Effect of the Small Punch Test sample geometry on the Liquid Metal Embrittlement of Cu-30 wt% Zn by the eGaIn

Abstract

Liquid metal embrittlement (LME) is the embrittlement or the modification of the fracture behaviour of a metal or alloy when it undergoes plastic deformation while in contact with a liquid metal or liquid alloy. LME occurrence depends strongly on the properties of the metals involved and on the conditions of the mechanical stresses applied to the solid. The Small Punch Test (SPT) on flat specimens is very sensitive to identify the conditions of LME occurrence. Moreover, there are alternative SPT notched specimen geometries that have the potential to screen solid/liquid couples for sensibility to LME in different conditions. To study the apparition of the LME on an alpha brass with 30 wt% Zn in contact with the eGaIn (Ga-In eutectic), SPT at room temperature were carried out at different displacement rates and using three specimen types: the standard flat geometry and two notched geometries. While the flat specimens did not present LME, the presence of a notch and a high strain rate induced LME on the other specimen geometries. For these last specimens, the eGaIn modifies the SPT load-displacement curves at the crack propagation stage and changes the fracture to a partially ductile fracture followed by a brittle fracture.