Method and an apparatus for manufacturing metallic composite material bars by unidirectional solidification

A method of producing an alloy bar by unidirectional solidification comprising the steps of:

• (a) positioning a heat source above a cold source in a melting and solidification zone;
• (b) continuously displacing an elongated tubular mold having a cross sectional shape corresponding to that of the bar to be produced through said heat source and said cold source downwardly at a constant rate over the length of said mold to form a molten liquid portion of alloy in said mold and enable solidification of molten alloy within said mold below said liquid portion;
• (c) setting the relative efficiency of said sources and the displacement speed of said mold to maintain a planar solidification front at the bottom of said liquid portion with a high thermal gradient at the level of said front with said mold being progressively lowered past said front and a solidified bar being formed at said front with continuous and progressive increase in length as said mold is lowered past said front,
• (d) sensing the position of said solidification front;
• (e) controlling the relative efficiency of said sources in response to the sensing of said front to maintain constant the temperature in the area of said front;
• and
• (f) continuously feeding a powder of said alloy at a substantially constant rate into said mold to maintain said liquid portion with a small but substantially constant volume over the entire duration of solidification of said bar and for the entire length of formation thereof, the feed rate of said alloy powder being controlled to correspond to the rate of alloy solidification at said front so that said bar has substantially constant mechanical and structural properties over its entire length.