Composite Filler Metals for Joining Temperature-Sensitive Aluminium- Matrix Composites

Abstract

Lightweight composite materials like aluminium-matrix composites (AMC) have been applied in many different sectors such as aerospace industry, automobile production, or power-electronics. As a special group of composites, AMCs produced by ECAE (equal-channel angular extrusion) feature a very high strength due to a very fine-grained structure. But they are very temperature-sensitive. Therefore, an adapted joining technique is required. In this regard, soldering offers some advantages in comparison to other joining processes like welding or bonding. Because of their low melting range below 300 °C, Sn-based filler metals are suitable for this purpose; Ag and Cu are the common alloying elements. The low strength and creep resistance of the joints are disadvantageous features. By the development of Sn-based composite fillers, an improvement of these properties can be achieved due the addition of ceramic reinforcing particles like Al2O3 or SiC. Investigations into the formation of an interfacial reaction layer between reinforcing particles and filler matrix were carried out. Ti as active element was alloyed to improve the bonding between matrix and particles. The microstructure observed by SEM has been correlated with the results of the tensile tests.