High-strength diffusion bonding of oxide-dispersion-strengthened tungsten and CuCrZr alloy through surface nano-activation and Cu plating

Oxide-dispersion-strengthened tungsten(ODS-W)and a Cu Cr Zr alloy were bonded by a three-step process:(i)surface nano-activation,(ii)copper plating followed by annealing,and(iii)diffusion bonding.The morphological and structural evolutions of ODS-W and the interface of the ODS-W/CuCrZr joint during these processes have been thoroughly studied by X-ray diffraction,scanning electron microscopy,energy dispersive spectrometry,and high-resolution transmission electron microscopy.After surface nanoactivation,a nanoporous structure of ODS-W with an average pore size of~100 nm was obtained,and the Y_(2)O_(3)particles therein remained unchanged.A Cu coating was tightly bonded with the surface nanoactivated ODS-W after Cu plating and annealing.An interaction layer embedded with nanosized W particles was formed at the interface between ODS-W and plated Cu after the three-step process.Consequently,well-cohesive ODS-W/Cu and ODS-W/Y_(2)O_(3)/Cu interfaces were formed.The ODS-W/Cu Cr Zr joint showed high shear strengths(up to 201 MPa)and effective bonded area ratios(>98%).The developed three-step bonding process between ODS-W and the Cu Cr Zr alloy provides an effective support for future plasma-facing components in nuclear fusion reactor applications.

Effect of Mechanical Surface Treatment on the Bonding Mechanism and Properties of Cold‑Rolled Cu/Al Clad Plate

In the case of valuable cold-rolled Cu/Al clad plates,billet surface treatment before rolling is a significant process that can affect the bonding efficiency and quality.While the current studies primarily focus on the influence of rolling parameters,insufficient attention has been paid to surface treatment.In this study,the effects of mechanical surface treatment on the bonding mechanism and bonding properties of cold-rolled Cu/Al clad plates were investigated.The results showed that different mechanical surface treatments have significant effects on the surface morphology,roughness,and residual stress.In addition,the effect of surface mechanical treatment on bonding quality was also observed to be critical.When the grinding direction was consistent with the rolling direction(RD),the bonding quality of the Cu/Al clad plates was significantly improved.After surface treatment along the RD for 20 s,the Cu/Al clad plates showed the highest shear strength(78 MPa),approximately four times as high as that of the unpolished samples.Simultaneously,the peel strength of this process was also significantly higher than that achieved via the other processes.Finally,on the basis of the surface morphology,roughness,and residual stress,the effect of surface treatment on the bonding mechanism and bonding properties of Cu/Al clad plates was analyzed.This study proposes a deeper understanding of the bonding behavior and bonding mechanism for cold rolled clad plates processed via mechanical surface treatment.

Corrosion behavior of Cu/Al casting-rolled clad plates in different alkaline solution

The effect of pH value and different kinds of anions on the corrosion behavior of Cu/Al casting-rolled clad plates in the alkaline solution was evaluated by means of scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),weight loss analysis,3D confocal laser scanning microscopy(CLSM)and electrochemical test.Results show the corrosion mainly occurs on the aluminum side.The corrosion resistance of the Cu/Al decreases as the pH value increases.When pH≥12,the dissolution of the film layer is faster than the passivation process.The addition of Cl^(-)ions reduces the corrosion resistance of the Cu/Al clad plates,which leads to pitting corrosion.The higher the concentration of Cl^(-)ions,the more prone the pitting to occur.The addition of SO_(4)^(2-)ions causes the denudation of the samples.The corrosion resistance of the Cu/Al is better in the alkaline solution containing NO_(3)^(-)ions than that in the solution containing Cl^(-)ions or SO_(4)^(2-)ions.When adding SO_(4)^(2-),NO^(3)^(-)and Cl^(-)to the pure alkaline solution,the corrosion resistance of the Cu/Al clad plates decreases.