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La-TZM Alloy and TZM Alloy Microstructure After Annealing

Using powder metallurgy method to produce TZM alloy and doped lanthanum (La₂O₃) TZM alloy (La-TZM alloy). Comparing these two kinds of alloys at 1000 ℃, 1100 ℃, 1200 ℃, 1300 ℃, 1400 ℃, 1500 ℃ and 1600 ℃ microstructure after annealing understand the effect of La2O3 on alloy recrystallization temperature.
Two types of alloys anneal at 1000 ℃, 1100 ℃, 1200 ℃, 1300 ℃, 1400 ℃, 1500 ℃ and 1600 ℃ with hydrogen atmosphere protection and the annealing time is 1 hour. After annealing the alloys operate tensile test. Finally, using optical microscope to observe and to analyze the microstructure of the alloy obtain its recrystallization temperature.
TZM alloy annealing at 1100 ℃, its structure has clear direction, but it is not obvious elongated cold processing streamline structure and processing streamline at high temperatures gradually becomes widen. At 1200 ℃, the alloy streamline in the grain boundary extension, a large number of irregular grains appear. Influenced by cold working, the grain aspect ratio is reduced, but still directionality. Annealing at 1300 ℃, grain aspect ratio is further reduced, but there are still significant directivity. Compared with 1400 ℃ annealing, annealing at 1500 ℃, the grains grow significantly and directional weakened. After annealing at 1600 ℃, the grains grow significantly, complete recrystallization has occurred.
La-TZM alloy after 1100 ℃ annealing, it has fine grain, but it doesn’t show obvious streamline processing structure. At 1200 ℃ annealing, alloy exhibits streamline processing and a number of grain closely spaced. Annealing at 1300 ℃, grain boundary becomes wider and fine grains is increase, having clear direction. Annealing at 1400 ℃ grain boundaries become wider and shows a lot of elongated fine grains. Besides, there are obvious signs of cold working. After 1500 ℃ annealing, grain orientation is significantly and elongation, but there have been a number of large chunks of the grain. On the other hand, affected by cold working closely spaced grains becomes less. After annealing at 1600 ℃, the grain shows equiaxed and grain size is finer, direction completely eliminated.
 

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