Surface modifications of a hyperperitectic Zn-10 wt% Cu alloy by pulsed electron beam treatment

• Published in: Surface & coatings technology 2020-04, Vol.388, p.125530-8, Article 125530
• Main Authors: Song, L.X., Zhang, K.M., Zou, J.X., Yan, P.
• Format: Article
• Language: English
• Subjects: Copper; Copper base alloys; Corrosion; Corrosion resistance; Corrosion resistant alloys; Electron beam processing; Electron irradiation; Electron microscopy; Flux density; High current pulsed electron beam (HCPEB); Microhardness; Microscopy; Microstructure; Optical microscopy; Peritectic alloy; Pulse duration; Rapid solidification; Surface layers; Surface treatment; Zinc; Zn-Cu alloy
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2020.125530

The aim of the present work is to study the effect of High Current Pulsed Electron Beam (HCPEB) treatments on the surface microstructure and properties of a hyperperitectic Zn-10 wt% Cu alloy. The alloy samples are treated by HCPEB with an accelerating voltage of 25 kV, an energy density of 4 J/cm2, a pulse duration of 1.5 μs and pulse numbers of 5 and 15. The surface microstructure, phase components and compositions are characterized by using optical microscopy (OM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Due to the rapid solidification and cooling occurred after pulsed electron beam irradiation, the peritectic reaction ε-CuZn5 + L → η-Zn is suppressed, leading to the increased content of ε-CuZn5 in the surface resolidified layer. The polarization tests in the 3.5 wt% NaCl water solution and microhardness measurements show that the corrosion resistance is improved and microhardness increases after HCPEB treatments. In particular, the 5 pulsed Zn-10 wt% Cu alloy sample exhibits the best corrosion resistance due to the chemical homogenization, microstructure refinement and the formation of lower density of craters in the surface layer. •The peritectic reaction ε + L → η in the Zn-10wt%Cu alloy was suppressed during the HCPEB irradiation.•The content of ε-CuZn5 in the surface melted layer increases after HCPEB treatment.•The HCPEB treated layers exhibit homogeneous and refined microstructures.•The microhardness and corrosion resistance of the HCPEB treated samples are improved.•The 5 pulsed sample shows the best corrosion resistance and the maximum microhardness.