TEM study on the microstructure of the interface at the scale of nanometer formed between Cu-8 wt.% Ti melt and C/C preform

Carbon/copper composites have been widely used in a variety of fields, for example electrical contact devices by taking advantages of both carbon and Cu simultaneously. However, the interfacial reaction and microstructure of these composites are not well known yet in the nanometer scale, especially involving the interaction between active alloy melt and carbon, which remains an important question in composites technology. In this study, we employ transmission electron microscopy (TEM) to investigate the interfacial microstructures, which are formed in the course of infiltration of carbon/carbon (C/C) composites preform by molten Cu-8 wt.% Ti at 1373 K. The results show that in the short-cut fiber web zone, there are two types of interfaces: (i) the mixture of fine-grained (FG) TiC and nano-sized Cu particles and (ii) a “Cu layer” with a thickness of no more than 500 nm at the pyrolytic carbon (PyC)/coarse-grained (CG) TiC interface. The main bonding mechanisms for the two interfaces are the formation of PyC/TiC and PyC/Cu2O interfaces, and the PyC/Cu2O interface, respectively. In the non-woven cloth zone, only Cu2O layer is found between Cu and PyC without any TiC layer due to the depletion of Ti.