Microstructure and Strengthening Mechanism of ITER-Grade CuCrZr alloy after High Energy Shot Peening

Microstructure and hardening effects of Cu-0.8Cr-0.1Zr alloy by high energy shot peening (HESP) were researched by X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and microhardness tester. On the base of experiment results, the strengthening mechanism of HESPed alloy was discussed. The results show that there are two kinds of deformed zone with different deformation levels, called severe deformation layer and deformation layer, respectively, within about 300 Am depth from the surface of HESPed samples. The higher dislocation density as well as twins and dislocation cells were observed within the severe deformation layer. With increasing in HESP time, the grain size in severe deformation of alloy is refined to about 80 nm and the hardness is up to 1.99 GPa, which is twice as that of undeformed alloy. The strengthening mechanism belongs to work hardening and grain refinement strengthening; however, the contribution to strength by work hardening is more significant than that by grain refinement.