Chemisorption-facilitating dislocation emission, multiplication and motion

Abstract

The reduction in ductility and fracture stress of many metals tested in certain liquid metal environments is generally known as liquid metal embrittlement (LME). The evidence for plastic deformation on the fracture surfaces of LME failures has led Lynch to propose that the chemisorption of liquid metal can enhance localized plastic deformation. Up to now, however, direct proof of chemisorption facilitating dislocation emission, multiplication and motion is lacking. The purpose of this paper is to study now chemisorption facilitates dislocation emission, multiplication and motion. An in-situ tensile test in a TEM is the most direct and powerful method for studying the dislocation emission, multiplication and motion. Since there is no way to put the liquid metal into a TEM, a special constant deflection loading device has been designed. Using this device, the effect of chemisorption on dislocation emission and motion can be studied based on the dislocation configuration change ahead of a loaded crack tip after chemisorption of liquid metal atoms but before the propagation of the original crack tip or initiation of a new microcrack.