Electron irradiation hardening of copper and copper alloys at 78 and 300 K

Electron irradiation hardening of Cu, CuNi, CuSi, and CuGe single crystals was measured at 78 and 300 K. From a comparison with the theory of Frank it is concluded that the hardening after 78 K irradiation is due to interstitial tetragonlity. After 300 K irradiation, an extraordinarily large hardening rate per point defect introduced is observed. Although the mechanism of this hardening is not understood in detail it is attributed to interstitial clusters. From these results it is concluded that interstitial atoms, which exist individually or as complex with solute atoms after 78 K irradiation, move and form clusters at higher temperatures. The temperature dependence of the yield stress after electron irradiation is measured and the effect of the irradiation on the anomaly below 100 K is observed.