Interfacial characteristics for brazing of aluminum matrix composites with Al-12Si filler metals

Abstract

Discussions concerning the interfacial reactions and characterizations in brazing aluminum matrix composites are documented in this study. Joints of alumina particulate reinforced 6061 aluminum matrix composites were made using an Al-12 (wt pct) Si filler metal by vacuum brazing. The resulted maximum bonding strengths were 75.4, 81.5, and 71.8 MPa for 10, 15, and 20 vol pct alumina reinforcement, respectively. The microstructural examinations revealed that the bonding strength was strictly related to the reinforced alumina particles and the reaction products presented at the joint interfaces. During brazing, Mg segregated at the joining interface and alumina/6061 Al interface. Further, reactions between alumina and 6061 Al matrix resulted in the formation of Mg-rich phases, such as MgAl 2 O 4 and MgO, near the joining interface and the alumina reinforcement. The Si in the filler material penetrated into the metal matrix composites (MMCs) matrix and segregated at the alumina/6061 Al interfaces. This phenomenon can be confirmed by a joint between two alumina bulk specimens.

Vacuum brazing of aluminium metal matrix composite (55vol.% SiCp/A356) using aluminium-based filler alloy

“…4a and b). Such voids were also found when brazing of Al-MMCs containing alumina particles [10]. So it was concluded that the wettability of filler metal on SiC particles is not always good when brazing at 550 • C. With the brazing temperature raised to 560 • C, the flowability and activity of the filler metal were substantially improved (Fig.…”

“…Although researchers [10,11] have investigated the joining of Al-MMCs reinforced with low volume fractions of reinforcements by direct brazing and the results are reasonably good, the direct brazing of Al-MMCs reinforced with high volume fractions of reinforcements have not been reported. In this work, an Al-Cu-Mg-Si-Ni alloy was used as the filler metal to braze an Al-MMC with a high volume fraction of SiC particles.…”

Problems of aluminum foam soldering

“…A great affinity of aluminum for oxygen requires that aggressive fluxes be used to remove a layer of oxides Al 2 O 3 from the specimen surface before soldering [10][11][12][13].…”

Microstructural characteristics and formation mechanism of friction stir welds of SiC particulates reinforced Al–Si matrix composites

“…Particulates reinforced aluminum matrix composites (PRAMCs) exhibit high specific stiffness and strength to weight ratio at room and elevated temperatures, and thus possess potential structural applications in the aerospace and automotive industries [3]. However, it is difficult to achieve high-performance joints of PRAMCs by using conventional fusion welding, brazing and transient liquid phase diffusion welding (TLP-DW) [4][5][6][7]. The previous researches on FSW indicated that the joint efficiency of PRAMCs was between 80% and 97% [3,8].…”