Effect of cooling rate on mechanical properties of aged ITER-grade CuCrZr

The effects of the cooling rate on the microstructure and the mechanical properties of aged CuCrZr alloys were examined. The CuCrZr alloys were solution annealed at 980 deg. C for 0.5 h, cooled down by four different cooling methods and then aged at 400-620 deg. C for 2 h. The strength showed the highest value at an aging temperature of 440 deg. C irrespective of the cooling rate and it was decreased gradually with an increase of the aging temperature up to 620 deg. C. The strength of the CuCrZr alloys was highly dependant on the distribution of the precipitates and the highest strength was obtained in the CuCrZr alloys with a number of Guinier-Preston zones. For the same aging temperature, the strength was increased with the cooling rate but the difference in the strength became smaller when the CuCrZr alloys were aged at above 580 deg. C. The yield strength of the CuCrZr alloys was higher than the minimum value (150 MPa at 250 deg. C) required for the design of the International Thermonuclear Experimental Reactor first wall up to an aging temperature of 600 deg. C when a gas cooling method after a solution annealing was performed with cooling rates of 89 and 207 deg. C/min