Page 63 - ESAM-1-4

Engineering Science in
Additive Manufacturing EST manipulates structure of Ti-6Al-4V/Cu

strength of copper-based composites without causing a However, no systematic studies have been reported
significant decrease in electrical conductivity. 13-15 on the microstructural evolution and texture effects of
LMD enhances interfacial bond strength by promoting Ti-6Al-4V/Cu-Cr-Zr interfaces fabricated by LMD using
mixed diffusion of copper and coating material, while EST. Therefore, in this study, we prepared Ti-6Al-4V/
leading to significant amounts of copper entering the Cu-Cr-Zr by using LMD technology and investigated
coating. As a result, there are limitations in terms of changes in microstructure and mechanical properties
compatibility between the metal substrate and the cladding under high-energy-density current conditions. This
material. Other scholars have also conducted extensive research provides theoretical guidance and experimental
research in this area. For instance, Li et al. deposited support for enhancing the performance of copper-based
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AlCrFeNiMnx high-entropy alloy on a copper substrate composites.
and found that an increase in Mn improved the copper 2. Materials and methods
diffusion coefficient, facilitating diffusion of copper into
the cladding layer and thus reducing the hardness of the 2.1. Materials preparation
cladding layer. By depositing CoCrNiFeTix high-entropy In this work, a Cu-Cr-Zr alloy was used as the substrate,
alloy on the copper alloy surface, Jia et al. demonstrated with its main composition shown in Table 1. The substrate
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that the hardness of the cladding layer increased with the sample dimensions were 43 mm × 32 mm × 7 mm. Five
addition of Ti content. CoCrW-xCu coatings with good pieces of Cu-Cr-Zr material were prepared for LMD.
metallurgical bonding were prepared by laser cladding Before the LMD experiments, the substrate underwent
by Dong et al. Zhou et al. achieved laser cladding of a pre-treatment: First, surface oxide layers were removed by
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gradient molybdenum coating on copper alloy surfaces. grinding with 600# and 1200# sandpaper. Subsequently,
By adjusting process parameters, they obtained well- the Cu-Cr-Zr substrate surface underwent shot peening
bonded, defect-free, and dense strengthening layers. Shear to reduce surface gloss and enhance surface roughness. In
tests evaluated the bond strength, with maximum values preliminary work, we thoroughly investigated the influence
reaching 240 MPa. The above-mentioned studies have all of surface roughness on the LMD coating properties under
achieved effective strengthening of copper alloy surfaces, various shot peening parameters. Detailed comparisons
thereby enhancing their surface properties. of interface forming performance across six distinct
As a rapid post-processing technology, electroshock Ra values revealed that a coating with optimal forming
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treatment (EST) optimizes the organizational structure of characteristics was achieved at Ra = 3.9 μm. Consequently,
the material through the action of high current, offering all subsequent LMD experiments were conducted with a
a novel approach to enhancing material properties. surface Ra maintained at 3.9 μm. Finally, acetone cleaning
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EST provides favorable conditions for analyzing the was performed to remove oil contamination from the
microstructure evolution of the bonding zone of the substrate surface, followed by ultrasonic cleaning with
composite layer under high current density. 21-23 Fan anhydrous ethanol to eliminate adhering contaminants
et al. investigated the effect of electrical pulse on the and particulates. The substrate was dried and set aside
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microstructure of spot welded joints of AA2198-T8 for later use. Ti-6Al-4V powder with a particle size of
aluminum alloy. The interfacial defects of the welded 45–150 μm was selected as the coating material, with its
joints were gradually reduced with the increase of the main composition shown in Table 1. The powder exhibits a
electrical pulse time. Liu et al. explored the defect spherical morphology with excellent sphericity, with 80%
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healing mechanism of 6061-T6 aluminum alloy under of the particle size distribution ranging from 69 to 117 μm.
electrical pulse, and found that the current bypassing the The coating was prepared via LMD in an argon atmosphere
holes would produce local current density increase and with oxygen content below 100 ppm, as illustrated in
Joule heat effect around the holes, and the holes would Figure 1A. LMD experiments were conducted using an
be deformed and healed under the action of thermal LMD 16080 system (Nanjing Zhongke Raycham Laser
compression stress. Qian et al. performed EST on the Technology Co., Ltd., China), with a YLS-2000 laser source
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interface of stainless steel joined in hot compression (IPG Photonics) operating at 1800 W. The powder feed rate
and found that EST promoted recrystallization at the
interface and the formation of fine equiaxed crystal Table 1. Chemical composition of Cu‑Cr‑Zr substrate and
grains, which contributed to the healing of the interface. Ti‑6Al‑4V powder (wt.%)
Taken together, EST induces the microstructure variation Materials Cr Zr Cu Al V C N O Fe Ti
of the material, and such microstructural changes are
closely related to the compression, tensile, and fatigue Cu-Cr-Zr 1.03 0.11 Bal. - - - - - - -
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life of the material. 29,30 Ti-6Al-4V - - - 6.2 4.15 0.01 0.015 0.15 0.056 Bal.
Volume 1 Issue 4 (2025) 2 doi: 10.36922/ESAM025430030