Bi-Sn熔体在高熵合金上的润湿行为及界面特征

Wetting behavior and interfacial characteristics in the molten Bi-Sn/ high-entropy alloy system

摘要:

采用传统座滴法研究了低熔点合金(Bi-Sn)和高熵合金(AlCoFeNiCr和CuCoFeNiCr)之间的润湿行为及界面特征。借助扫描电镜(SEM)和能谱分析(EDS)分析了Bi-Sn/AlCoFeNiCr和Bi-Sn/CuCoFeNiCr界面微观结构。结果表明：AlCoFeNiCr和CuCoFeNiCr高熵合金都是结构单一的固溶体,但Bi-Sn熔体在CuCoFeNiCr高熵合金基体上的润湿性明显地优于Bi-Sn熔体在AlCoFeNiCr高熵合金基体上的润湿性；Bi-Sn/CuCoFeNiCr界面发生剧烈的化学反应,有大量的界面反应物生成,Bi-Sn熔体中的原子Sn主要是沿着CuCoFeNiCr高熵合金中的富铜相扩散,而Bi-Sn/AlCoFeNiCr界面平直,且随着润湿温度的升高,Bi-Sn熔体中的原子向AlCoFeNiCr高熵合金基体的扩散程度加强并伴随化学反应,出现类似“皮下潜流”现象；由于CuCoFeNiCr高熵合金中富铜相的存在,为Bi-Sn在CuCoFeNiCr高熵合金基体上的铺展提供了“润湿通道”.

Abstract:

High entropy alloys (HEAs) formed with simple crystal structures such as FCC and BCC have been reported exhibiting superior tensile or compressive properties, resistance to wear, high thermal stability. However, few works were carried out on the wettability of the molten metals on HEAs substrate. And the general objective of this work is to better understand the wettability of the molten metals on the HEAs substrate. Bi-Sn alloy with the low melting point and the AlCoFeNiCr HEA and the CuCoFeNiCr HEA were selected as experiential materials. By the sessile drop method, the wetting behavior and the interfacial characteristics of the molten Bi-Sn on the AlCoFeNiCr HEA and the CuCoFeNiCr HEA substrate were investigated. The scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS) was used to analyze the microstructure the Bi-Sn/AlCoFeNiCr HEA and Bi-Sn/CuCoFeNiCr HEA interface. The results show that the AlCoFeNiCr HEA and the CuCoFeNiCrHEA form with a single solid solution structure. However, Bi-Sn molten alloy on CuCoFeNiCr HEA substrate has better wetting characteristics than Bi-Sn molten alloy on AlCoFeNiCr HEA substrate. With increasing wetting temperature, a number of intermetallic compounds existed at the interface between the molten Bi-Sn and the CuCoFeNiCr HEA substrate, and the diffusion of Sn atom along the Cu-rich solid-solution phase in CuCoFeNiCr HEA is much more intense. On the contrary, interface of the Bi-Sn/AlCoFeNiCr HEA system is still the straight interface, and there are new intermetallic compounds on the Bi-Sn/AlCoFeNiCr HEA interface with increasing wetting temperature. It is found that the Cu-rich phase in CuCoFeNiCrHEA provides a “wetting channel” for the wetting process between the molten Sn and CuCoNiFeCr HEA substrate, which result in the two wetting systems with different wetting mechanism.