Influence of Elasticity of Dislocations on Thermal Motion of Trapped Liquid Pb Inclusions in Al

Abstract

Thermal motion of nanoscale liquid Pb inclusions attached to fixed dislocations in thin Al foils is investigated using in-situ TEM. In contrast with 3D random motion of free inclusions, the attached inclusions demonstrate oscillations in the close proximity of the dislocations. This is due to the elasticity of the dislocations. It is found that inclusions captured by one dislocation repulse at small separations, and attract at large ones and this is also caused by the dislocation elasticity. Such behaviour of trapped inclusions can be considered as a motion in a potential well or in coupled potential wells in the case of motion of several trapped inclusions on one dislocation. The potential of interaction of an inclusion with a dislocation and the potential of mutual interaction between inclusions are determined.

Correlated thermal motion of two liquid Pb inclusions attached to a fixed dislocation in an Al matrix

“…Earlier, we had reported the study of thermal motion of two nano-sized liquid Pb inclusions attached to a fixed dislocation in an Al matrix at 447°C using in situ TEM, where the indication was found the inclusions interacted with each other [6]. In our later paper [8] the shape of the potential of the interaction of these inclusions was evaluated using the experimental data obtained in [6]. The present paper considers comprehensively thermal motion of the same two inclusions attached to the dislocation.…”

“…The powers of 2 and −2, respectively, in the empirical potential were found from a log-log plot of the coordinates giving straight lines with slopes of 2 and −2 of the potential far from the minimum [8]. Then, the analytical shape (…”

“…Whilst free inclusions in the matrix can exhibit 'traditional' 3D random walk [1][2][3], one or several inclusions attached to a fixed dislocation exhibit oscillations around the dislocations line [3][4][5][6][7]. This behavior can be explained by elastic interactions between the inclusions and the dislocation [3,5,8]. From thermal motion data obtained in in situ TEM experiments the diffusion coefficients of He bubbles [9] and liquid Pb inclusions [3][4][5]10] attached to fixed dislocations in Al-based alloys were determined.…”