THE FORMATION OF HELIUM BUBBLES IN 316L SS IRRADIATED WITH HELIUM-IONS AT DIFFERENT TEMPERATURES

Specimens of 20% cold worked 316L SS were irradiated with 2.5 MeV He-4 (+) at room temperature, 500 and 600 degrees C separately. The bubble structures in bulk were investigated in a transmission electron micros cope with cross sectional technique. As the irradiation temperature is raised from room temperature to 500 degrees C, the bubbles grow slowl y. When the irradiated temperature is varied from 500 to 600 degrees C , the bubbles grow very fast. This means there is a turning point of b ubbles evolution between 500 and 600 degrees C. At the same temperatur e, the bubble size and density tend to saturation with the increasing of helium atom concentration and displacement per atom (dpa).