The effect of fabrication processes on the mechanical and interfacial properties of SiCf/Cu-matrix composites

Three groups of SiCf/Ti/Cu composites were prepared under conditions of 650 degrees C + 105 min (sample 1#), 750 degrees C + 85 min (sample 2#) and 840 degrees C + 50 min (sample 3#), respectively, by foil-fiber-foil method (FFF), and their room temperature tensile strengths were established. The aim is to model the reactive bonding states between Ti and SiC fiber and between Ti and Cu when Ti is used as interfacial adhesion promoters in SiCf/Cu-matrix composites. The fracture surfaces, SiCf/Ti interfaces and Ti/Cu interfaces were investigated by scanning electron microscopy (SEM), optical microscopy and energy dispersive spectroscopy (EDS). The tensile tests show that the tensile strengths of samples 1# and 2# are not obviously enhanced due to the weak bonding strength between SiC fiber and Ti, while those of sample 3# are achieved above 90% of ROM (the rule of mixtures) strength because of excellent bonding between SiC fiber and Ti. However, there are distinct Ti/Cu interfacial reaction zones after the three processes, which are approximately 5.4, 9.0 and 13.3 pm thick, respectively. The Ti/Cu interfacial reaction products are mainly distributed in four layers. In samples 1# and 2#, the products are predicted to be Cu4Ti, Cu3Ti2, CuTi and CuTi2 according to their chemical compositions determined by EDS, while in sample 3#, the products are Cu4Ti, Cu4Ti3, CuTi and CuTi,. Additionally, the relationships between the thickness of Ti interlayer and its reaction with C and Cu are also discussed, and an optimal thickness of Ti is introduced. (c) 2007 Elsevier Ltd. All rights reserved.