Effect of point defects on mechanical properties of metals. Technical progress report

The major research effort was on iron. The recovery of the electron irradiation effect was studied in pure iron and iron-carbon alloys. This investigation resulted in several new findings in addition to the confirmation of two assumptions used in the interpretation of the mechanical effects of electron irradiation on high-purity iron single crystals. The irradiation softening effect was studied in single crystals oriented for the (011) slip and polycrystalline specimens. Then, a striking orientation effect was discovered and a large irradiation softening was found in single crystal specimens oriented for the hard (121) slip. In this oriertation, more than 60% of the yield stress is reduced by electron irradiation; thereby, the hardest oriertation becomes the softest orientation following electron irradiation. The solution softening and hardening effects of carbon atoms were investigated using highpurity iron single crystills similar to those used in the irradiationsoftening study. The general behavior of the softening and hardening was in good agreement with a proposed theory based on the irradiation- softening experiments. (auth