An Approach to Near Full Density P/M Automotive Components Liquid Phase Sintering of Iron Graphite Materials

The theses of Klein and Lam are critically reviewed/ as well as the summary paper prepared by M. Pickus, their advisor. These works suggest that transient liquid phase sintering of Fe graphite can occur with .2 to .8%C at 2150°F (1147°C) in 10 to 30′, yielding near full density, with ductility equivalent to hot rolled steel. If this can be made to work with ordinary iron powders, it will lead to a new economical process to make automotive parts. We have tried to repeat some of their work, using the present day less expensive atomized irons and the same graphite forms used by Lam. These graphites dissolve in Fe under ordinary sintering conditions, before the eutectic temperature is reached. Nonetheless, we have seen some evidence of local densification to near theoretical. This gave rise to numerous suggestions for additional work to be done.