Experimental Investigation on Laser Impact Welding of Fe-Based Amorphous Alloys to Crystalline Copper

Abstract

Recently, amorphous alloys have attracted many researchers’ attention for amorphous structures and excellent properties. However, the welding of amorphous alloys to traditional metals in the microscale is not easy to realize in the process with amorphous structures unchanged, which restrains the application in industry. In this paper, a new method of welding Fe-based amorphous alloys (GB1K101) to crystalline copper by laser impact welding (LIW) is investigated. A series of experiments was conducted under different laser energies, during which Fe-based amorphous alloys and crystalline copper were welded successfully by LIW. In addition, the microstructure and mechanical properties of welding joints were observed and measured, respectively. The results showed that the surface wave and springback were observed on the flyer plate after LIW. The welding interface was straight or wavy due to different plastic deformation under different laser energies. The welding interface was directly bonded tightly without visible defects. No visible element diffusion and intermetallic phases were found in the welding interface. The Fe-based amorphous alloys retained amorphous structures after LIW under the laser energy of 835 mJ. The nanoindentation hardness across the welding interface showed an increase on both sides of the welding interface. The results of the lap shearing test showed that the fracture position was on the side of copper coil.

Simulation and Experimental Comparison of Laser Impact Welding with a Plasma Pressure Model

“…Considering that the experiments include an initial standoff distance between the two foils, and because of the 3D Gaussian profile of the ablation pulse pressure, the generation of a gap that gradually increases with position away from the center of the weld might be expected. However, as seen in Figure 10, starting from the center of the weld, and moving away in the radial direction, the gap gradually increases to a maximum and then starts decreasing, resulting in a shape very similar to the springback region reported in the literature [24,[30][31][32][33][34][35][36]. Although similar in shape, these are two different phenomena and they happen for different reasons; the annular gap observed in these experiments is attributed to the Gaussian profile of the laser-induced plasma pulse pressure, and the size of the double-sided tape attached to the flyer's laser-ablated area.…”

“…Sample images for the case with a laser fluence of 31.08 J/cm 2 and a standoff distance of 0.26 mm are shown in Figures 10 and 11. As mentioned in Section 2, in most LIW experimental results reported in the literature, due to very high flyer impact velocities and very low impact angles, springback occurs and welding is not achieved in the center of the laser-ablated region [24,[30][31][32][33][34][35][36]. This is an unwanted event which decreases the strength and integrity of the weld.…”

“…Consequently, the thin flyer plate is launched with high-velocity distribution towards the target plate. In some cases, as reported in the literature [24,[30][31][32][33][34][35][36], upon collision, bonding is not achieved near the center of the ablated spot since the impact angle is zero and the impact velocity is too great. Instead, the flyer plate (and sometimes also base plate depending on the boundary conditions) springs back.…”

“…Therefore, overall the bond strength was increased with increasing laser fluence. In another experimental work, the authors achieved LIW of 0.03 mm thick crystalline copper flyers to 0.028 mm thick Fe-based metallic glass targets [34]. Copper foil was annealed and attained a finer grain structure prior to LIW.…”

Effects of Pulse Parameters on Weld Microstructure and Mechanical Properties of Extra Pulse Current Aided Laser Welded 2219 Aluminum Alloy Joints

“…However, the shortcomings of the laser welding process involve the high price of the laser equipment, the instability of the process, and the probability of crack and pore defects, especially while laser welding highly-reflective material, such as aluminum alloy [1,2,3]. In past decades, for the purpose of the mitigation of the above problems, and wider application of laser welding, external electric or magnetic fields have been used to aid laser welding in the investigations.…”