BIAS OF BASAL DISLOCATION LOOP IN ZIRCONIUM

An analytical expression for the elastic interaction energy of radiation point defects of the dipole type with the basal dislocation loop of the hcp metal is obtained using the Green's function method for hexagonal crystals in the Krener approach. It was used for numerical calculation of the bias for the basal dislocation loop of zirconium in a toroidal reservoir. The toroidal geometry of the reservoir allows one to perform the calculation for a loop of any size and without any correction of the elastic field in its region of influence. The dependencies of the loop bias on its radius and nature are obtained for various shapes of dipole defects.

Two-dimensional vacancy platelets as precursors for basal dislocation loops in hexagonal zirconium

Zirconium alloys are widely used structural materials of choice in the nuclear industry due to their exceptional radiation and corrosion resistance. However long-time exposure to irradiation eventually results in undesirable shape changes, irradiation growth, that limit the service life of the component. Crystal defects called <c> loops, routinely seen no smaller than 13 nm in diameter, are the source of the problem. How they form remains a matter of debate. Here, using transmission electron microscopy, we reveal the existence of a novel defect, nanoscale triangle-shaped vacancy plates. Energy considerations suggest that the collapse of the atomically thick triangle-shaped vacancy platelets can directly produce <c> dislocation loops. This mechanism agrees with experiment and implies a characteristic incubation period for the formation of <c> dislocation loops in zirconium alloys.

Revealing the Subsurface Basal 〈a〉 Dislocation Activity in Magnesium Through Lattice Rotation Analysis

A method was proposed in this study to reveal the subsurface basal dislocation activity in Mg-Y alloy and determine the corresponding Burgers vector. This is achieved by correlating the slip directions of dislocations to the lattice rotation represented by the {0001} pole figure. The identified basal slip system by this approach was verified by micro-Laue diffraction. This method can be applied as a complementary method to the conventional slip trace analysis to study the dislocation behavior of Mg alloys.