Diffusion in Ti/TiC multilayer coatings

The present communication is concerned with the interdiffusion kinetics and the local concentration variations that take place in Ti/TiC multilayer sy stem as a result of thermal anneals between 355 and 550 degreesC. Within th is temperature range, carbon is the diffusing species. Carbon diffuses from the carbide layer into the adjacent Ti layers, depleting its concentration within the former and decreasing the width of the latter. Data extracted f rom diffraction patterns allowed to determine the changes that take place i n the relative amount of the two phases as a function of time. By fitting t he experimental data to a simple model, we were able to determine the diffu sivities of carbon at different temperatures and hence, the activation ener gy, 132 kJ/moI. This value is significantly lower than expected from extrap olation of data obtained at elevated temperatures and can be attributed to the high defect content of micro-thick multilayers sputter-deposited at low temperature. (C) 2000 Elsevier Science B.V. All rights reserved.