Effect of post-irradiation heat treatment on mechanical properties of OFHC-copper and copper alloys

The present report describes the results of post-irradiation annealing experiments carried out to test the possibility as to whether or not such treatments can be used to improve the ductility of copper alloys irradiated and tested at temperatures below the recovery stage V. Tensile specimens of OFHC-copper, CuCrZr, CuNiBe, CuAl-25 and CuAl-60 were irradiated with fission neutrons in the DR-3 reactor at Risø at 100 deg.

C to different displacement dose levels. Some of the specimens were tested in the as-irradiated conditions whereas others were given a post-irradiation heat treatment (PIHT) at 300 deg. C for 50 h and then tested at 100 deg. C. The results show that PIHT leads to only a partial recovery and that the level of recovery depends on the irradiation dose level.

It is important to note, however, that the PIHT does eliminate the problem of yield drop and plastic instability and does reinstate enough of the uniform elongation to render the material useful again. It is suggested that more systematic investigations are necessary to determine whether or not this advantage can be maintained if the materials were to experience such cycles of irradiation and annealing repeatedly. (au).