The recrystallization temperature of lanthanum-doped molybdenum wire is higher than pure molybdenum wire, and it is because small amount of La2O3 can improve the properties and structure of molybdenum wire. Besides, La2O3 second phase effect can also increase the room temperature strength of the molybdenum wire and improve the room temperature brittleness after recrystallization.
Recrystallization Temperature Comparison: The microstructure of pure molybdenum wire was obviously broadened at 900 ℃ and recrystallized at 1000 ℃. With the annealing temperature increase, recrystallization grains also increase, and fibrous tissues significantly reduce. When the annealing temperature reaches 1200 ℃, molybdenum wire has been completely recrystallized, and its microstructure shows a relatively uniform equiaxed recrystallized grains. As the temperature increases, the grain grows unevenly and appears coarse grains. When annealed at 1500 ℃, the molybdenum wire is easy to break, and its structure shows coarse equiaxed grain. The fiber structure of lanthanum-doped molybdenum wire broadened after annealed at 1300 ℃, and the tooth-like shape appeared at the boundary of the fiber. At 1400 ℃, the recrystallized grains appeared. At 1500 ℃, the fiber texture decreased sharply, and the recrystallized structure appeared obviously, and the grains grew unevenly. The recrystallization temperature of lanthanum-doped molybdenum wire is higher than that of pure molybdenum wire, which is mainly due to the effect of La2O3 second phase particles. The La2O3 second phase hinders the grain boundary migration and grain growth, thus increasing the recrystallization temperature.
Room Temperature Mechanical Properties Comparison: The elongation of pure molybdenum wire increases with annealing temperature increasing. When the anneal temperature at 1200 ℃, the elongation reaches the maximum value. The elongation decreases with the anneal temperature increasing. Annealed at 1500 ℃, and its elongation is almost equal to zero. The elongation of La-doped molybdenum wire is similar to pure molybdenum wire, and the elongation rate reaches the maximum when annealed at 1200 ℃. And then the elongation decreases with temperature increasing. The only different is the reduction rate is slow. Although the elongation of lanthanum-doped molybdenum wire is slowed down after annealing at 1200 ℃, the elongation is higher than pure molybdenum wire.