Directional Recrystallization Processing of Additively Manufactured Ni-Base Superalloys to Achieve Columnar or Single-Crystal Grain Structures

A method and apparatus used in preparing a recrystallized metal alloy involve a cooling medium and a heating element to create a cold zone and a hot zone. An additively manufactured metal alloy preform is drawn in a draw direction from the cold zone towards the hot zone to form the recrystallized metal alloy. The cold zone and the hot zone create a surface temperature gradient on at least a portion of the preform of at least about 104 K m−1. The step of drawing causes an average grain size of at least a portion of the preform to increase in a direction parallel to the draw direction.