Effect of Electron Irradiation on Young's Modulus

Young's modulus and internal friction measurements are reported on high‐purity copper following electron bombardment. The modulus is observed to rise rapidly with electron flux reaching an early saturation followed by a slow decrease. The rapid saturation is attributed to dislocation pinning. The rate of saturation is temperature dependent in the range from −195°C to about 0°C suggesting defect migration at low temperatures. The slow decrease is attributed to a ``bulk effect'' due to interstitial‐vacancy pairs.