Titanium as an Activator Material for Producing MMCs by Pressureless Melt Infiltration

摘要

For the fabrication of MMCs (Metal Matrix Composites), the infiltration behaviour of metallic melts in ceramic substrates is decisive. The use of titanium in pressureless reactive melt infiltration for some ceramic/alloy combinations is currently of considerable interest. Since most ceramics are only poorly wetted by metal melts, an activating element such as titanium or chromium is needed. It is still not known whether the improvement of wetting, and thereby infiltration, is due to the formation of a reaction layer on the ceramic by the active element, or whether titanium is only necessary to promote the beginning of the infiltration process, which may then proceed further via gravitational and capillary forces. In order to improve the understanding of the infiltration process, time-dependent infiltration experiments have been performed and the obtained microstructures and ceramic-metal nterfaces characterized.