Influence of the dislocation fastening by interstitials on the amplitude dependence of internal friction and some mechanical properties of molybdenum monocrystals

An investigation was performed to elucidate the effect of heat treatment on the amplitude dependence of internal friction and the mechanical properties of molybdenum monocrystals comprising various amounts of intrusion admixtures. Internal friction was measured at room temperature after tempering (from 1700 deg C in vacuum) and annealing (up to 720 deg C) in vacuo (10-5 mm mer. col.). A high damping level was observed after quenching. Annealing at temperatures exceeding 200 deg C caused lesser internal friction and resulted in its irrevocability, this being due to the formation of the so-called condensed atmosphere. This was accompanied by the main increase in hardening stress. Liberation of dislocations from atmospheres decreased cold brittleness temperature, while formation of segregations increased the said temperature. Hardening of dislocations by atmospheres improved molybdenum strength