摘 要

非晶材料具有高强度、高硬度、耐腐蚀、耐磨损、优良的软磁性等特性，是20世纪材料领域最重大的发现之一，在精密机械、信息、航空航天、医疗、国防工业、汽车工业、化学工业等领域有重要的应用价值。Zr基非晶合金是非晶合金中最早被发现和研究较成熟的体系之一，近年来受到越来越多研究人员的关注。但由于非晶合金制备过程中需要急冷且要求高真空环境，通常制备的非晶合金材料尺寸较小，这极大地限制了非晶材料在工程领域的应用。若能通过合适的焊接工艺对非晶合金进行焊接，不仅可免受制备工艺的限制，一定程度上还能增大非晶合金尺寸，充分发挥Zr基非晶合金优异性能的优势。

超声波辅助钎焊可在低温实现对Zr基非晶材料的连接。空化作用可有效增加熔融钎料在母材金属表面的润湿，优化焊缝组织，促进界面反应。通过设定合理的焊接参数，超声波辅助低温钎焊可避免焊接过程中Zr基非晶材料发生结构弛豫与晶体化，达到良好的焊接效果。本实验以镍泡沫增强锡为填充材料，300℃对Zr基非晶材料表面镀锡，再将其加热到300℃使锡熔化，加入超声波作用将两块同质Zr非晶材料连接在一起。研究了镀锡时间对Zr基非晶合金与Sn冶金反应的影响以及超声波工艺在Zr基非晶合金焊接过程中的作用。结果表明，随着镀锡时间增加，Zr基表面镀锡层厚度逐渐增加，气孔逐渐减少。不同镀锡时间下通过超声波辅助钎焊得到的接头上表面未发现明显未焊合区域，镀锡时间长的钎焊接头中间层气孔少，且接头下表面未焊合区域较少。

关键词：非晶合金；超声波辅助钎焊；界面反应；未焊合区域

Abstract

Metallic glasses with high strength, high hardness, corrosion resistance, abrasion resistance, excellent soft magnetic properties and some excellent features, were one of the most important discoveries in material in the 20th century, which have a vital application value in the precision machinery, information, aerospace, medical field, defense industry, automobile industry, chemical industry and other fields. Zr-based metallic glasses which were first found as one of the most mature systems, have been raising more and more attention of the researchers in recent years. However, the application of metallic glasses in engineering has been greatly limited because of its small size caused by the preparation requirements that they should be cooled fast in a high vacuum environment. Proper welding methods can be applied to join the amorphous materials to increase the size of the metallic glasses to a certain extent and free it from the restrictions of preparation requirements in some way，thus better realizing its application value in the engineering field.

Ultrasonic assisted brazing can join Zr-based amorphous material in low temperature. The cavitations can effectively enhance the wetting of molten solder on the base metal, as well as optimize the microstructure and promote interfacial reaction. By setting reasonable welding parameters, A sound bonding without structural relaxation and crystallization can be achieved by employing ultrasonic assisted brazing in low temperature. In this paper, filler materials were Sn foamed nickel, Tin was plated on the surface of Zr-based amorphous material at 300℃ in different time. Then they were remelted and Zr-based amorphous materials were joined together under ultrasonic. Metallurgical reaction characteristics between Zr-based amorphous material and Sn alloy in different Tin plated time, as well as the effect of ultrasonic welding in the process of joining Zr-based amorphous material were investigated. The results showed that with the increase of time , the thickness of tin on Zr-based surface gradually increased, while the stomata decreased. Un-welding zone wasn’t found on the upper surface of the joint obtained by ultrasound-assisted brazing. What’s more, both the stomata on the solder layer and the un-welding zone on the lower joint surface were less when Tin was plated under a longer time.

Key Words: metallic glasses, ultrasonic assisted soldering, interfacial reaction, un-welding zone

目 录

摘 要 I

Abstract II

1 绪论 1

1.1 课题研究的目的及意义 1

1.2 非晶合金的焊接性 3

1.3非晶材料焊接研究现状 3

1.4 本课题主要研究内容 9

2 实验材料与工艺 10

2.1实验材料及仪器 10

2.1.1实验材料 10

2.1.2 实验设备 10

2.2 实验过程 11

2.2.1 焊前准备 11

2.2.2 焊接过程 13

2.2.3 金相试样的制备 13

2.2.3 显微组织的观察 15

3 结果与讨论 16

3.1 Zr基非晶表面低温镀锡界面特征 16

3.2 焊缝微观金相分析 17

4 实验总结与展望 22

4.1 实验结论 22

4.2 研究展望 22

参考文献 23

致 谢 24

1 绪论

1.1 课题研究的目的及意义

非晶合金与一般晶体结构材料不同。它的原子排列无序，类似于玻璃结构，但又与一般玻璃不同，具有良好的导电性和优异的软磁性。由于其没有晶体结构和位错缺陷，强度较高，为制备新型高强度合金提供了一条新途径。非晶合金与晶态合金内部原子排列示意图如图1-1所示^[1]。

图1-1 非晶态合金（左）与晶态合金（右）原子排列示意图^[1]

1960年，W. Klement (Jr.), Willens 和 Duwez等人通过急速冷却（冷速10⁶K/s）制得的Au₇₅Si₂₅是最早被报道的非晶态合金。但由于冷速限制，只能制成薄带、箔片和丝线形状，因此非晶态合金在实际应用中也受到一定限制。1976年，H. Liebermann 和 C. Graham发明了甩带法制备薄片状非晶态合金的新工艺。用这种工艺制备的含Fe、Ni、P、B元素的非晶合金具有很低的磁损耗，在室温下磁饱和强度可达到1.56T。随着科学技术的发展，制得的非晶合金的性能也更加优异。1990年，科学家研制出了临界冷却速率≦1K/s的新型非晶态合金。由于冷速的降低，可通过金属型铸造的方法来制备非晶态合金，合金的厚度可达数厘米，又称为块状非晶合金（BMG）。近年来，非晶合金材料的应用也逐渐成为研究中的热点。常用的合金中玻璃化能力最好的为Zr基和Pd基合金。

Zr基非晶合金性能优异，应用领域广，在过冷温度区间具有良好的超塑性流变特性，可用于制作形状复杂的微小部件。利用Zr基非晶材料制备的精密齿轮和轴承在应用中也表现出卓越的性能。在其他领域也有很多应用。由于磁损耗低，常被用于制备高频变压器磁芯^[1]。非晶合金在人造骨骼，组织修复和航天领域^[2]中也有较大的潜在应用价值。