Abstract: An apparatus for mixing a particulate substance, which may be in chopped or short fibre form, with a matrix metal comprises a container (11) for molten metal (10) having an aperture (12) through which a stream of the metal can fall, a feed motor (20) for feeding the particulate substance into the metal stream, and one or more downwardly inclined nozzles (23) through which jets of atomizing gas are directed on to the combined flow of metal and particulate substance. The feed motor comprising a horizontal ring (20a) which extends about and is coaxial with the molten metal stream, and which has a radial vibration imparted to it so as to form a node on the axis of the ring. The upper surface of the ring may be horizontal or may be inclined downwardly towards the axis and may have annular grooves of ratchet tooth section with the steeper part of the section facing towards the axis.