Effects of Pulse Current on Transient Liquid Phase (TLP) Diffusion Bonding of SiCp/2024Al Composites Sheet Using Mixed A
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C particle-reinforced aluminum matrix composites with high specific strength and good wear resistance are widely applied in airplanes, the aerospace industry, and the vehicle industry.[1,2] In order to extend the practical applications of SiCp/Al composite sheets further, the investigation on suitable joining techniques is urgent and important. Pulse current auxiliary transient liquid phase (TLP) diffusion bonding is derived from TLP diffusion bonding,[3] spark-plasma sintering,[4,5] resistance heating,[6] and pulse current auxiliary sintering.[7] The specific feature of this technique is the application of a high-intensity pulse current in the diffusion bonding process. Similar to the technique above, this technique also has many advantages, including a quick heating rate, lower energy cost, the local heating, small plastic deformation, etc. In this work, we studied the pulse current auxiliary TLP diffusion bonding of SiCp/2024Al composites sheet using a mixed slurry of an Al, Cu, and Ti powder interlayer. This study focuses on the effects of pulse current on the bonding mechanism, microstructure, and mechanical performance.
BO WANG, Ph.D. Student, SHAOSONG JIANG, Instructor, and KAIFENG ZHANG, Processor, are with the National Key Laboratory of Science and Technology on Precision Heat Processing of Metal, Harbin Institute of Technology, Harbin 150001, P.R. China. Contact e-mail: [email protected] Manuscript submitted April 3, 2012. Article published online July 10, 2012 METALLURGICAL AND MATERIALS TRANSACTIONS A
A 17 vol pct SiCp/2024Al composite sheet was cut to 25 9 10 9 1.5 mm. The powder interlayer was used by coating a mixed slurry of Al, Cu, and Ti powder (2:1:1) on the cross area of the specimen. The particle sizes of Al, Cu, and Ti powders were 43 lm, 74 lm, and 43 lm, respectively. The bonding surfaces were carefully ground and cleaned in acetone in order to reduce oxide layer and impurity. The experiments were performed at 853 K (580 C) for 15 to 60 minutes. The process parameters were as follows: the pulse current density of 1.15 9 102 A/mm2, the original pressure of 0.5 MPa, and the vacuum of 1.3 9 10 3 Pa. Figure 1 shows the schematic diagram of stack manner and device. The cross area of both specimens was 2 mm. The insulated mica layers make pulse current getting only through the joint. The temperature was measured using an infrared thermometer, which fed back the digital signal to the monitor meter. Pulse current auxiliary TLP diffusion bonding of SiCp/2024Al composite sheet was successfully carried out at 853 K (580 C) using a mixed slurry of an Al, Cu, and Ti powder interlayer. The joints almost have no bulk deformation because of the lower temperature and pressure. The backscattered electron images show that the dense joint without a cavity is formed in Figure 2(a). An energy-dispersive X-ray spectroscopy (EDS) line profile in Figure 2(c) shows that the Ti mainly distribute in the interlayer and Cu happens to diffuse from the powder interlayer to the Al substrate. The maximum concentration peak in t
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