Abstract Metal matrix composites were made by infiltrating liquid metal under high pressure into an alumina platelet preform. The preform cracked during infiltration. To understand this behaviour, the mechanical properties of the preform have been studied. The brittle behaviour observed during bend tests could explain the failure of the preform during infiltration. 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 calculate the percentage of fibres needed to reach a controlled failure behaviour, which prevents damage during infiltration. Good results were obtained with a hybrid preform containing a fibre weight fraction of 35%.