Pulse laser processing of a SiC/Al-alloy metal matrix composite

Abstract

The microstructural changes and the tensile behavior of laser processed A356-A1 alloy matrix composites reinforced with 10 and 20 vol. % SiC particulates are characterized. The autogenous bead-on-plate welds were made using a pulsed CO 2 laser operating at a peak power level of 3.2 kW. The pulse on-time was constant at 20 ms and the off-time was varied from 20 to 2 ms (duty cycles of 50-91%). The microstructure of the laser melted region was investigated by optical, scanning, and transmission electron microscopy, and x-ray microchemical analysis techniques. The extent of microstructural changes varied directly with duty cycle, i.e., being a maximum for the longest (91%) duty cycles. Pulsed laser processing produced partial to complete dissolution of SiC particles and sometimes resulted in the formation of aluminum carbide. The associated rapid cooling also produced a fine distribution of nonequilibrium complex precipitates. In addition, the laser energy modified the SiC surface both physically and chemically. The results of tensile tests indicated that the modified SiC and the distribution of fine nonequilibrium precipitates enhance the mechanical properties of the laser processed composites. Optimum changes in microstructure and mechanical properties were obtained in the composites processed with intermediate (67 and 74%) duty cycles; therefore pulsed processing appears to be a strong candidate for successful joining of these MMCs. 514

Microstructure and wear studies of laser clad Al-Si/SiC(p) composite coatings

“…As a result, Al 4 C 3 and Al 4 SiC 4 may also precipitate directly from the C and Si enriched Al-based melt formed [12]. The presence of Al 4 Si 2 C 5 carbide has been reported by Dahotre et al [13] in pulsed laser welding of SiC/Al-alloy composites and by Liechti [14] that observed the presence of both Al 4 SiC 4 and Al 2 SiC 5 in Al-Si/SiC coatings produced by laser cladding. However, Al 4 Si 2 C 5 was not found in the detailed and extensive study carried out by Viala et al [6] and Oden et al [12] and controversy exists about the formation of this carbide.…”

Fusion and friction stir welding of aluminum-metal-matrix composites

“…This shows that the energy density plays an important role in the deterioration of reinforcements. In addition, other work has shown that, even in laser welds with a high energy density, [4,24] pulsing will reduce the tendency toward the formation of carbides. Since the peak temperature of the molten pool is related to the energy density, one can envision that the deterioration is directly linked to the temperatures achieved in the weld pool.…”

“…[1,2] In the past, fusion welding, diffusion bonding, resistance welding, and friction welding have been used to evaluate the feasibility of joining these materials. [1][2][3][4][5][6][7][8][9][10][11][12][13] Among the fusion-welding processes, the arc, electron beam (EB), and laser beam (LB) methods have been considered, with and without filler wire. Resistance spot welding was performed, with and without a soft aluminum interlayer.…”

“…[13] During laser welding, it is very difficult to avoid these decompositions. However, Dahotre et al, [4] in their elegant work, showed that decreasing the specific energy during laser melting could reduce the formation of Al 4 C 3 . Based on these two works and on other published research on Al-SiC composite welding, one can speculate that the tendency to form these Al 4 C 3 carbides can be related to peak temperatures achieved in the melt, i.e., a low specific energy leads to less superheating above the melting point of the aluminum alloy.…”

Review on experimental study of Nd:YAG laser beam welding, with a focus on aluminium metal matrix composites

“…Authors have also carried out an autogenous bead-onplate welding experiment of A356 alloy reinforced with SiCp 10 and 20 vol% using pulsed CO 2 laser at 3.2 kW peak power to study the microstructure and determine the mechanical properties of the weldment. Dahotre et al [19], in their study carried out mechanical testing using Instron tensile testing machine. Both optical microscopy and analytical electron microscopy were used for microstructure characterization.…”