Copper-nickel-tin-silicon alloy and preparation method and application thereof
阅读说明：本技术 一种铜镍锡硅合金及其制备方法和应用 (Copper-nickel-tin-silicon alloy and preparation method and application thereof ) 是由 王鹏飞 王玉帅 梁转琴 原霞 张恺 杨伟 于 2021-07-27 设计创作，主要内容包括：本发明提供了一种铜镍锡硅合金及其制备方法,属于合金技术领域。本发明提供的铜镍锡硅合金,化学组成包括6wt％Ni,6wt％Sn,0.15～1wt％Si和余量铜,物相组成有铜基体、γ-Ni-(5)Si-(2)初生相、DO-(22)型和L1-(2)型析出相。本发明在Cu-6Ni-6Sn合金中添加0.15～1wt％的Si,可在组织中引入γ-Ni-(5)Si-(2)初生相作为合金凝固过程的形核质点以达到细化晶粒或枝晶的目的,以此改善合金在凝固组织的严重偏析现象。同时,经过固溶处理之后初生相依然存在于合金中,可有效抑制合金在时效处理过程中不连续沉淀γ相的产生,也可避免时效处理过程中晶粒的异常长大,从而提高铜镍锡硅合金的力学性能和耐磨性能。(The invention provides a copper-nickel-tin-silicon alloy and a preparation method thereof, belonging to the technical field of alloys. The copper-nickel-tin-silicon alloy provided by the invention comprises 6 wt% of Ni, 6 wt% of Sn, 0.15-1 wt% of Si and the balance of copper in chemical composition, and a phase composition comprises a copper matrix and gamma-Ni 5 Si 2 Primary phase, DO 22 Type sum L1 2 And (4) forming a precipitated phase. According to the invention, 0.15-1 wt% of Si is added into Cu-6Ni-6Sn alloy, and gamma-Ni can be introduced into the structure 5 Si 2 The primary phase is used as nucleation mass point in the alloy solidification process to achieve the purpose of refining grains or dendrites, so that the serious segregation phenomenon of the alloy in a solidification structure is improved. Meanwhile, the primary phase still exists in the alloy after the solution treatment,can effectively inhibit the generation of discontinuous precipitation gamma phase in the aging treatment process of the alloy and also can avoid the abnormal growth of crystal grains in the aging treatment process, thereby improving the mechanical property and the wear resistance of the copper-nickel-tin-silicon alloy.)
1. The copper-nickel-tin-silicon alloy is characterized by comprising the following chemical components of 6 wt% of Ni, 6 wt% of Sn, 0.15-1 wt% of Si and the balance of copper;
the copper-nickel-tin-silicon alloy has gamma-Ni5Si2Primary phase, DO22Precipitated phase and L12And (4) forming a precipitated phase.
2. The method for preparing the copper-nickel-tin-silicon alloy according to claim 1, comprising the steps of:
smelting an alloy raw material to obtain an alloy liquid, and pouring the alloy liquid to obtain an as-cast alloy;
sequentially carrying out hot rolling and solution treatment on the as-cast alloy to obtain a solution alloy; the temperature of the solution treatment is 725-875 ℃;
sequentially carrying out cold rolling and aging treatment on the solid solution alloy to obtain a copper-nickel-tin-silicon alloy; the temperature of the aging treatment is 250-450 ℃.
3. The method according to claim 2, wherein the temperature of the molten alloy at the time of casting is 1200 to 1250 ℃.
4. The method according to claim 2, wherein the hot rolling temperature is 800 to 900 ℃ and the total strain amount is 50 to 80%.
5. The method according to claim 2, wherein the holding time of the solution treatment is 4 to 8 hours.
6. The method according to claim 2, wherein the cold rolling is performed at room temperature and the total deformation is 30 to 50%.
7. The preparation method according to claim 2, wherein the aging treatment is carried out for 0.5-4 hours.
8. The method of claim 2, 5 or 7, wherein the chemical composition of the alloy feedstock, the solution treatment temperature and the aging treatment temperature are calculated by Pandat software simulation.
9. The copper nickel tin silicon alloy of claim 1 or the copper nickel tin silicon alloy obtained by the preparation method of any one of claims 2 to 8 is applied to high-end sliding bearings, aerospace, rail transit, heavy-duty machinery or ocean engineering.
Technical Field
The invention relates to the technical field of alloys, in particular to a copper-nickel-tin-silicon alloy and a preparation method and application thereof.
Background
The copper-nickel-tin alloy is a novel copper alloy, has the advantages of high strength, high elasticity, wear resistance, corrosion resistance and the like, and has very wide application prospect in the fields of aerospace, rail transit, heavy-duty machinery, ocean engineering and the like. However, the preparation of the copper-nickel-tin alloy has two technical problems, namely, the segregation of tin element in the solidification process generates a large amount of tin-rich phase; secondly, a large amount of discontinuous precipitation gamma-phase is generated in the heat treatment process, which will damage the mechanical properties of the alloy. The two problems can be solved to a certain extent by adding alloying elements and combining a reasonable heat treatment process. For example, the prior art "study of solution treatment Process and Structure Properties of Cu-9.5Ni-2.3Sn-0.5Si alloy" (see the study of solution treatment Process and Structure Properties of alloy Cu-9.5Ni-2.3Sn-0.5Si, Lidong, Liao Yumin, Denli. [ J ] in Liu Donghui]Heat treatment 2014,29(04): 29-32) discloses a Cu-9.5Ni-2.3Sn-0.5Si alloy in which Ni is formed2Si、Ni31Si12And occupied nucleation sites, the alloy had a vickers hardness of 152 HV. However, the above alloys have a low tin content and limited precipitates formed during aging treatment, and therefore the hardness of the alloys is not sufficiently high.
Disclosure of Invention
In view of the above, the present invention aims to provide a copper-nickel-tin-silicon alloy, and a preparation method and an application thereof, and the copper-nickel-tin-silicon alloy provided by the present invention has characteristics of high hardness, high strength, excellent frictional wear performance, and excellent comprehensive mechanical properties.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a copper-nickel-tin-silicon alloy which comprises the chemical compositions of 6 wt% of Ni, 6 wt% of Sn, 0.15-1 wt% of Si and the balance of copper;
the above-mentionedThe copper-nickel-tin-silicon alloy has gamma-Ni5Si2Primary phase, DO22Precipitated phase and L12And (4) forming a precipitated phase.
The invention provides a preparation method of the copper-nickel-tin-silicon alloy in the technical scheme, which comprises the following steps:
smelting an alloy raw material to obtain an alloy liquid, and pouring the alloy liquid to obtain an as-cast alloy;
sequentially carrying out hot rolling and solution treatment on the as-cast alloy to obtain a solution alloy; the temperature of the solution treatment is 725-875 ℃;
sequentially carrying out cold rolling and aging treatment on the solid solution alloy to obtain a copper-nickel-tin-silicon alloy; the temperature of the aging treatment is 250-450 ℃.
Preferably, the temperature of the alloy liquid during casting is 1200-1250 ℃.
Preferably, the hot rolling temperature is 800-900 ℃, and the total deformation is 50-80%.
Preferably, the heat preservation time of the solution treatment is 4-8 h.
Preferably, the cold rolling temperature is room temperature, and the total deformation is 30-50%.
Preferably, the heat preservation time of the aging treatment is 0.5-4 h.
Preferably, the chemical composition of the alloy raw material, the temperature of the solution treatment and the temperature of the aging treatment are obtained by simulation calculation of a Pandat software.
The invention provides the application of the copper-nickel-tin-silicon alloy in the technical scheme or the copper-nickel-tin-silicon alloy prepared by the preparation method in the technical scheme in high-end sliding bearings, aerospace, rail transit, heavy-duty machinery or ocean engineering.
The invention provides a copper-nickel-tin-silicon alloy which comprises the chemical compositions of 6 wt% of Ni, 6 wt% of Sn, 0.15-1 wt% of Si and the balance of copper; the copper-nickel-tin-silicon alloy has gamma-Ni5Si2Primary phase, DO22Precipitated phase and L12And (4) forming a precipitated phase. In the invention, copper is used as a matrix in the copper-nickel-tin-silicon alloy, nickel can form an infinite solid solution with copper,the tin also has certain solid solubility in copper and can reduce the solubility of nickel in copper, and when the content of tin exceeds 4%, the alloy is a typical spinodal decomposition reinforced alloy, and the spinodal decomposition can be carried out by aging treatment to simultaneously generate DO22Precipitated phase and L12A type precipitated phase and a discontinuous precipitated gamma phase, the solid solubility of silicon in copper is extremely low, and when the silicon is added into the copper-nickel-tin ternary alloy, gamma-Ni is mainly used5Si2The primary phase exists in a form, so that the segregation of tin element in the alloy solidification process and the large generation of discontinuous precipitation gamma phase in the heat treatment process can be inhibited. The structure of the alloy subjected to final aging treatment in the copper-nickel-tin-silicon alloy provided by the invention simultaneously has relatively coarse gamma-Ni5Si2Nascent phase and fine DO22Type sum L12The type precipitated phase is distributed on the matrix, and the comprehensive performance of the alloy is obviously improved. As shown in the results of the examples, the tensile strength of the copper-nickel-tin-silicon alloy provided by the invention is 783-967 MPa, the yield strength is 712-912 MPa, the elongation after fracture is 10-14%, the hardness is 241-327 HB, and the friction coefficient of the copper-nickel-tin-silicon alloy to bearing steel under the boundary lubrication condition is 0.12-0.15.
The invention provides a preparation method of the copper-nickel-tin-silicon alloy in the technical scheme. Aiming at the problem of massive generation of segregation and discontinuous precipitation gamma phase in the preparation of a typical copper-nickel-tin alloy, the preparation method provided by the invention adds 0.15-1% of alloying element Si in the Cu-6Ni-6Sn alloy through component design and reasonably controls the subsequent heat treatment temperature and time so as to solve the common problem in the preparation of the copper-nickel-tin alloy, and particularly avoids the remelting of the copper-nickel-tin-silicon alloy in the process of solution treatment through component design and the control of the temperature of solution treatment; by the action of the primary phase and the control of the temperature of the aging treatment, a large amount of discontinuous precipitation phases are avoided, so that the mechanical property and the wear resistance of the copper-nickel-tin alloy are improved; moreover, the preparation method provided by the invention is simple to operate, low in cost, high in efficiency and suitable for industrial production.
Drawings
FIG. 1 is a simulated phase diagram of a Cu-6Ni-6Sn-xSi alloy;
FIG. 2 is a gold phase diagram of an as-cast Cu-6Ni-6Sn-0.6Si alloy prepared in example 1;
FIG. 3 is an SEM photograph and a chart of results of energy spectrum analysis of an as-cast Cu-6Ni-6Sn-0.6Si alloy prepared in example 1, wherein (a) is the SEM photograph, A is a black phase, B is a white phase, C is a matrix phase, (B) is the results of energy spectrum analysis of the black phase, (C) is the results of energy spectrum analysis of the white phase, and (d) is the results of energy spectrum analysis of the matrix phase;
FIG. 4 is a transmission electron micrograph, a selected area electron diffraction pattern, a high resolution transmission electron micrograph, and a Fourier transform of the white phase B of FIG. 2, wherein (a) is a transmission bright field micrograph, (B) is a selected area electron diffraction pattern, (c) is a high resolution transmission electron micrograph, and (d) is a Fourier transform micrograph;
FIG. 5 is an SEM photograph and results of energy spectrum analysis of a solid-solution Cu-6Ni-6Sn-0.6Si alloy prepared in example 1, wherein (a) is the SEM photograph, (b) is the results of energy spectrum analysis of EDS Spot1, (c) is the results of energy spectrum analysis of EDS Spot2, and (d) is the results of energy spectrum analysis of EDS Spot 3;
FIG. 6 is a transmission electron micrograph, a selected area electron diffraction pattern, a high resolution transmission electron micrograph, and a Fourier transform of EDS Spot1 of FIG. 4, wherein (a) is a transmission bright field map, (b) is a selected area electron diffraction pattern, (c) is a high resolution transmission electron micrograph, and (d) is a Fourier transform map;
FIG. 7 is a gold phase diagram of the as-aged Cu-6Ni-6Sn-0.6Si alloy prepared in example 1;
FIG. 8 is a TEM image of the as-aged Cu-6Ni-6Sn-0.6Si alloy prepared in example 1, wherein (a) is a transmission bright field image, (b) is a selected area electron diffraction image, (c) is a high-resolution transmission electron micrograph, and (d) is a Fourier transform image;
FIG. 9 is a gold phase diagram of an as-cast Cu-6Ni-6Sn alloy prepared in comparative example 1;
FIG. 10 is a gold phase diagram of an aged Cu-6Ni-6Sn alloy prepared in comparative example 1;
FIG. 11 is a transmission bright field image of the as-aged Cu-6Ni-6Sn alloy prepared in comparative example 1;
FIG. 12 is SEM images of fracture morphology of tensile specimens of the Cu-6Ni-6Sn-0.6Si alloy prepared in example 1 and the Cu-6Ni-6Sn alloy prepared in comparative example 1;
FIG. 13 is a gold phase diagram of the Cu-6Ni-6Sn-0.6Si alloy prepared in comparative example 5 after solution treatment;
FIG. 14 is a diagram of the gold phase of the Cu-6Ni-6Sn-0.6Si alloy prepared in comparative example 7 after aging treatment;
FIG. 15 is a tensile curve of the Cu-6Ni-6Sn-0.6Si alloy prepared in example 1 and the Cu-6Ni-6Sn alloy prepared in comparative example 1;
FIG. 16 shows the results of three sets of frictional wear tests on the Cu-6Ni-6Sn-0.6Si alloy prepared in example 1;
FIG. 17 shows the results of three sets of frictional wear tests on the Cu-6Ni-6Sn alloy prepared in comparative example 1.
Detailed Description
The invention provides a copper-nickel-tin-silicon alloy (marked as Cu-6Ni-6Sn- (0.15-1) Si), which comprises the chemical compositions of 6 wt% of Ni, 6 wt% of Sn, 0.15-1 wt% of Si and the balance of copper; the copper-nickel-tin-silicon alloy has gamma-Ni5Si2Primary phase, DO22Precipitated phase and L12And (4) forming a precipitated phase. In the invention, the content of Si in the copper-nickel-tin-silicon alloy is preferably 0.2 to 0.9 wt%, more preferably 0.3 to 0.8 wt%, even more preferably 0.4 to 0.7 wt%, and most preferably 0.5 to 0.6 wt%.
The invention provides a preparation method of the copper-nickel-tin-silicon alloy in the technical scheme, which comprises the following steps:
smelting an alloy raw material to obtain an alloy liquid, and pouring the alloy liquid to obtain an as-cast alloy;
sequentially carrying out hot rolling and solution treatment on the as-cast alloy to obtain a solution alloy; the temperature of the solution treatment is 725-875 ℃;
sequentially carrying out cold rolling and aging treatment on the solid solution alloy to obtain a copper-nickel-tin-silicon alloy; the temperature of the aging treatment is 250-450 ℃.
In the present invention, all the raw material components are commercially available products well known to those skilled in the art unless otherwise specified.
The method comprises the steps of smelting alloy raw materials to obtain alloy liquid, and pouring the alloy liquid to obtain the as-cast alloy.
In the invention, the raw materials of the alloy are preferably electrolytic copper, nickel, tin and silicon, the purity of the electrolytic copper is preferably equal to or more than 99.97%, the purity of the nickel is preferably equal to or more than 99.8%, the purity of the tin is preferably equal to or more than 99.9%, and the purity of the silicon is preferably equal to or more than 99.99%; in the invention, the dosage ratio of electrolytic copper, nickel, tin and silicon in the alloy raw material meets the chemical composition of the copper-nickel-tin-silicon alloy in the technical scheme. In the invention, alloy raw materials are smelted, preferably electrolytic copper, nickel and tin are smelted to obtain a melt, and when the temperature of the melt is kept at 1250-1350 ℃, silicon is added for heat preservation smelting to obtain alloy liquid; the melting temperature is preferably 1100-1400 ℃, and more preferably 1200-1300 ℃; the temperature of the heat preservation smelting is preferably 1250-1350 ℃, and more preferably 1300 ℃; the time for heat preservation smelting is preferably 5-15 min, and more preferably 10 min. In the present invention, the melting is preferably performed in a graphite crucible of a medium frequency induction furnace.
In the invention, the temperature of the alloy liquid during casting is preferably 1200-1250 ℃, more preferably 1210-1240 ℃, and further preferably 1220-1230 ℃. In the invention, the mould adopted for pouring is preferably a preheated steel mould, and the temperature of the preheated steel mould is preferably 200-400 ℃, and more preferably 300 ℃.
After the casting, the invention preferably also comprises the steps of cooling to room temperature, demoulding and surface cutting to obtain as-cast alloy; the cooling and demolding manner is not particularly limited in the present invention, and may be any manner known to those skilled in the art. The surface cutting is not particularly limited, and the shrinkage cavity and the scale on the surface of the as-cast alloy can be removed. In the present invention, γ -Ni is present in the structure of the as-cast alloy5Si2A primary phase.
In the invention, the chemical composition of the alloy raw material (i.e. the chemical composition of the copper-nickel-tin-silicon alloy) is preferably determined by using Pandat software, simulation phase diagram calculation of the copper-nickel-tin-silicon alloy (marked as Cu-6Ni-6Sn-xSi, wherein x is the mass percentage content of Si in the copper-nickel-tin-silicon alloy) is carried out by using the Pandat software, the phase composition in the solidification process of the Cu-6Ni-6Sn-xSi alloy is predicted according to the result of the simulation phase diagram calculation, and whether a primary phase is generated in the phase composition or not is determined and the type of the primary phase is predicted; the method comprises the following specific steps: opening the Pandat software, selecting four elements of Cu, Ni, Sn and Si, setting the mass percent of Ni to be 6%, the mass percent of Sn to be 6%, Si to be a variable and the balance to be Cu; setting the calculation temperature to be 300-1200 ℃; calculating a phase diagram and outputting a result to obtain a simulated phase diagram result of the Cu-6Ni-6Sn-xSi alloy; according to the simulated phase diagram result, the Si content and the phase composition of the Cu-6Ni-6Sn-xSi alloy in the solidification process are determined, only the primary phase cannot be eliminated through solution treatment, and further the generation of a large amount of discontinuous precipitation gamma phase can be inhibited in the subsequent aging treatment process. Solution and aging temperatures were determined from simulated phase diagrams showing phase transitions (solidus, liquidus and other phase boundaries) in combination with experimental characterization.
After the as-cast alloy is obtained, the as-cast alloy is subjected to hot rolling and solution treatment in sequence to obtain the solid solution alloy. In the invention, the hot rolling temperature is preferably 725-875 ℃, more preferably 750-850 ℃, and further preferably 800 ℃; the total deformation amount of the hot rolling is preferably 50 to 80%, more preferably 55 to 75%, and further preferably 60 to 70%. In the invention, the temperature of the solution treatment is 725-875 ℃, preferably 750-850 ℃, and more preferably 800 ℃; the heat preservation time of the solution treatment is preferably 4-8 h, more preferably 5-7 h, and further preferably 6 h. In the present invention, after hot rolling and solution treatment, γ -Ni5Si2The distribution state and size of primary phase are changed, specifically gamma-Ni5Si2The size of the primary phase is smaller, the appearance tends to be ellipsoidal, the distribution is more dispersive, and the crystal boundary positions are more.
After the solid solution alloy is obtained, the invention sequentially carries out cold rolling and aging treatment on the solid solution alloy to obtain the copper-nickel-tin-silicon alloy. In the invention, the temperature of the cold rolling is preferably room temperature (20-25 ℃); the total deformation amount of the cold rolling is preferably 30-50%, and more preferably 30-50%35 to 45%, and more preferably 40%. In the invention, the temperature of the aging treatment is 250-450 ℃, preferably 300-400 ℃, and more preferably 350 ℃; the heat preservation time of the aging treatment is preferably 0.5-4 h, more preferably 1-3 h, and further preferably 2 h. In the invention, fine precipitation phases which are distributed in a dispersed way are generated in the alloy after the aging treatment, and the primary phase gamma-Ni is used as the primary phase5Si2The effect of (3) is to inhibit the generation of discontinuous precipitation phase in the alloy, thereby improving the mechanical property and the wear resistance of the copper-nickel-tin-silicon alloy.
For copper-nickel-tin-silicon alloys, the composition design and structure control are the key to determine the performance, and the practical use of such alloys is directly influenced. Designing components: the method comprises the steps of designing the components of the copper-nickel-tin-silicon alloy and preparing the Cu-6Ni6Sn-xSi alloy by a method combining simulation calculation and experimental representation, specifically, adopting professional thermodynamics and kinetics calculation software Pandat software to calculate a simulated phase diagram of the Cu-6Ni6Sn-xSi alloy, predicting the phase composition of the alloy and whether a primary phase is generated or not in the solidification process of the alloy according to the calculation result, and predicting the type of the primary phase; the structure of the Cu-6Ni6Sn-xSi alloy is analyzed by experimental characterization means such as SEM, EPMA, TEM and the like, and the phase composition and the type of a primary phase of the alloy are determined. The tissue regulation mechanism is as follows: the phase composition and the phase transformation mechanism of the alloy at different temperatures are predicted by utilizing simulation calculation of solid solution and aging treatment of the Cu-6Ni6Sn-xSi alloy, and are verified by experimental means such as SEM, EPMA, TEM and the like, so that the prepared copper-nickel-tin-silicon alloy has excellent mechanical property and frictional wear property. The preparation method provided by the invention is simple and convenient to operate, easy to implement, free of a large number of raw materials and tests, greatly saves time, improves efficiency and reduces the cost of the tests and the materials.
The invention provides the application of the copper-nickel-tin-silicon alloy in the technical scheme or the copper-nickel-tin-silicon alloy prepared by the preparation method in the technical scheme in high-end sliding bearings, aerospace, rail transit, heavy-duty machinery or ocean engineering.
In the invention, the prepared Cu-6Ni-6Sn- (0.15-1) Si alloy can be used as a landing gear in aerospace, a supporting spring in rail transit, a shaft sleeve and a bushing in heavy-duty machinery, a sliding bearing and a shaft sleeve of a marine diesel engine in ocean engineering and a protective sleeve of a drilling rod of an offshore oil drilling platform.
The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The chemical composition design of the copper-nickel-tin-silicon alloy is carried out by utilizing Pandat software, the Pandat software is opened, four elements of Cu, Ni, Sn and Si are selected, the mass percent of Ni is set to be 6%, the mass percent of Sn is set to be 6%, Si is set to be variable, and the balance is Cu; setting the calculation temperature to be 300-1200 ℃; and calculating a phase diagram and outputting the result, wherein the simulated phase diagram result of the Cu-6Ni-6Sn-xSi alloy is shown in figure 1, wherein FCC represents a face-centered cubic structure, and L represents a liquid phase. As can be seen from FIG. 1, when the Si content exceeds 0.15 wt%, γ -Ni is generated in the alloy during solidification5Si2Phase, and the presence of the FCC matrix and L phase, can theoretically illustrate γ -Ni5Si2Is a primary phase and is expected to be eliminated by solution treatment.
The alloy composition was determined from FIG. 1 to be 6 wt% Ni, 6 wt% Sn, 0.6 wt% Si and the balance copper (noted as Cu-6Ni-6Sn-0.6 Si).
Placing electrolytic copper with the purity of 99.97%, nickel with the purity of 99.8% and tin with the purity of 99.9% in a graphite crucible of a medium-frequency induction furnace for melting, adding silicon with the purity of 99.99% when the temperature of the obtained melt is 1250-1350 ℃, preserving heat and melting for 10min at the temperature, and then obtaining alloy liquid with the temperature of 1200-1250 ℃; and pouring the alloy liquid into a steel die preheated to 300 ℃, cooling to room temperature, demoulding, and then performing surface cutting to remove shrinkage cavities and oxide skin to obtain the as-cast alloy.
And (2) carrying out hot rolling on the as-cast alloy at 850 ℃, and then carrying out solution treatment for 6h at 850 ℃ to obtain a solid solution alloy, wherein the total deformation amount of the hot rolling is 50%.
And (3) cold rolling the solid solution alloy at room temperature, and then carrying out aging treatment for 2h at 350 ℃ to obtain the copper-nickel-tin-silicon alloy (marked as Cu-6Ni-6Sn-0.6Si alloy), wherein the total deformation of the cold rolling is 30%.
The gold phase diagram of the as-cast alloy prepared in this example is shown in fig. 2, and it can be seen from fig. 2 that the crystal grains or dendrites of the as-cast alloy are refined, the severe segregation phenomenon of tin element is improved, and a tin-rich phase generated by the segregation of a large amount of tin element does not occur. The SEM image and the energy spectrum analysis result of the as-cast alloy prepared in this example are shown in FIG. 3, in which (a) is the SEM image, A is the black phase, B is the white phase, and C is the matrix phase; (b) the results of the spectral analysis of the black phase, (c) the results of the spectral analysis of the white phase, and (d) the results of the spectral analysis of the matrix phase. The transmission bright field image, the selected area electron diffraction image, the high-resolution transmission electron microscope image and the Fourier transform of the white phase B are shown in FIG. 4, wherein, (a) the transmission bright field image, (B) the selected area electron diffraction image, (c) the high-resolution transmission electron microscope image, and (d) the Fourier transform image. As can be seen from FIGS. 3 to 4, the as-cast alloy has two distinct phases (black phase A and white phase B) distributed on the matrix C; the white phase has high Si content, and the atomic ratio of Ni to Si is close to 5: 2; the content of Sn in the black material phase is high, and the black material phase can be judged to be a Sn-rich phase generated by the segregation of Sn element in the solidification process of the alloy; the matrix has a low content of Si and Sn and is considered to be a single phase FCC solid solution. The white phase can be further confirmed and proved to be a primary phase gamma-Ni by a transmission electron microscope image, selective area electron diffraction, high resolution and Fourier transform images of the white phase5Si2。
The SEM image and the energy spectrum analysis result of the solid solution alloy prepared in this example are shown in fig. 5, in which (a) is the SEM image, and the second phase (EDS Spot1, EDS Spot2, and EDS Spot3) is distributed on the matrix; (b) the result of the energy spectrum analysis of the EDS Spot1, (c) the result of the energy spectrum analysis of the EDS Spot2, and (d) the result of the energy spectrum analysis of the EDS Spot 3. EDS SpFIG. 6 shows a transmission electron micrograph, a selected area electron diffraction micrograph, a high-resolution transmission electron micrograph, and a Fourier transform of ot1, where (a) is a bright field micrograph of the second phase, (b) is a selected area electron diffraction micrograph of the second phase, (c) is a high-resolution transmission electron micrograph, and (d) is a Fourier transform micrograph. As can be seen from FIGS. 5 to 6, other phases (second phases) still exist in the solid solution alloy and are distributed on the matrix; the energy spectrum result shows that the Si content of the phase is high, and the atomic ratio of Ni and Si is close to 5: 2; it is demonstrated by FIG. 6 that the phase remains the same as the gamma-Ni in the as-cast alloy structure5Si2A phase whose morphology has changed only after hot rolling and solution treatment; meanwhile, the tin-rich phase generated by Sn element segregation in the as-cast alloy structure completely disappears, namely completely dissolves in the matrix. Thus, gamma-Ni5Si2The phase is a primary phase that cannot be eliminated by solution treatment. The experimental results are completely consistent with the theoretical simulation calculation by using the Pandat software.
The gold phase diagram of the Cu-6Ni-6Sn-0.6Si alloy prepared in the embodiment is shown in FIG. 7, and it can be seen that no large amount of discontinuous precipitation gamma phase appears and the crystal grains are very fine after the alloy is aged. The transmission electron microscope image, the selected area electron diffraction image, the high-resolution transmission electron microscope image and the Fourier transform image of the Cu-6Ni-6Sn-0.6Si alloy prepared in the embodiment are shown in FIG. 8, wherein (a) is a transmission bright field image, (b) is a selected area electron diffraction image, (c) is a high-resolution transmission electron microscope image, and (d) is a Fourier transform image. As can be seen from FIG. 8, the aging treatment of the Cu-6Ni-6Sn-0.6Si alloy results in the formation of significantly fine precipitated phases, which can be determined to be DO by electron diffraction, high-resolution transmission electron microscopy and Fourier transform22Type sum L12Form, not discontinuously precipitated gamma phase.
Examples 2 to 5
The copper-nickel-tin-silicon alloy was prepared according to the method of example 1, and the preparation conditions of examples 2 to 5 are shown in table 1.
Comparative examples 1 to 7
The copper-nickel-tin-silicon alloy was prepared according to the method of example 1, and the preparation conditions of comparative examples 1 to 7 are shown in table 1.
TABLE 1 preparation conditions of examples 1 to 5 and comparative examples 1 to 7
The gold phase diagram of the as-cast alloy prepared in comparative example 1 is shown in fig. 9, and it can be seen from fig. 9 that the crystal grains or dendrites of the as-cast alloy are relatively coarse and there are a large amount of black tin-rich phases due to the segregation of tin element. The gold phase diagram of the Cu-6Ni-6Sn alloy prepared in comparative example 1 is shown in FIG. 10, and it can be seen from FIG. 10 that a large amount of black discontinuous precipitation gamma-phase appears after the Cu-6Ni-6Sn alloy is subjected to aging treatment
The bright field transmission of the Cu-6Ni-6Sn alloy prepared in the comparative example 1 is shown in FIG. 11, and it can be seen from FIG. 11 that a large amount of discontinuous precipitation gamma-phase appears after the aging treatment of the Cu-6Ni-6Sn alloy without adding silicon, and the mechanical property and the frictional wear property of the alloy are seriously damaged by the discontinuous precipitation gamma-phase.
SEM images of fracture morphology of tensile samples of the Cu-6Ni-6Sn-0.6Si alloy prepared in the example 1 and the Cu-6Ni-6Sn alloy prepared in the comparative example 1 are shown in FIG. 12, and as can be seen from FIG. 12, fracture pits of the Cu-6Ni-6Sn-0.6Si alloy prepared in the example of the invention are smaller and deeper, and the plasticity is further illustrated.
The phase diagram of the alloy in the solution state prepared in the comparative example 5 is shown in FIG. 13, and it can be seen from FIG. 13 that when the temperature of solution treatment is 900 ℃, the Cu-6Ni-6Sn-0.6Si alloy will be remelted, the damage to the alloy is irreversible, and the subsequent aging treatment of the alloy and the performance of the alloy will be seriously affected.
The metallographic graph of the Cu-6Ni-6Sn-0.6Si alloy prepared in comparative example 7 is shown in FIG. 14, and it can be seen from FIG. 14 that a large number of discontinuous precipitated phases are generated at a time-effect treatment temperature of 500 ℃, which results in a significant decrease in mechanical properties of the Cu-6Ni-6Sn-0.6Si alloy.
Test example 1
Mechanical and abrasion resistance testing
Tensile strength, yield strength and elongation after fracture test: room temperature uniaxial tensile test, test method GB/T228.1-2010 metallic material tensile test part 1: room temperature test method.
And (3) hardness testing: the Brinell hardness test at room temperature is carried out according to the GB/T231.1-2009 Brinell hardness test first part of metal materials: test methods.
And (3) testing the friction coefficient: the alloy prepared in the examples 1-5 and the alloy prepared in the comparative examples 1-7 and the bearing steel are subjected to a reciprocating friction and wear test by adopting an SRV-IV fretting friction and wear testing machine and a separating machine, and the specific steps are that 2 mu L of lubricating oil is dropped, pre-grinding is carried out for 30s under the condition that the loading is 50N, and then the loading is added to 150N for a continuous friction test for 90 min.
The mechanical properties and friction properties of the alloys prepared in examples 1 to 5 and comparative examples 1 to 7 were measured and the results are shown in table 2.
TABLE 2 Performance test results of alloys prepared in examples 1 to 5 and comparative examples 1 to 7
As shown in Table 2, the tensile strength of the copper-nickel-tin-silicon alloy prepared by the invention is 783-967 MPa, the yield strength is 712-912 MPa, the elongation after fracture is 10-14%, the hardness is 241-327 HB, and the friction coefficient is 0.12-0.15.
The Cu-6Ni-6Sn-0.6Si alloy prepared in example 1 and the Cu-6Ni-6Sn alloy prepared in comparative example 1 were subjected to room temperature uniaxial tensile tests, and in order to ensure the reliability of the test results, each alloy was subjected to three sets of tensile tests, of which the most representative two sets of comparative tensile curves are shown in FIG. 15, and the average tensile strength, the average yield strength and the average elongation are shown in Table 2. From this, it is understood that the strength and elongation of the Cu-6Ni-6Sn-0.6Si alloy prepared in example 1 are significantly higher than those of the Cu-6Ni-6Sn alloy prepared in comparative example 1.
The Cu-6Ni-6Sn-0.6Si alloy prepared in example 1 and the Cu-6Ni-6Sn alloy prepared in comparative example 1 were subjected to frictional wear tests, and three sets of frictional wear tests were performed for each alloy in order to ensure reliability of the test results, as shown in FIGS. 16 and 17, wherein FIG. 16 is the results of the frictional wear tests for the three sets of Cu-6Ni-6Sn-0.6Si alloy prepared in example 1; FIG. 17 shows the results of three sets of frictional wear tests on Cu-6Ni-6Sn alloy prepared in comparative example 1; the average coefficient of friction is shown in table 2. From this, it is understood that the friction coefficient of the Cu-6Ni-6Sn-0.6Si alloy prepared in example 1 is significantly lower than that of the Cu-6Ni-6Sn alloy prepared in comparative example 1.
Therefore, the Cu-6Ni-6Sn-0.6Si alloy prepared in example 1 has better mechanical properties and frictional wear properties than the Cu-6Ni-6Sn alloy prepared in comparative example 1.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.