Neutron Irradiation Effects on Thermally Activated Process of Tensile Properties of Titanium

Radiation effects in nuclear reactor materials—correlation with structure

“…When irradiation hardening is purely athermal in nature, the flow stress vs temperature curve is just shifted up along the stress axis, resulting in curve C. Curve D represents the situation when irradiation increases both the components of flow stress. Most of the experimental results rule out situation B, consistent with the fact that most of the defects introduced by irradiation have both (Little 1976;Arsenault 1976) rcc and Intersection of Depleted zones (Diehl 1970) rlcP, c/a > ideal forest dislocations Faulted loops (Koppenal (basal slip) and Arsenault 1971) HCP c/a < ideal Interstitial Interstitial solutes (prism slip) solutes (Hamad et al 1975) P-N barrier Irradiation-induced defects (Kayano et al 1977) long range and short range interactions with dislocations and hence the athermal component of flow stress will invariably be increased by irradiation irrespective of whether the rate-controlling mechanism is altered (D) or not (C). A critical summary of the results indicating that the effects mainly depend on the crystal structure and the operative slip system is given in table 2 (Rodriguez 1977).…”

“…More recent work by Matta et al (1977) has confirmed these findings. Kayano et al (1977), on the other hand, found that in titanium, another .cP metal similar to zirconium in its deformation characteristics, the thermal activation parameters of deformation were altered by irradiation. Irradiation-produced defects, too small to be observed by electron microscopy, were considered to be related to the thermal component of stress.…”

“…Excellent reviews giving details of the results are available for FCC metals (Diem 1970; Koppenal and Arsenault 1971) and Bcc metals and alloys (Little 1976Arsenault 1976. Experimental studies on i~cP materials on the other hand have been very few (Hamad et al 1975 andKayano et al 1977). unirradiated yield stress also ceases at about room temperature, Little (1967) inferred that thermally-activated overcoming of radiation-produced defects occur only at temperatures above which the unirradiated rate-controlling mechanism becomes athermal; in the absence of the latter, the defects introduced by irradiation would have been rate-controlling even at lower temperatures.…”