g of Co with purity of 99.99%, 0.38787 g of Si with purity of 99.999% and 0.39379 g of Cu with purity of 99.99%, at this time z(LaFe 13-x-y M y Si x )(100-z)Cu, M is Co, x=1.2, y=1, z=65; the weighed La, Fe, Co, Si and Cu are mixed and put into an arc furnace, vacuumized to 3x10 -3 Pa, purged with argon for 2 times, then arc struck under 1 atmosphere, 99.996wt% purity argon protection, smelted at 2000℃ for 2 min, at this time re-arc struck for smelting, total smelting times 3, after smelting, cooled to room temperature to obtain as-cast alloy ingot;

[0079] The obtained as-cast alloy ingot is wrapped with metal tantalum foil and sealed in a quartz tube with vacuum degree of 1x10 -4 Pa, annealed at 1050℃ for 5 days to obtain crude product, at this time the quartz tube is immediately put into liquid nitrogen to break, to obtain composite material 100(LaFe 10.8 CoSi 1.2 ).

[0080] Example 5

[0081] According to chemical formula 55(LaFe 10.8 CoSi 1.2 )45Cu respectively 1.56658 g of La with purity of 99.9%, 6.80231 g of Fe with purity of 99.95%, 0.66465 g of Co with purity of 99.99%, 0.38010 g of Si with purity of 99.999% and 0.58637 g of Cu with purity of 99.99%, at this time z(LaFe 13-x-y M y Si x )(100-z)Cu, M is Co, x=1.2, y=1, z=55; the weighed La, Fe, Co, Si and Cu are mixed and put into an arc furnace, vacuumized to 3x10 -3 Pa, purged with argon for 2 times, then arc struck under 1 atmosphere, 99.996wt% purity argon protection, smelted at 2000℃ for 2 min, at this time re-arc struck for smelting, total smelting times 5, after smelting, cooled to room temperature to obtain as-cast alloy ingot;

[0082] The as-cast alloy ingot is wrapped with a metal tantalum foil and sealed in a quartz tube with a vacuum of 1 x 10 -4 Pa, annealed at 1050°C for 5 days to obtain a crude product. At this time, the quartz tube is immediately placed in liquid nitrogen and broken to obtain the composite material 100(LaFe 10.8 CoSi 1.2 ).

[0083] Example 6

[0084] According to the chemical formula 50(LaFe 10.8 CoSi 1.2 ), 1.54643 g of La with a purity of 99.9%, 6.71481 g of Fe with a purity of 99.95%, 0.65610 g of Co with a purity of 99.99%, 0.37521 g of Si with a purity of 99.999%, and 0.70745 g of Cu with a purity of 99.99% are weighed. At this time, in z(LaFe 13-x-y M y Si x )(100-z)Cu, M is Co, x = 1.2, y = 1, and z = 50. The weighed La, Fe, Co, Si, and Cu are mixed and placed in an arc furnace, vacuumized to 3 x 10 -3 Pa, purged with argon for 2 times, and then arc struck at 1 atm and 99.996wt% argon protection, melted at 2000°C for 2 min. At this time, the arc is struck again for melting. The total melting is 3 times. After the melting is completed, the as-cast alloy ingot is obtained after cooling to room temperature.

[0085] The as-cast alloy ingot is wrapped with a metal tantalum foil and sealed in a quartz tube with a vacuum of 1 x 10 -4 Pa, annealed at 1050°C for 5 days to obtain a crude product. At this time, the quartz tube is immediately placed in liquid nitrogen and broken to obtain the composite material 100(LaFe 10.8 CoSi 1.2 ).

[0086] Experimental Example:

[0087] Experimental Example 1

[0088] The linear expansion of the composite materials prepared in Examples 1 to 6 is measured by a thermal mechanical analyzer (TMA), and the results are shown in FIG. 1. Figure 1As shown in the figure, it can be seen that with the decrease of z value, i.e. the increase of Cu content, the linear expansion decreases, indicating that the negative thermal expansion coefficient decreases. When z = 100, the thermal expansion coefficient is -20.3 ppm / K, when z = 85, the thermal expansion coefficient is -17.6 ppm / K, when z = 75, the thermal expansion coefficient is -9.3 ppm / K, when z = 65, the thermal expansion coefficient is -7.8 ppm / K, when z = 55, the thermal expansion coefficient is -1.9 ppm / K, and when z = 50, the obtained composite material has a positive thermal expansion characteristic, and the thermal expansion coefficient is 6.7 ppm / K.

[0089] Experimental Example 2

[0090] The compression curves of the composite materials prepared in Examples 1 to 6 were tested by an electronic universal testing machine (AGS-X 100KN) produced by Shimadzu Corporation, Japan, to obtain the compressive strength and ductility of the series of samples, and the results are shown in Table 1. Figure 2 As shown in the figure, it can be seen that the compressive strength and ductility of the prepared composite material increase with the increase of Cu content. Without Cu, the compressive strength is only 70 MPa, and the ductility is only 0.5%; when z = 85, the compressive strength of the obtained composite material increases to 420 MPa, and the ductility is 1.52%; when z = 75, the compressive strength of the obtained composite material is 510 MPa, and the ductility is 2.27%; when z = 65, the compressive strength of the obtained composite material is 554 MPa, and the ductility is 3.81%; when z = 55, the compressive strength of the obtained composite material is 645 MPa, and the ductility increases to 4.4%; when z = 50, the compressive strength of the obtained composite material is 655 MPa, and the ductility increases to 6.55%.

[0091] Experimental Example 3

[0092] The X-ray diffraction patterns of the composite materials prepared in Examples 1, 2 and 5 at room temperature were obtained by an X-ray diffractometer, and the obtained patterns were fitted and calculated by GSAS software to obtain the composition and phase ratio of the composite materials.

[0093] In Example 1, when z = 100, the XRD of the composite material is shown in Figure 3(a), and it can be seen that it contains three phases, i.e. La(Fe, Si) 13 , α-Fe and LaFeSi. When z = 85, the XRD of the composite material is shown in Figure 3(b), and it can be seen that a new LaCu2 phase appears, and at this time, there are four phases of La(Fe, Si) 13 , α-Fe, LaFeSi and LaCu2. When z = 55, the XRD of the composite material is shown in Figure 3(c), and a new LaCuSi phase appears in the composite material, and at this time, there are four phases of La(Fe, Si) 13La(Fe, Si), α-Fe, LaFeSi and LaCu2 four phases; the volume fractions of La(Fe, Si), α-Fe, LaFeSi and LaCu2 are 79.495, 16.9, 1.75, 1.47 respectively; Fig. 4(c) shows the backscattering spectrum of the composite material prepared in Example 5 (z = 55), which can be seen that it contains La(Fe, Si), α-Fe, LaCu2 and LaCuSi four phases, the volume fractions of La(Fe, Si), α-Fe, LaCu2 and LaCuSi are 62.044, 20.343, 12.01, 3.5126 respectively.

[0094] Experimental Example 4

[0095] Fig. 4(a) shows the backscattering spectrum of the composite material prepared in Example 1 (z = 100), which can be seen that it contains La(Fe, Si), α-Fe and LaFeSi three phases; Fig. 4(b) shows the backscattering spectrum of the composite material prepared in Example 2 (z = 85), which can be seen that it contains La(Fe, Si), α-Fe, LaFeSi and LaCu2 four phases; Fig. 4(c) shows the backscattering spectrum of the composite material prepared in Example 5 (z = 55), which can be seen that it contains La(Fe, Si), α-Fe, LaCu2 and LaCuSi four phases. 13 13 13 13 13 13

[0096] The above detailed description of the present application is combined with the preferred embodiments and exemplary examples. However, it is declared that these specific embodiments are only illustrative explanations of the present application, and do not constitute any limitation on the protection scope of the present application. Various improvements, equivalent replacements or modifications can be made to the technical content and embodiments of the present application without departing from the spirit and protection scope of the present application, which all fall within the protection scope of the present application. The protection scope of the present application is subject to the appended claims.​​​​​​

Claims

1. A composite material based on La(Fe,Si) 13 phases with negative thermal expansion, characterized in that, The composite material has the general formula: z(LaFe 13-x-y M y Si x )(100-z)Cu, where M can be, but is not limited to, Mn or Co, 1.0≤x≤2.5, 0≤y≤2, 55≤z≤100.

2. The composite material of claim 1, wherein, Preferably, the thermal expansion coefficient of the composite material is between -20.3 ppm / K and -1.9 ppm / K.

3. The composite material of claim 1, wherein, The compressive strength of the composite material is 70-645 MPa.

4. The composite material of claim 1, wherein, The ductility of the composite material is 0.5-4.4%.

5. The composite material of claim 1, wherein, When 1.0≤x≤2.5, 0≤y≤2, 85<z≤100, the composite material contains La(Fe, Si), α-Fe and LaFeSi three phases. 13 , α-Fe and LaFeSi three phases.

6. The composite material of claim 1, wherein, When 1.0≤x≤2.5, 0≤y≤2, 55<z≤85, the composite material contains La(Fe,Si) 13 , α-Fe, LaFeSi and LaCu2 four phases.

7. The composite material of claim 1, wherein, When 1.0≤x≤2.5, 0≤y≤2, z=55, the composite contains La(Fe,Si), α-Fe, LaCu2 and LaCuSi four phases. 13 , α-Fe, LaCu2 and LaCuSi four phases.

8. A method of making the composite material of any one of claims 1 to 7, characterized in that, The method comprises: Step 1: mixing and smelting metal elements to obtain a cast alloy ingot; Step 2: annealing the cast alloy ingot to obtain a crude product; Step 3: quenching the crude product to obtain the composite material.

9. The method of claim 8, wherein, In step 1, the addition of the elemental metal conforms to the general formula: z(LaFe 13-x-y M y Si x )(100-z)Cu, where M can be, but is not limited to, Mn or Co.

10. The method of claim 9, wherein, 1.0≤x≤2.5, 0≤y≤2, 50≤z≤100.

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