IMPROVEMENT OF HIGH-PRESSURE INFILTRATION BEHAVIOR OF ALUMINA PLATELET PREFORMS - MANUFACTURE AND CHARACTERIZATION OF HYBRID PREFORMS

Metal matrix composites were made by infiltrating liquid metal under h igh pressure into an alumina platelet preform. The preform cracked dur ing infiltration. To understand this behaviour, the mechanical propert ies of the preform have been studied. The brittle behaviour observed d uring bend tests could explain the failure of the preform during infil tration. This brittle behaviour was overcome by mixing fibres with the platelets. The manufacturing process and the mechanical properties of such hybrid preforms have been studied in order to get the percentage of fibres needed to reach a controlled failure behaviour, which preve nts damage during infiltration. Good results were obtained with a hybr id preform containing a fibre weight fraction of 35%. (C) 1998 Elsevie r Science Limited. All rights reserved.