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

Marco Ezequiel,Ingrid Proriol Serre

doi:10.1051/matecconf/202134902014

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.

Highlights

A solid metal or alloy that undergoes plastic deformation while in contact with a liquid metal or a liquid alloy may present liquid metal embrittlement (LME)
There was an effect of the eGaIn on the fracture behaviour of the brass Cu30 wt% Zn when using the notched specimens, but not when using the standard specimens. These results indicate that both notched geometries are more suitable to study the LME phenomenon than the standard flat geometries
Using the Small Punch Test (SPT) with standard specimen geometries did not show any effect of the eGaIn on the mechanical properties of the 30 wt% Zn brass at any of the displacement rates tested

Summary

Introduction

A solid metal or alloy that undergoes plastic deformation while in contact with a liquid metal or a liquid alloy may present liquid metal embrittlement (LME) This phenomenon induces a change in the fracture behaviour of the solid and a decrease in its mechanical properties [13]. There are alternative notched specimen geometries designed by [7] and [8] to measure the fracture toughness through the SPT in non-corrosive environments These alternative notched geometries, not yet used for LME sensitivity studies, could be more suitable to study the sensibility of a solid/liquid couple to LME than the standard flat geometries. On the couples Cu-30 wt% Zn/Ga [5] and T91/Pb [9, 10] LME was not present on unnotched tensile specimens; on notched tensile specimens, there was a clear apparition of LME

Methods

Results

Conclusion