Positron annihilation lifetime spectroscopy of annealed tungsten

Three samples of 99.97% pure rolled tungsten were annealed at 700 degrees C, 1000 degrees C, and 1400 degrees C in a vacuum of about 10(-6) mbar for 1 h. Then the effects of annealing were investigated. For this purpose, defects and their structure in the three annealed samples and the as-received sample, were studied, characterized, and compared by the positron annihilation lifetime spectroscopy (PALS) technique. A large number of mono-vacancy and cavity defects were determined in the as-received sample. The results show that by increasing the temperature, the density, and size of the defects drastically decreased, and their structure changed to dislocation/vacancy loops. The structure and status of defects in annealed samples are almost constant. tau(ave) with a 40% decrease in 1400 degrees C compared to as-received, indicates the beginning of removing defects from tungsten at the temperature of 1400 degrees C.

Automated summary

Three samples of 99.97% pure rolled tungsten were annealed at different temperatures, and the effects of annealing on defects and their structure were investigated. The results showed that increasing the annealing temperature can significantly decrease the density and size of defects and change their structure. Defect removal from tungsten begins at a temperature of 1400 degrees C.