In situ TEM research of dislocation emission and microcrack nucleation for Ti after adsorption by Hg

Abstract

Using a special constant deflection device, the change in dislocation configuration ahead of a loaded crack tip for a-Ti, before and after adsorption of Hg atoms, and the initiations of Hg-induced microcracks have been observed in TEM, as well as the in situ extension in TEM without Hg. The results showed that chemisorption of Hg atoms facilitates dislocation emission and motion. When the chemisorption-enhanced dislocation emission and motion develop into a critical situation, a microcrack in LME nucleates from the main crack tip and/or in the dislocation free zone (DFZ), and propagates in cleavage mode. During in situ extension in TEM without liquid metal, when dislocation emission and motion induced by thermal activity and applied stress reach a certain critical condition, microcracks nucleate but do not blunt into a void.