Orientation of Nickel-Based Alloy after Thermal Treatment

The paper presents transmission electron microscopy investigations of Ni-Al-Co alloy with gamma'-and gamma -phases obtained by directional crystallization. The main alloying elements are Cr, Ta, and Re in the amount of no more than 3.5.t % each. W and Mo are present in a smaller amount. The alloy structure is investigated in two states: (1) original (after directional crystallization and long-term homogenezation which includes a series of annealing ranging from 1285 to 1340 degrees C) and (2) original state subjected to subsequent annealing within 900-1000 degrees C temperature range during 105-1143 h. The experiments show that the annealing process causes the fracture of the ideal quasi-cuboid structure of the gamma'-phase and modifies its preferable orientation. The increase in the annealing temperature modifies the morphology of the gamma'-phase that, in turn, changes the grain orientation in the alloy.