CN115821110B - C70350 alloy for establishing ingredient cooperative change relation based on cluster method - Google Patents

Abstract

The invention discloses a C70350 alloy that establishes a synergistic change relationship between components based on a cluster method and a preparation method. One of the C70350 alloys that establishes a synergistic change relationship in components based on the cluster method is characterized by dividing the C70350 alloying elements into matrix Cu elements that enter the cluster formula; Ni-like elements: containing Ni, Co; Si elements; And trace elements that do not enter the cluster formula: including Pb, Fe, Zn, Mn, Mg; the cooperative change relationship of each element in the cluster formula converted into atomic percentage is: 1.05≤Ni/Co≤1.51, 1.66≤(Ni +Co)/Si≤2.89, based on the synergistic change relationship of each element, the number of atoms occupied by Ni, Co, and Si elements in the cluster formula is: 8≤Ni+Co+Si≤16, this The invention discloses a C70350 alloy and preparation method based on a cluster method to establish a synergistic change relationship between components, which can simplify the complex alloying of high-temperature alloys and propose a new alloy design method that can solve the problem of difficult control of existing C70350 copper alloy elements. The problem.

Description

C70350 alloy to establish synergistic change relationship of components based on cluster method

Technical field

The present invention relates to the field of non-ferrous metals, and in particular to the C70350 alloy that establishes a synergistic change relationship between components based on a cluster method.

Background technique

CuNiCoSi alloy is a precipitation-strengthened alloy with copper as the matrix and Ni, Co, and Si as the second phase strengthening elements. Due to its good hot and cold processing properties, better micro-machining and etching properties, and better soldering properties, it has gradually replaced the traditional Fe-Ni series and Cu-Fe-P series alloys and become a new generation of integrated circuits. Lead frame material. However, because alloy properties are sensitive to ingredient ratios and preparation processes, it is difficult to reconcile the strength and conductivity ratios, and the alloy quality is difficult to control.

Generally speaking, the strength of an ideal lead frame material cannot be less than 600MPa, its hardness cannot be less than 130HV, and its conductivity cannot be less than 40% IACS. The current technical standard GB/T5231-2022 "Processing Copper and Copper Alloy Grades and Chemical Compositions" stipulates that the composition range of C70350 copper alloy (Ni+Co) is 2.0-4.5wt.%, and the composition range of Si is 0.5-1.2wt .%; the 2014 version of ASTM copper and copper alloy composition standards stipulates that the composition range of C70350 copper alloy (Ni+Co) is 1.0-3.0wt.%, and the composition range of Si is 0.2-0.8wt.%; in the U.S. UNS standard The composition range of C70350 copper alloy (Ni+Co) is 2.0-4.5wt.%, and the composition range of Si is 0.5-1.2wt.%; the composition range of C70350 copper alloy (Ni+Co) in the German DIN standard is 1.5-3.0 wt.%, the composition range of Si is 0.4-1.5wt.%. The composition points of the above-mentioned C70350 copper alloy fall in different composition intervals, so it is difficult to accurately select the composition of the C70350 copper alloy.

The current GH4169 high-temperature alloy composition standard (GB/T14992-2005) is also limited to the determination of the composition interval of a single element, ignoring the interaction between elements. At the same time, the interval range of various elements is large. The current CuNi ₁ Co ₁ Si The alloy composition standard (DIN) stipulates: The specified element mass percentage of CuNi ₁ Co ₁ Si is: 1.0≤Ni≤2.0, 0.5≤Co≤1.0, 0.4≤Si≤1.5, and the balance of Cu. As shown in Figure 1, the irregularly distributed squares in the figure are from the literature Shaobin Pan, Materials&Design, Volume 209, 109929, November 2021; He Wei, Materials Science&

Engineering A, Volume 814, 141239, May 2021; Jiang Li, Materials, Volume 18, 2855, September 2019; Xiangpeng Xiao, CRYSTALS, Volume 8, Issue 11, Page 435, November 2018 ; Peng Lijun, Rare Metal Materials and Engineering, Issue 6, 2019, Pages 1969-1974; Zhuan Zhao, Journal of Alloys and Compounds, Volume 797, Pages 1327-1337, C70350 copper alloy reported in mid-August 2019, from Starting from the starting point (Ni, Co), the slope ending at the Si content is the ratio line of (Ni+Co)/Si=2. The effect of Ni/Co ratio on the properties of C70350 alloy was studied. Although the single element composition range is in the industrial Within the scope specified by the standard, however, there are significant differences in the properties of alloys with different Ni/Co ratios. Inaccurate element ranges lead to a decrease in alloy properties. When the Ni/Co ratio is 5, the tensile strength of the alloy is about 618N/mm ² ; the Ni/Co ratio is At 2 o'clock, the tensile strength of the alloy can reach about 854N/ ^mm2 . The range of the parallelogram is the CuNi ₁ Co ₁ Si industry standard composition range. The actual C70350 copper alloy composition reported in the existing literature is mainly concentrated in the narrow range in the figure (represented by squares), while the industry standard gives an overly broad range. The composition range shows that the fixed element composition range deviates greatly from the alloy composition currently studied. This shows that a wide range of individual elements or failure to consider the interaction between elements will cause the alloy properties to vary widely, making it impossible to obtain alloys with excellent performance. Even if the composition standards widely accepted in the industry are followed, the alloy properties will vary greatly and cannot be obtained. Accurately guarantee comprehensive performance. Moreover, in actual industrial production, technicians usually manufacture alloys based on empirical ingredients. Coupled with the complexity of the preparation process, rational alloy composition design and preparation cannot be carried out. In fact, this is also a common problem faced by all industrial alloys, that is, their element types and composition ranges come from engineering practice, and their theoretical basis is missing. Mechanistically, the above engineering problems originate from people's understanding of the structure of solid solutions. As we all know, industrial alloys are all based on solid solutions, and solid solutions are structurally characterized by chemical near-programs, which have both order and disorder. The alloy components must be implicit in this near-program structure, but the academic community is missing the focus on solid solution chemical near-programs. structural model.

In view of this, in order to provide the ideal composition formula of C70350 copper alloy and clarify the composition range of Ni, Co, and Si elements in C70350 copper alloy, it is urgent to propose a new composition of C70350 copper alloy based on the cluster method to establish the synergistic change relationship of compositions. standards, and implement alloy composition design and corresponding preparation processes in accordance with the new standards to ensure performance improvement.

Contents of the invention

The purpose of the present invention is to provide a C70350 alloy that establishes a synergistic change relationship between components based on the cluster method. According to the cluster plus connected atomic model, the component carrier of any alloy is a local structural unit, covering the first neighbor cluster plus several The second nearest neighbor connects the atoms, which is expressed as the cluster formula: [cluster center - cluster first nearest neighbor shell] (the second nearest neighbor connects the atoms). Therefore, the elements in the alloy are only divided into three parts: center, shell and connection. Classes, coupled with interstitial and trace elements that do not enter clusters, therefore only four element classifications are needed, which can simplify the complex alloying of high-temperature alloys. Based on this, this application concludes that the various elements in the C70350 copper alloy and the relationships between the elements The relationship between the composition range and proportion changes is proposed, and a new alloy design method is proposed, which can solve the problem of difficult control of existing C70350 copper alloy elements and reduce the difficulty of alloy design for those skilled in the field. And through the corresponding preparation process in this patent, samples in different states can be obtained, with high preparation efficiency, energy saving and excellent performance, which can meet different processing needs.

In order to achieve the above object, the present invention provides the following technical solution: a C70350 alloy that establishes a synergistic change relationship of components based on the cluster method, and divides the C70350 alloying elements into matrix Cu elements and Ni-like elements that enter the cluster formula: Contains Ni, Co; Si elements; and trace elements that do not enter the cluster formula: Contains Pb, Fe, Zn, Mn, Mg;

The cooperative change relationship of each element in the cluster formula converted into atomic percentage is: 1.05≤Ni/Co≤1.51, 1.66≤(Ni+Co)/Si≤2.89,

Based on the synergistic change relationship of each element, the number of atoms occupied by Ni, Co, and Si elements in the cluster formula ranges from 8 ≤ Ni + Co + Si ≤ 16.

Further, based on the synergistic change relationship of each element, the general formula of the composition of the C70350 alloy is Cu _x (Ni,Co) _y Si _z , where x is the atomic percentage of the Cu element, and z is the atoms of the Si element. Percentage, y is the total atomic percentage of Ni and Co elements, x+y+z≈100.

Furthermore, based on the synergistic change relationship of each element, the mass percentage of each element in the cluster formula is: 94.14≤Cu≤95.70, 1.56≤Ni≤2.34, 1.17≤Co≤1.95, Si≈1.56.

Furthermore, based on the synergistic change relationship of each element, the mass percentage of each element in the cluster formula is: 95.70≤Cu≤96.88, 1.17≤Ni≤1.56, 0.78≤Co≤1.56, Si≈1.17.

Further, the atomic clusters in the C70350 alloy are Si, Ni, Co, and Cu elements jointly forming [Cu ₁ to ₈ (Ni,Co) ₅ to ₁₁ Si ₃ to ₄ ][Cu ₁₆ ] ₁₅ face-centered cubic clusters .

A method for preparing a C70350 alloy based on a cluster method to establish a synergistic change relationship between components, including the following steps: converting elements from atomic percentages to mass percentages for proportioning, and using a vacuum medium-frequency magnetic levitation melting furnace under the protection of an argon atmosphere. The prepared alloy raw materials are melted multiple times to achieve uniform composition, and finally an alloy ingot is obtained. After the ingot is obtained, the actual composition is measured and compared with the nominal composition to ensure that the experimental error is within the design range.

To sum up, the present invention has the following beneficial effects:

First, the composition of the C70350 alloy under traditional industrial standards has been refined, taking into account the proportional changes between various elements, so that the alloy composition and performance can be well matched.

Second, the two-level specification is designed strictly according to the cluster method, that is, when 1.05≤Ni/Co≤1.51(at.), 1.66≤(Ni+Co)/Si≤2.89(at.), 8≤Ni +Co+Si≤16(256), 94.14≤Cu≤95.70, 1.56≤Ni≤2.34, 1.17≤Co≤1.95, Si≈1.56 or 95.70≤Cu≤96.88, 1.17≤Ni≤1.56, 0.78≤Co ≤1.56, Si≈1.17.

Third, the method of this application uses a vacuum medium frequency suspension furnace to prepare samples, which can control the order and time of feeding, reduce losses during the smelting process, and make the actual composition closer to the nominal composition. The equipment has a magnetic stirring function, and repeated smelting can ensure Sample homogeneity.

This application designs alloy components through a cluster plus connected atom model. According to this model, the component carrier of any alloy is a local structural unit, covering the first neighbor cluster plus several sub-neighbor connected atoms, expressed as a cluster formula: [Cluster center-cluster first neighbor shell] (second nearest neighbor connecting atoms), therefore, the elements in the alloy are only divided into three categories: center, shell, and connection, plus those that do not enter the cluster Interstitial and trace elements, so only four element classifications are needed, which can simplify the complex alloying of high-temperature alloys. Based on this, this application derives the composition range and proportional change relationship of each element in the C70350 copper alloy and between the elements, which can solve the current problem. There is a problem that C70350 copper alloy elements are difficult to control.

This application is based on the "cluster plus connected atom model" of chemical near-program structure, which strictly stipulates the collaborative change relationship of alloy components and the composition interval of individual alloy elements, fundamentally overcoming the traditional problems of different composition intervals and composition uncertainty. shortcomings, and the existing preparation process has been improved. Through the corresponding preparation process in this application, samples in different states can be obtained, with high preparation efficiency, energy saving and excellent performance, which can meet different processing needs.

This application analyzes the composition of C70350 copper alloy by introducing a cluster composition design method that describes the chemical near-program structure (the full text is referred to as the cluster method), and gives the ideal composition formula of the alloy, especially considering the synergy of elements in the alloy. Function, a new standard for the composition of C70350 copper alloy is provided based on the cluster method to establish the synergistic change relationship of the components. In strict accordance with the new standard, the composition range of Ni, Co, and Si elements in the C70350 copper alloy is clarified, and the optimization is given The specific ingredient points after. Implementing alloy composition design and corresponding preparation processes in accordance with new standards can ensure improved performance. The new composition standards are simple and effective and will revolutionize the way alloys are standardized for composition. This standard also serves as a demonstration and its significance covers any industrial alloy system.

Description of the drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting any creative effort.

Figure 1 is a Cu-(Ni,Co)-Si pseudo-ternary composition diagram of the C70350 copper alloy composition disclosed in the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to Figure 1 in the embodiments of the present invention. Obviously, the described implementation Examples are part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

In order to realize the C70350 alloy that establishes the synergistic change relationship of components based on the cluster method in this application, the idea is to use the cluster method to analyze the composition of the C70350 copper alloy. This model believes that elements form cluster-type structural units according to interaction patterns, which can be expressed as a simple cluster composition formula [cluster] (connected atoms) _x , that is, a cluster matches x connected atoms. For face-centered cubic alloys, the number of connected atoms x = 1 to 5 can be calculated through the cluster model. In the case of close to equal diameters, the number of connected atoms x = 3. In the presence of large atoms such as Nb and Ti, the number of connected atoms The number of atoms x=5. This cluster composition design method has been successfully applied to the design of a variety of engineering alloys such as high-temperature austenitic stainless steel, low-elastic Ti alloys, cobalt-based high-temperature alloys, etc., providing a new approach to the composition design of high-performance engineering alloys. ideas and methods.

In the C70350 alloy, the elements can be divided into matrix Cu, precipitation strengthening elements Ni, Co, Si, and trace elements (Pb, Fe, Zn, Mn, Mg) that do not enter the cluster formula. According to the applicant's previous work, in the cluster formula, combined with the element interaction model, it can be calculated that the cluster formula contains 16 atoms, with Si as the center, and Ni, Co, and Cu elements together form the first nearest neighbor [Si -(Ni,Co,Cu) ₁₂ ] cuboctahedral cluster. Convert the elemental components entering the cluster formula into the number of 16 atoms, and the general formula of the alloy composition is obtained:

or/>

From this, we can get the mass percentage of C70350 copper alloy under the limited conditions of component ratio: 1.05≤Ni/Co≤1.51(at.), 1.66≤(Ni+Co)/Si≤2.89(at.), 8≤ Under the limited element ratio of Ni+Co+Si≤16(256),

When the alloy component ratio satisfies the general formula {A}, each element satisfies 94.14≤Cu≤95.70(at.%), 1.56≤Ni≤2.34(at.%), 1.17≤Co≤1.95(at.%) ), Si≈1.56(at.%);

When the alloy component ratio satisfies the general formula {B}, each element satisfies 95.70≤Cu≤96.88(at.%), 1.17≤Ni≤1.56(at.%), 0.78≤Co≤1.56(at.%) ), Si≈1.17 (at.%).

Examples and performance measurements

The preparation method of the C70350 copper alloy involved in this application is:

S1: Use high-purity metal materials and batch them according to mass percentage. Use a vacuum medium frequency melting furnace to smelt the batches at least twice under the protection of argon atmosphere to obtain an alloy ingot with a uniform composition and a mass of about 2kg. After smelting Quality loss during the process does not exceed 0.1%.

S2: Use a muffle furnace to homogenize the alloy ingot. The homogenization temperature is 930°C and the processing time is 4 hours. Then, 5 passes of hot rolling were performed to obtain a 16mm plate sample. Afterwards, the solid solution alloy material designed in the present invention can be obtained by solid solution treatment at 975°C for 2 hours, and water cooling to room temperature;

S3: The alloy after solid solution is cold rolled, divided into 29 passes, to obtain a 2mm plate sample, and then aged at 450°C for 2 hours to obtain the aged alloy material designed in the present invention.

The microstructure and performance analysis methods of the C70350 copper alloy involved in this application are:

Conduct metallographic preparation of the as-cast structure, and use a light microscope to initially observe the microscopic morphology of the sample;

Use a scanning electron microscope to observe the structural pattern of the sample in detail, and granular precipitates can be observed in the grains and at the grain boundaries;

The phase composition of the alloy was analyzed using an X-ray diffractometer, and combined with EDS analysis, it was found that the second phase in the alloy was mainly (Ni,Co) ₂ Si phase;

Use a vacuum Vickers hardness tester to measure the hardness of the sample at room temperature;

Use SMP350 conductivity tester to test the conductivity of the sample.

When the alloy component ratio satisfies the general formula {A}, in the C70350 alloy, the atomic percentage content of the matrix Cu element is 94.92±0.78at.%, and the atomic percentage content of the second phase strengthening element Ni is 1.95±0.39at. %, the atomic percentage content of Co is 1.56±0.39 at.%, and the atomic percentage content of Si is 1.56 at.%, the composition points of the C70350 copper alloy are shown in Table 1.

Table 1 Composition analysis table of C70350 copper alloy of Examples 1-6

Table 2 Hardness of C70350 copper alloy in Examples 1-6

Table 3 Electrical conductivity of C70350 copper alloy in Examples 1-6

It can be seen from Table 1-3 that taking Example 2 and Example 3 as examples, when the Ni content increases from 1.56at.% to 1.95at.%, the hardness of the alloy in the solid solution state is 184kgf·mm ^-2 and 171kgf·mm ^-2 . Similarly, the hardnesses in the aged state are 220kgf·mm ^-2 and 235kgf·mm ^-2 respectively. From the perspective of composition formula, Example 3 only has one more Ni atom than Example 2. This shows that C70350 alloy is a composition-sensitive alloy, and small changes in composition will lead to large changes in performance. Conventional trial and error methods, Hume-Rothery rules, etc. cannot meet the needs of ingredient design. Only by using the "cluster plus connected atomic model" can we connect the composition and performance of the alloy from an atomic perspective.

Combining Table 1 and Figure 1, it can be seen that triangles and hexagons are the component points that meet the limiting conditions of the 16-atom cluster formula [Cu ₁ ~ ₅ (Ni,Co) ₇ ~ ₁₁ Si ₄ ][Cu ₁₆ ] ₁₅ and [Cu ₅ respectively ~ ₈ (Ni,Co) ₅ ~ ₈ Si ₃ ][Cu ₁₆ ] ₁₅ .

When the alloy component ratio satisfies the general formula {B}, in the C70350 alloy, when the atomic percentage content of the matrix Cu element is 96.29±0.59at.%, the atomic percentage content of the second phase strengthening element Ni is 1.37±0.20at. .%, the atomic percentage content of Co is 1.17±0.39at.%, the atomic percentage content of Si is 1.17at.%, the composition points of C70350 copper alloy are shown in Table 4.

Table 4 Composition analysis table of C70350 copper alloy of Examples 7-10

Table 5 Hardness of C70350 copper alloy in Examples 7-10

Table 6 Electrical conductivity of C70350 copper alloy in Examples 7-10

Table 4-6 Compared with Table 1-3, [Cu ₅ ~ ₈ (Ni,Co) ₅ ~ ₈ Si ₃ ][Cu ₁₆ ] ₁₅ alloy has a hardness increased to Around 250HV. The component points of Examples 7-10 are the hexagons in Figure 1. We can see that these component points are all within the industrial standard range. We call this group the experimental group. The component points of Examples 1-6 are triangles in Figure 1. We can see that most of these component points are outside the industrial standard range. We call this group the control group. Comparing the two groups, it can be found that the overall alloy performance of the experimental group is better than that of the control group, which also verifies the rationality of the industrial standard range.

In summary, compared with the existing technology, the C70350 copper alloy under the new standard provided by the present invention has creativity in the following aspects: aiming to obtain a high-performance Cu-Ni-Co-Si alloy for lead frames, using "clusters" "Add connected atomic model" to analyze and optimize the composition of C70350 alloy. The target material is obtained through casting preparation and subsequent heat treatment process. The composition model-microstructure-electrical (mechanical) properties are closely combined to obtain an analytical model for high-performance copper alloy composition design, and apply it to related alloys.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, but not to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features can be equivalently replaced; and these modifications or substitutions do not deviate from the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention. scope.

Claims (5)

1. C70350 alloy with a composition cooperative change relation established based on a cluster method is characterized in that C70350 alloying elements are divided into matrix Cu elements entering the cluster; ni-like element: contains Ni and Co; si element; and trace elements that do not enter into clusters: pb, fe, zn, mn, mg; converting the element components entering into clusters into 16 atoms to obtain the alloy with the general formula of the components

Or->

The cooperative change relation of each element in the cluster is converted into atomic percent: ni/Co is more than or equal to 1.05 and less than or equal to 1.51,1.66, (Ni+Co)/Si is more than or equal to 2.89,

based on the synergistic change relation of each element, the atomic number range of Ni, co and Si elements in the cluster formula is as follows: ni+Co+Si is more than or equal to 8 and less than or equal to 16;

a preparation method of C70350 alloy for establishing a composition cooperative change relation based on a cluster method comprises the following steps:

solid solution state: carrying out solution treatment for 2 hours at 975+/-10 ℃, and carrying out water cooling or oil cooling to room temperature;

aging state: preserving heat for 2h at 450+/-10 ℃, and cooling to room temperature in a furnace or water cooling.

2. The C70350 alloy according to claim 1, wherein the C70350 alloy has a composition formula of Cu based on the synergistic effect of the respective elements _x (Ni,Co) _y Si _z Wherein x is the atomic percent of Cu element, z is the atomic percent of Si element,y is the total atomic percent of Ni and Co elements, x+y+z=100.

3. The C70350 alloy for establishing a composition cooperative variation relationship based on a cluster method according to claim 1 or 2, wherein on the basis of the cooperative variation relationship of the respective elements, the mass percentage of each element in the cluster is: cu is more than or equal to 94.14 and less than or equal to 95.70,1.56, ni is more than or equal to 2.34,1.17 and Co is more than or equal to 1.95, and Si is more than or equal to 1.56.

4. The C70350 alloy for establishing a composition cooperative variation relationship based on a cluster method according to claim 1 or 2, wherein on the basis of the cooperative variation relationship of the respective elements, the mass percentage of each element in the cluster is: 95.70 Cu is less than or equal to 96.88,1.17 Ni is less than or equal to 1.56,0.78 Co is less than or equal to 1.56, and Si=1.17.

5. A method for producing the C70350 alloy as claimed in any one of claims 1 to 4, comprising the steps of:

solid solution state: carrying out solution treatment for 2 hours at 975+/-10 ℃, and carrying out water cooling or oil cooling to room temperature; aging state: preserving heat for 2h at 450+/-10 ℃, and cooling to room temperature in a furnace or water cooling.