Investigation on Strength and Microstructural Evolution of Porous Cu/Cu Brazed Joints Using Cu-Ni-Sn-P Filler

Abstract

Porous Copper (Cu) was brazed to Cu plates using Cu-9.7Sn-5.7Ni-7P amorphous filler metal. The effects of brazing parameters on the porous Cu and brazed joints were investigated. The furnace brazing temperatures employed were 660 °C and 680 °C, and the holding times were 10 and 15 min. After brazing, the microstructure was analyzed using Scanning Electron Microscope (SEM) equipped with Electron Dispersive X-ray Spectroscope (EDS). SEM results showed that the thickness of the brazed seam at the base joint decreased with increasing temperature and time. At low brazing temperature, microvoids and cracks were observed at the joint interface. The microvoids and cracks disappeared in the sample brazed at 680 °C for 15 min, and higher diffusion of the filler was noted in the overall bonded region. The formation of Cu-P, Cu-Ni, and Ni-Sn phases at the joint interface was validated using X-ray diffraction. The phases formed increased the hardness of the brazed joints and porous Copper. It was observed that the rigidity of porous Copper tends to increase due to surface hardening effects. The rigidity of porous Cu after brazing is important in ensuring minimal deformation during cooling device servicing, which is an integral feature of prospect product development.

Interfacial microstructure and strength of brazed copper/porous copper foam towards the effect of porous copper foam pore density and brazing holding time

“…The filler was found to diffuse and coat more on 50 PPI of porous copper foam branch rather than accumulate in the brazing seam region. Similar behaviour of filler diffusion onto the branch of porous copper foam has been reported [22]. The 50 PPI of porous copper foam owns a small branch size has enhanced the filler to spread onto the porous copper foam branch.…”

“…The filler region on the porous copper foam proved the filler able to diffuse and immigrate on the branches of porous copper foam. Prolong brazing holding time also has improved the filler wettability and spreading [22]. The filler tends to immigrate and diffuse onto porous copper foam via capillary action at a long duration of brazing holding time.…”

Deformation and Fracture Behavior of Sandwiched Copper Foam Brazed Joint Using Amorphous Copper–Tin–Nickel–Phosphorus Filler

“…The diffusion of P and Ni elements into the foam allows it to coat the foam branches and leads to the increase in foam strength. Similar phenomenon was found by Sami et al (2020). Authors investigated the sandwiched Cu foam brazing using a single layer of Cu-9.7Sn-5.7Ni-7P foil at 680°C for 15 min.…”

Hydrogen Bubble-Assisted One-Step Electrodeposition of Cu, Ni, and P toward Electrocatalytic Water Oxidation

“…The diffraction peaks located at 2θ values of 43.5, 50.6, 74.4, and 89.9 in the XRD patterns are perfectly indexed to the (111), (002), (022), and (113) planes of electrodeposited Cu 3.8 Ni 0.2 (labeled as “*”) along with electrodeposited Cu and substrate Cu sheet (labeled as “#”) (JCPDS card no. 98-008-7506, 98-008-7360), suggesting the successful insertion of Ni with Cu to form the Cu 3.8 Ni 0.2 alloy irrespective of the Cu and Ni ratio in the electrodeposition solution. , The peak intensity corresponding to a 2θ value of 89.9 corresponding to the Cu substrate electrode is found to be suppressed with the increase of the Cu vs Ni content in the electrodeposition solution, which can be attributed to the increase of deposition of the film on the substrate, as Cu is well known to deposit and form metal architecture relative to other metals . Previous studies have shown that with the decrease of the Cu composition in the Cu–Ni electrodeposition solution, the phase of the depositing alloy does not change, which is also evident in our case …”