FACTORS AFFECTING Y2BACUO5 PRECIPITATE SIZE DURING MELT PROCESSING OFYBA2CU3O7-X

In the microstructures of melt processed YBa2Cu3O7-x (123) superconduc tors, often unconsumed Y2BaCuO5 (211) particles are observed. The 211 particle size and distribution depend upon i) processing parameters su ch as peak temperature, heating rate, residence time above 1010 degree s C, starting 123 grain size, etc., ii) second phase additions, and ii i) the processing route employed. 211 particle size control is of prim ary interest for enhancing 123 flux pinning, and fracture toughness. F actors which determine the 211 particle size are reviewed.