CN114672711A

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Publication number: CN114672711A
Application number: CN202210399227.2A
Authority: CN
Inventors: 蒋斌; 王翠红; 宋江凤; 董志华; 吴素娟; 钱晓英; 郑志莹; 李旭; 潘复生
Original assignee: Chongqing University
Current assignee: Henan Magnesium Industry Co ltd
Priority date: 2022-04-15
Filing date: 2022-04-15
Publication date: 2022-06-28
Anticipated expiration: 2042-04-15
Also published as: CN114672711B

Abstract

The invention discloses a novel low-expansion binary magnesium alloy and a preparation method thereof, wherein the magnesium alloy comprises the following components in percentage by mass: 1.6-15.5% of Gd, and the balance of magnesium and inevitable impurity elements, wherein the thermal expansion coefficient of the magnesium alloy at room temperature is 15.7 multiplied by 10^‑6K^‑1～16.4×10^‑6K^‑1. According to the invention, by adopting a mode of combining the precise control of the content of Gd element and the solution treatment process, the content of the second phase in the alloy is greatly reduced, a large amount of phase interfaces with a magnesium substrate are avoided, and the thermal expansion coefficient of the magnesium alloy is effectively reduced. The Mg-Gd alloy disclosed by the invention not only has low thermal expansion coefficient, but also has good plastic processing performance, greatly improves the potential of the Mg-Gd alloy as a repair welding material or an electronic element material, and expands the possible application of the magnesium alloyIn the field of engineering, a new research direction is provided for the research of preparing the low-expansion magnesium alloy, and the method has great significance.

Description

Translated fromChinese

一种新型低膨胀二元镁合金及其制备方法A novel low-expansion binary magnesium alloy and preparation method thereof

技术领域technical field

本发明涉及镁合金铸造制备技术领域，特别的涉及一种新型低膨胀二元镁合金及其制备方法。The invention relates to the technical field of magnesium alloy casting preparation, in particular to a novel low-expansion binary magnesium alloy and a preparation method thereof.

背景技术Background technique

由于镁合金具有高比强度、低密度、良好的铸造加工性和良好的可回收性，被认为是一种很有前途的结构应用。镁合金资源丰富，并且轻量化效果显著，其大规模应用对于节能减排和缓解我国资源紧张有很重要的作用，因此大规模应用于地面运输、航空航天及3c电子等领域。Magnesium alloys are considered to be a promising structural application due to their high specific strength, low density, good castability, and good recyclability. Magnesium alloys are rich in resources and have significant lightweight effects. Their large-scale application plays an important role in energy conservation and emission reduction and alleviating resource shortages in my country. Therefore, they are widely used in ground transportation, aerospace, and 3c electronics.

然而，室温时纯镁的热膨胀系数(CTE)较高，约为26×10^-6K^-1，致使铸造热应力大，从而产生大量的缩松、缩孔和裂纹等铸造缺陷，大幅降低构件的成品率(部分构件一次成品率低于5％)，并且对铸造缺陷进行补焊修复过程中产生的热应力大使补焊区域极易开裂，甚至引起非补焊区域开裂，二次成品率仍然不高(低于20％)。另外，在高温环境下服役时，由于镁基体CTE更高，温度变化产生的热应力会使合金屈服，甚至失效，因此，现有的镁合金材料在许多涉及热影响的电子元器件领域的应用受到很大的限制，用作电子封装基板的金属构件的热膨胀系数应小于常用金属构件的热膨胀系数，如<19.0×10^-6K^-1，这大大限制了镁合金的推广应用。因此亟需生产出低膨胀、热稳定高的新型镁合金。However, the coefficient of thermal expansion (CTE) of pure magnesium at room temperature is relatively high, about 26×10^-6 K^-1 , resulting in large thermal stress in casting, resulting in a large number of casting defects such as shrinkage porosity, shrinkage cavities and cracks, which greatly reduces the component (the primary yield of some components is lower than 5%), and the thermal stress generated during the repair welding and repair of casting defects makes the repair welding area easy to crack, and even causes cracking in the non-repair welding area, and the secondary yield is still Not high (below 20%). In addition, when serving in a high temperature environment, due to the higher CTE of the magnesium matrix, the thermal stress generated by the temperature change will cause the alloy to yield or even fail. Therefore, the existing magnesium alloy materials are used in many fields of electronic components that involve thermal effects. Due to great restrictions, the thermal expansion coefficient of metal components used as electronic packaging substrates should be smaller than that of commonly used metal components, such as <19.0×10^-6 K^-1 , which greatly limits the popularization and application of magnesium alloys. Therefore, it is urgent to produce new magnesium alloys with low expansion and high thermal stability.

合金化添加元素到镁基体中能够有效影响镁合金的CTE。目前，现有研究通常是引入高熔点、低膨胀系数第二相使镁合金的CTE大大降低。例如发明专利CN108486446B公开了一种低膨胀镁合金及其制备方法，该镁合金包括以下组分：Si：3.2％～8.0％，Ce：0.32％～1.2％，Ca：0.3％～0.8％，其余为Mg和不可避免的杂质元素，对原料进行预热、熔炼、变质处理及除气精炼，以此获得合金液，将合金液浇入金属模具内，冷却、凝固后得到镁合金产品。其中低膨胀Mg-Si合金，虽然Mg₂Si熔点高，热膨胀系数低，但是Si在镁基体中固溶度低，会生成大量的Mg₂Si脆性相，使镁合金的塑性极低。也有研究通过外加低/负热膨胀系数粒子(SiC、AlN、Al₂O₃和Zr₂(WO₄)(PO₄)₂等)获得低热膨胀系数镁合金，添加量比较高，在20％～50％，并且这些粒子大多为刚性相，与Mg基体形成许多相界面，服役过程中会在这些相界面处产生急剧的应力集中。又如发明专利CN109182855B公开了一种可变形低膨胀Mg-Zr合金，通过粉末冶金途径并结合高温退火工艺来合成含锆35～45wt.％的Mg-Zr合金，该合金不仅具有低的线膨胀系数，同时具有良好的塑性加工性能。但稀有金属锆的含量高，大大增加了生产成本。The addition of alloying elements to the magnesium matrix can effectively affect the CTE of magnesium alloys. At present, the existing research usually introduces the second phase with high melting point and low expansion coefficient to greatly reduce the CTE of magnesium alloys. For example, invention patent CN108486446B discloses a low-expansion magnesium alloy and its preparation method. The magnesium alloy includes the following components: Si: 3.2%-8.0%, Ce: 0.32%-1.2%, Ca: 0.3%-0.8%, and the rest For Mg and unavoidable impurity elements, the raw materials are preheated, smelted, metamorphic, and degassed to obtain an alloy liquid. The alloy liquid is poured into a metal mold, cooled and solidified to obtain a magnesium alloy product. Among them, low-expansion Mg-Si alloy, although Mg₂ Si has a high melting point and a low thermal expansion coefficient, the solid solubility of Si in the magnesium matrix is low, and a large amount of Mg₂ Si brittle phase will be formed, making the ductility of the magnesium alloy extremely low. There are also studies to obtain low thermal expansion coefficient magnesium alloys by adding low/negative thermal expansion coefficient particles (SiC, AlN, Al₂ O₃ and Zr₂ (WO₄ ) (PO₄ )₂ , etc.), and the addition amount is relatively high. %, and most of these particles are rigid phases, forming many phase interfaces with the Mg matrix, and sharp stress concentration will be generated at these phase interfaces during service. Another example is the invention patent CN109182855B, which discloses a deformable low-expansion Mg-Zr alloy. The Mg-Zr alloy containing 35-45wt.% zirconium is synthesized by powder metallurgy and high-temperature annealing process. The alloy not only has low linear expansion coefficient, and at the same time has good plastic workability. However, the high content of rare metal zirconium greatly increases the production cost.

之前的研究发现：在镁中加入合金元素形成镁合金时，许多常用合金元素反而使镁的热膨胀系数进一步增大，如Gd、La、Al、Zn等元素，有的添加后镁合金甚至超过30×10^-⁶K^-1(参见发明专利CN 108486446 A)，因此目前还未有通过添加Gd元素来降低镁合金的膨胀系数的相关报道。Previous studies have found that when adding alloying elements to magnesium to form magnesium alloys, many commonly used alloying elements further increase the thermal expansion coefficient of magnesium, such as Gd, La, Al, Zn and other elements, and some magnesium alloys even exceed 30 after adding them. ×10^-⁶ K^-1 (see invention patent CN 108486446 A), so there is no relevant report on reducing the expansion coefficient of magnesium alloys by adding Gd element.

发明内容SUMMARY OF THE INVENTION

针对上述现有技术的不足，本发明所要解决的技术问题是：如何提供一种新型低膨胀二元镁合金及其制备方法，解决现有镁合金在降低膨胀系数的同时仍存在脆性第二相、与基体存在许多相界面和成本高等问题。Aiming at the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is: how to provide a novel low-expansion binary magnesium alloy and a preparation method thereof, so as to solve the problem that the existing magnesium alloy still has a brittle second phase while reducing the expansion coefficient , There are many interface and high cost problems with the matrix.

为了解决上述技术问题，本发明采用了如下的技术方案：一种新型低膨胀二元镁合金，所述镁合金包括以下质量分数的组分：Gd 1.6～15.5％，其余为镁和不可避免的杂质元素；所述镁合金在室温下的热膨胀系数为15.7×10^-6K^-1～16.4×10^-6K^-1。In order to solve the above technical problems, the present invention adopts the following technical scheme: a novel low-expansion binary magnesium alloy, the magnesium alloy includes the following components in mass fraction: Gd 1.6-15.5%, and the rest is magnesium and unavoidable impurity element; the thermal expansion coefficient of the magnesium alloy at room temperature is 15.7×10^-6 K^-1 to 16.4×10^-6 K^-1 .

通过Thermal-Calc计算软件算出Gd元素在553℃时固溶度最大，为20.2％，但固溶处理温度选择不宜过高，避免过烧现象的发生；而通常选择固溶处理的温度范围为500～520℃，经多次试验发现，此条件下镁合金中Gd的固溶量最大为15.5％。因此，若Gd成分过高，固溶处理不能使Gd元素完全固溶到镁基体中，仍有大量Mg₅Gd相的析出，出现明显界面；若Gd成分过低，达不到降低热膨胀的效果。Through Thermal-Calc calculation software, it is calculated that the solid solubility of Gd element is the largest at 553 ℃, which is 20.2%, but the temperature of solution treatment should not be too high to avoid the occurrence of over-burning; and usually the temperature range of solution treatment is 500 ～520℃, after many tests, it is found that the maximum solid solution amount of Gd in the magnesium alloy is 15.5% under this condition. Therefore, if the Gd composition is too high, the solution treatment cannot completely dissolve the Gd element into the magnesium matrix, and a large amount of Mg₅ Gd phase is still precipitated, resulting in an obvious interface; if the Gd composition is too low, the effect of reducing thermal expansion cannot be achieved. .

本发明的另一目的，还在于提供了一种新型低膨胀二元镁合金的制备方法，包括以下步骤：Another object of the present invention also provides a method for preparing a novel low-expansion binary magnesium alloy, comprising the following steps:

1)以纯镁锭、镁钆中间合金为原料，按组分的质量百分比计算配料；1) Use pure magnesium ingot and magnesium-gadolinium master alloy as raw materials, and calculate the batching according to the mass percentage of the components;

2)先将称量好的原材料进行预热，然后将预热好的纯镁锭在动态保护气氛下加热至720～750℃，熔化得到镁熔体，再加入预热好的镁钆中间合金，保温15～20min，得到镁合金熔体；2) First preheat the weighed raw materials, then heat the preheated pure magnesium ingot to 720-750℃ in a dynamic protective atmosphere, melt to obtain a magnesium melt, and then add the preheated magnesium-gadolinium master alloy , keep the temperature for 15-20min to obtain a magnesium alloy melt;

3)将步骤2)得到的镁合金熔体充分搅拌，于720～750℃保温静置10～15min后，然后将其注入预热的金属模具中，冷却至室温，脱模后得到镁合金铸锭；3) Fully stirring the magnesium alloy melt obtained in step 2), keeping it at 720-750° C. for 10-15 minutes, then injecting it into a preheated metal mold, cooling it to room temperature, and demoulding to obtain a magnesium alloy cast. ingot;

4)将步骤3)得到的铸锭放入热处理炉中进行固溶处理，得到Gd元素分布均匀的镁合金，即所述低膨胀二元镁合金。4) Put the ingot obtained in step 3) into a heat treatment furnace for solution treatment to obtain a magnesium alloy with a uniform distribution of Gd elements, that is, the low-expansion binary magnesium alloy.

由于金属钆与镁同为密排六方晶体结构，两者具有良好的热力学相容性，金属Gd熔点高，为1587K，原子间结合力大，且Gd元素固溶度大，将Mg-Gd铸锭在合适温度下进行固溶处理后，使Gd元素固溶并均匀分布在镁基体中，合金中生成的第二相数量大大减少，进而避免与镁基体产生大量的相界面，从而解决了直接加入Gd会提高镁合金的热膨胀系数，且Gd的添加可以显著细化晶粒，进一步提高了合金的塑性加工性能。Since both gadolinium and magnesium are close-packed hexagonal crystal structures, the two have good thermodynamic compatibility. The melting point of metal Gd is 1587K, the interatomic bonding force is large, and the solid solubility of Gd element is large. Mg-Gd cast After the ingot is solution-treated at a suitable temperature, the Gd element is dissolved and uniformly distributed in the magnesium matrix, and the number of second phases generated in the alloy is greatly reduced, thereby avoiding a large number of phase interfaces with the magnesium matrix, thus solving the direct problem. The addition of Gd can increase the thermal expansion coefficient of magnesium alloys, and the addition of Gd can significantly refine the grains and further improve the plastic workability of the alloys.

进一步，所述保护气氛为CO₂与SF₆混合气体，其配比为99：1。Further, the protective atmosphere is a mixed gas of CO₂ and SF₆ with a ratio of 99:1.

进一步，所述镁钆中间合金为Mg-30wt.％Gd。Further, the magnesium-gadolinium master alloy is Mg-30wt.%Gd.

进一步，所述预热的温度为200～250℃。Further, the temperature of the preheating is 200-250°C.

进一步，所述固溶处理的温度为500～520℃，时间为12～18h。这样，使第二相数量减少以达到减少相界面的目的。Further, the temperature of the solution treatment is 500-520° C., and the time is 12-18 h. In this way, the number of the second phase is reduced to achieve the purpose of reducing the phase interface.

本发明的另一个目的，还在于提供了上述新型低膨胀二元镁合金在制备补焊材料或电子元件材料方面的应用。Another object of the present invention is to provide the application of the above-mentioned novel low-expansion binary magnesium alloy in the preparation of repair welding materials or electronic component materials.

相比现有技术，本发明具有如下有益效果：Compared with the prior art, the present invention has the following beneficial effects:

1、本发明通过采用精准控制Gd元素含量和固溶处理工艺相结合的方式，大大降低合金中第二相含量，同时避免与镁基体产生大量的相界面，这对于减少合金在服役过程中相界面处产生急剧的应力集中有很积极的作用，从而避免了直接加入Gd会提高镁合金的热膨胀系数的技术难题。1. The present invention greatly reduces the content of the second phase in the alloy by combining the precise control of the Gd element content with the solution treatment process, and at the same time avoids the generation of a large number of phase interfaces with the magnesium matrix, which is important for reducing the phase of the alloy during service. The sharp stress concentration at the interface has a very positive effect, thus avoiding the technical problem that the direct addition of Gd will increase the thermal expansion coefficient of the magnesium alloy.

2、本发明所制备的Mg-Gd合金不仅具有低的热膨胀系数，同时具有良好的塑性加工性能。该Mg-Gd合金在室温下的热膨胀系数范围为15.7×10^-6K^-1～16.4×10^-6K^-1，在298～373K温度范围内的平均热膨胀系数范围为18.9×10^-6K^-1～20.6×10^-6K^-1。另外，良好的塑性有利于后续变形和冷加工，极大地提升了其作为补焊材料或电子元件材料的潜力，拓展了镁合金可能应用的工程领域，同时也为制备低膨胀镁合金的研究提供了新的研究方向，具有重大意义。2. The Mg-Gd alloy prepared by the present invention not only has low thermal expansion coefficient, but also has good plastic workability. The thermal expansion coefficient of the Mg-Gd alloy at room temperature is in the range of 15.7×10^-6 K^-1 to 16.4×10^-6 K^-1 , and the average thermal expansion coefficient in the temperature range of 298 to 373K is in the range of 18.9×10^-6 K^-1 to 20.6×10^-6 K^-1 . In addition, good plasticity is conducive to subsequent deformation and cold working, which greatly enhances its potential as a repair welding material or electronic component material, expands the engineering field of possible applications of magnesium alloys, and also provides research on the preparation of low-expansion magnesium alloys. New research directions are of great significance.

3、本发明所用的设备简单，合金元素含量低，成本较低，加工工艺操作简单、方便，易于工业化大规模生产。3. The equipment used in the present invention is simple, the content of alloy elements is low, the cost is low, the processing technology is simple and convenient to operate, and it is easy to industrialize large-scale production.

附图说明Description of drawings

图1为本发明实施例1制备Mg-Gd合金的SEM图。FIG. 1 is a SEM image of the Mg-Gd alloy prepared in Example 1 of the present invention.

图2为本发明实施例1制备Mg-Gd合金的热膨胀曲线图。FIG. 2 is a thermal expansion curve diagram of the Mg-Gd alloy prepared in Example 1 of the present invention.

图3为本发明实施例2制备Mg-Gd合金的SEM图。3 is a SEM image of the Mg-Gd alloy prepared in Example 2 of the present invention.

图4为本发明实施例2制备Mg-Gd合金的热膨胀曲线图。4 is a thermal expansion curve diagram of the Mg-Gd alloy prepared in Example 2 of the present invention.

图5为本发明实施例3制备Mg-Gd合金的SEM图。5 is a SEM image of the Mg-Gd alloy prepared in Example 3 of the present invention.

图6为本发明实施例3制备Mg-Gd合金的热膨胀曲线图。6 is a thermal expansion curve diagram of the Mg-Gd alloy prepared in Example 3 of the present invention.

图7为本发明实施例4制备Mg-Gd合金的SEM图。7 is a SEM image of the Mg-Gd alloy prepared in Example 4 of the present invention.

图8为本发明实施例4制备Mg-Gd合金的热膨胀曲线图。FIG. 8 is a thermal expansion curve diagram of the Mg-Gd alloy prepared in Example 4 of the present invention.

具体实施方式Detailed ways

下面结合实施例对本发明作进一步的详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。The present invention will be further described in detail below in conjunction with the examples. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

实施例1Example 1

1)一种二元Mg-Gd低膨胀镁合金材料，其中Gd元素含量为1.6wt.％左右，其余为Mg及不可避免的杂质元素，按照上述成分进行备料并将原材料打磨出金属光泽后称量待用，所用原料为高纯Mg(99.99wt.％)和Mg-30wt.％Gd中间合金。1) A binary Mg-Gd low-expansion magnesium alloy material, wherein the content of Gd element is about 1.6wt.%, and the rest are Mg and inevitable impurity elements. Prepare materials according to the above-mentioned components and polish the raw materials to give a metallic luster. The amount is ready for use, and the raw materials used are high-purity Mg (99.99wt.%) and Mg-30wt.%Gd master alloy.

2)将称量好的原材料分别放进热处理炉中预热，预热温度为250℃，然后将预热好的纯镁放入电阻炉中，熔炼温度设定为730℃，在动态保护气氛CO₂与SF₆混合气体(配比为99:1)下加热，待熔化后再放入预热好的Mg-30wt.％Gd中间合金，保温15～20min，形成合金熔体。2) Put the weighed raw materials into the heat treatment furnace for preheating, the preheating temperature is 250 ℃, then put the preheated pure magnesium into the resistance furnace, the melting temperature is set to 730 ℃, in a dynamic protective atmosphere Heating under the mixed gas of CO₂ and SF₆ (the ratio is 99:1), after melting, put the preheated Mg-30wt.

3)对步骤2)得到的镁合金熔体搅拌2min，730℃保温静置10min，清除熔体表面的熔渣后，将合金熔体浇入事先250℃预热的低碳钢模具中，冷却至室温，脱模后得到镁合金铸锭，再将铸锭放入热处理炉中于520℃固溶处理12h，即得到所述低膨胀二元镁合金。3) The magnesium alloy melt obtained in step 2) was stirred for 2 minutes, kept at 730° C. for 10 minutes, and after removing the slag on the surface of the melt, the alloy melt was poured into a low-carbon steel mold preheated at 250° C. and cooled. After reaching room temperature, the magnesium alloy ingot is obtained after demoulding, and then the ingot is put into a heat treatment furnace for solution treatment at 520° C. for 12 hours to obtain the low-expansion binary magnesium alloy.

将本实施例制备的Mg-1.6Gd合金在电子显微镜下观察，结果如图1所示。从图中可以看出，Gd元素固溶并均匀分布在镁基体中，合金中生成的第二相数量少，并且弥散分布，没有明显的相界面。The Mg-1.6Gd alloy prepared in this example is observed under an electron microscope, and the result is shown in FIG. 1 . It can be seen from the figure that the Gd element is solid solution and uniformly distributed in the magnesium matrix, and the number of second phases generated in the alloy is small and dispersed, and there is no obvious phase interface.

采用NETZSCH DIL 402C的卧式高温热膨胀仪测试本实施例制备的固溶态Mg-1.6Gd合金的热膨胀系数(CTE)，温度范围为298～673K，升温速率为10K/min，实验过程中采用高纯氩气保护，氩气流速为100ml/min，结果如图2所示。从图中可以看出，在室温时，该合金的CTE为16.4×10^-6K^-1；在673K时，该合金的CTE为29.3×10^-6K^-1；该合金材料在298～373K温度范围内的平均CTE为20.6×10^-6K^-1。The coefficient of thermal expansion (CTE) of the solid solution Mg-1.6Gd alloy prepared in this example was tested by a horizontal high temperature thermal dilatometer of NETZSCH DIL 402C. The temperature range was 298-673K, and the heating rate was 10K/min. Pure argon protection, the argon flow rate is 100ml/min, the results are shown in Figure 2. It can be seen from the figure that at room temperature, the CTE of the alloy is 16.4×10^-6 K^-1 ; at 673K, the CTE of the alloy is 29.3×10^-6 K^-1 ; the alloy material is between 298 and 373K. The average CTE over the temperature range was 20.6×10^-6 K^-1 .

实施例2Example 2

1)一种二元Mg-Gd低膨胀镁合金材料，其中Gd元素含量为4.2wt.％左右，其余为Mg及不可避免的杂质元素，按照上述成分进行备料并将原材料打磨出金属光泽后称量待用，所用原料为高纯Mg(99.99wt.％)和Mg-30wt.％Gd中间合金。1) A binary Mg-Gd low-expansion magnesium alloy material, wherein the content of Gd element is about 4.2wt.%, and the rest are Mg and inevitable impurity elements. Prepare materials according to the above-mentioned components and grind the raw materials to give a metallic luster. The amount is ready for use, and the raw materials used are high-purity Mg (99.99wt.%) and Mg-30wt.%Gd master alloy.

将本实施例制备的Mg-4.2Gd合金在电子显微镜下观察，结果如图3所示。从图中可以看出，Gd元素固溶并均匀分布在镁基体中，合金中生成的第二相数量少，并且弥散分布，没有明显的相界面。The Mg-4.2Gd alloy prepared in this example is observed under an electron microscope, and the result is shown in FIG. 3 . It can be seen from the figure that the Gd element is solid solution and uniformly distributed in the magnesium matrix, and the number of second phases generated in the alloy is small and dispersed, and there is no obvious phase interface.

采用NETZSCH DIL 402C的卧式高温热膨胀仪测试本实施例制备的固溶态Mg-4.2Gd合金的热膨胀系数(CTE)，温度范围为298～673K，升温速率为10K/min，实验过程中采用高纯氩气保护，氩气流速为100ml/min，结果如图4所示。从图中可以看出，在室温时，该合金的CTE为16.3×10^-6K^-1；在673K时，该合金的CTE为29.3×10^-6K^-1；该合金材料在298～373K温度范围内的平均热膨胀系数为19.9×10^-6K^-1。The coefficient of thermal expansion (CTE) of the solid solution Mg-4.2Gd alloy prepared in this example was tested by using a horizontal high temperature thermal dilatometer of NETZSCH DIL 402C. The temperature range was 298-673K, and the heating rate was 10K/min. Pure argon protection, the argon flow rate is 100ml/min, the results are shown in Figure 4. It can be seen from the figure that at room temperature, the CTE of the alloy is 16.3×10^-6 K^-1 ; at 673K, the CTE of the alloy is 29.3×10^-6 K^-1 ; the alloy material is between 298 and 373K. The average thermal expansion coefficient in the temperature range is 19.9×10^-6 K^-1 .

实施例3Example 3

1)一种二元Mg-Gd低膨胀镁合金材料，其中Gd元素含量为10.6wt.％左右，其余为Mg及不可避免的杂质元素，按照上述成分进行备料并将原材料打磨出金属光泽后称量待用，所用原料为高纯Mg(99.99wt.％)和Mg-30wt.％Gd中间合金。1) A binary Mg-Gd low-expansion magnesium alloy material, wherein the content of Gd element is about 10.6wt.%, and the rest are Mg and inevitable impurity elements. Prepare materials according to the above-mentioned components and grind the raw materials into metallic luster. The amount is ready for use, and the raw materials used are high-purity Mg (99.99wt.%) and Mg-30wt.%Gd master alloy.

将本实施例制备的Mg-10.6Gd合金在电子显微镜下观察，结果如图5所示。从图中可以看出，Gd元素固溶并均匀分布在镁基体中，合金中生成的第二相数量少，并且弥散分布，没有明显的相界面。The Mg-10.6Gd alloy prepared in this example is observed under an electron microscope, and the result is shown in FIG. 5 . It can be seen from the figure that the Gd element is solid solution and uniformly distributed in the magnesium matrix, and the number of second phases generated in the alloy is small and dispersed, and there is no obvious phase interface.

采用NETZSCH DIL 402C的卧式高温热膨胀仪测试本实施例制备的固溶态Mg-10.6Gd合金的热膨胀系数(CTE)，温度范围为298～673K，升温速率为10K/min，实验过程中采用高纯氩气保护，氩气流速为100ml/min，结果如图6所示。从图中可以看出，在室温时，该合金的CTE为15.9×10^-6K^-1；在673K时，该合金的CTE为29.1×10^-6K^-1；该合金材料在298～373K温度范围内的平均热膨胀系数为19.7×10^-6K^-1。The coefficient of thermal expansion (CTE) of the solid solution Mg-10.6Gd alloy prepared in this example was tested by a horizontal high temperature thermal dilatometer of NETZSCH DIL 402C. The temperature range was 298-673K, and the heating rate was 10K/min. Pure argon protection, the argon flow rate is 100ml/min, the results are shown in Figure 6. It can be seen from the figure that at room temperature, the CTE of the alloy is 15.9×10^-6 K^-1 ; at 673K, the CTE of the alloy is 29.1×10^-6 K^-1 ; the alloy material is between 298 and 373K. The average thermal expansion coefficient in the temperature range is 19.7×10^-6 K^-1 .

实施例4Example 4

1)一种二元Mg-Gd低膨胀镁合金材料，其中Gd元素含量为15.5wt.％左右，其余为Mg及不可避免的杂质元素，按照上述成分进行备料并将原材料打磨出金属光泽后称量待用，所用原料为高纯Mg(99.99wt.％)和Mg-30wt.％Gd中间合金。1) A binary Mg-Gd low-expansion magnesium alloy material, wherein the content of Gd element is about 15.5wt.%, and the rest are Mg and inevitable impurity elements. Prepare materials according to the above-mentioned components and polish the raw materials to give a metallic luster. The amount is ready for use, and the raw materials used are high-purity Mg (99.99wt.%) and Mg-30wt.%Gd master alloy.

将本实施例制备的Mg-15.5Gd合金在电子显微镜下观察，结果如图7所示。从图中可以看出，Gd元素固溶并均匀分布在镁基体中，合金中生成的第二相数量少，并且弥散分布，没有明显的相界面。The Mg-15.5Gd alloy prepared in this example is observed under an electron microscope, and the result is shown in FIG. 7 . It can be seen from the figure that the Gd element is solid solution and uniformly distributed in the magnesium matrix, and the number of second phases generated in the alloy is small and dispersed, and there is no obvious phase interface.

采用NETZSCH DIL 402C的卧式高温热膨胀仪测试本实施例制备的固溶态Mg-15.5Gd合金的热膨胀系数(CTE)，温度范围为298～673K，升温速率为10K/min，实验过程中采用高纯氩气保护，氩气流速为100ml/min，结果如图8所示。从图中可以看出，在室温时，该合金的CTE为15.7×10^-6K^-1；在673K时，该合金的CTE为28.9×10^-6K^-1；该合金材料在298～373K温度范围内的平均热膨胀系数为18.9×10^-6K^-1。The coefficient of thermal expansion (CTE) of the solid solution Mg-15.5Gd alloy prepared in this example was measured by a horizontal high temperature thermal dilatometer of NETZSCH DIL 402C. The temperature range was 298-673K, and the heating rate was 10K/min. Pure argon protection, the argon flow rate is 100ml/min, the results are shown in Figure 8. It can be seen from the figure that at room temperature, the CTE of the alloy is 15.7×10^-6 K^-1 ; at 673K, the CTE of the alloy is 28.9×10^-6 K^-1 ; the alloy material is between 298 and 373K. The average thermal expansion coefficient in the temperature range is 18.9×10^-6 K^-1 .

以上所述仅为本发明的较佳实施例而已，并不以本发明为限制，凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明的保护范围之内。The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims

1. The novel low-expansion binary magnesium alloy is characterized by comprising the following components in percentage by mass: 1.6-15.5% of Gd, and the balance of magnesium and inevitable impurity elements; the thermal expansion coefficient of the magnesium alloy at room temperature is 15.7 multiplied by 10^-6K^-1～16.4×10^-6K^-1。

2. The novel low-expansion binary magnesium alloy as claimed in claim 1, wherein the magnesium alloy comprises the following components in percentage by mass: 1.6-5% of Gd, and the balance of magnesium and inevitable impurity elements.

3. The novel low-expansion binary magnesium alloy as claimed in claim 1, wherein the magnesium alloy comprises the following components in percentage by mass: 10-15.5% of Gd, and the balance of magnesium and inevitable impurity elements.

4. A preparation method of the novel low-expansion binary magnesium alloy as claimed in any one of claims 1 to 3, characterized by comprising the following steps:

1) taking a pure magnesium ingot and a magnesium gadolinium intermediate alloy as raw materials, and calculating the ingredients according to the mass percentage of the components;

2) preheating weighed raw materials, heating a preheated pure magnesium ingot to 720-750 ℃ under a dynamic protective atmosphere, melting to obtain a magnesium melt, adding a preheated magnesium-gadolinium intermediate alloy, and preserving heat for 15-20 min to obtain a magnesium alloy melt;

3) fully stirring the magnesium alloy melt obtained in the step 2), keeping the temperature at 720-750 ℃, standing for 10-15 min, then injecting the magnesium alloy melt into a preheated metal mold, cooling to room temperature, and demolding to obtain a magnesium alloy ingot;

4) putting the cast ingot obtained in the step 3) into a heat treatment furnace for solution treatment to obtain the magnesium alloy with evenly distributed Gd element, namely the low-expansion binary magnesium alloy.

5. The method for preparing the novel low-expansion binary magnesium alloy as claimed in claim 4, wherein the protective atmosphere is CO₂And SF₆The mixture ratio of the mixed gas is 99: 1.

6. the method of preparing the novel low expansion binary magnesium alloy of claim 4, wherein the magnesium gadolinium intermediate alloy is Mg-30 wt.% Gd.

7. The preparation method of the novel low-expansion binary magnesium alloy as claimed in claim 4, wherein the preheating temperature is 200-250 ℃.

8. The method for preparing the novel low-expansion binary magnesium alloy as claimed in claim 4, wherein the temperature of the solution treatment is 500-520 ℃ and the time is 12-18 h.

9. Use of the novel low-expansion binary magnesium alloy as defined in any one of claims 1 to 3 in the preparation of repair welding materials or electronic component materials.