There is described an apparatus for mixing solid particulates in a molten metal matrix to form a metal matrix composite, the apparatus comprising a refractory vessel (10) for containing the metal matrix in a molten state and defining an inlet (16) and an outlet (18); refractory conduit means (12) in communication with both the inlet (16) and the outlet (18) so as to define with the vessel (10) a closed loop flow path, the inlet (16) and outlet (18) being so spaced as to encourage mixing within the vessel (10); and pump means (20) disposed within the flow path and operative to circulate the metal matrix and particulates around the closed loop path so as to effect a mixing thereof. There is also described a method for mixing solid particulates in a molten metal matrix to form a metal matrix composite, the method comprising the steps of providing a refractory vessel (10) in communication with refractory conduit means (12) such that the vessel (10) and the conduit means (12) define a closed loop flow path; providing a molten metal matrix and particulates within the closed loop path; and circulating the metal matrix and particulates around the closed loop path so as to effect a mixing thereof.