Abstract: A fibre (1), which may be an artificial polymeric, glass or glass-fibre fibre, is treated by exposing it to an energy flux (2) so that the fibre absorbs energy differentially along its length, and the cross-section of the fibre is altered in response to the varying amounts of energy absorbed along the length of the fibre, to yield a fibre which has intermittent zones of relatively reduced cross-section. Preferably the fibre is drawn past an energy beam which is pulsed or oscillated across the fibre path. The fibre may be exposed while it is being formed by drawing it under tension from a spinneret nozzle, and is further stretched after exposure to the beam to form intermittent necks (3) in the fibre. The novel fibres may be used in textile applications or as reinforcing elements in composite materials.

Abstract: A metal stream is protected from atmospheric contamination during casting by shrouding it with an inert gas from a gas source at the pour nozzle. The gas is supplied to a low turbulence zone at the nozzle which has a width at least one third of the length of the poured metal stream. The gas source may be an annulas surrounding the nozzle and having its inwardly and downwardly facing surfaces of perforated metal sheet and the outermost surfaces may be disposable in order to tolerate metal splashing. The need for a tube to enclose the protective gas is avoided.