Thermodynamic Investigation of Alkali-Metal-Induced High Temperature Embrittlement in Al-Li Alloys

Abstract

Alkali metals are undesirable impurity elements in aluminum-lithium alloys. Despite their trace amount, they lead to high temperature embrittlement (HTE). In the present work, the results of a thermodynamic investigation are presented to elucidate its mechanism and compared with available experimental data. HTE arises from an intergranular alkali-metal-rich liquid phase that segregates into grain boundaries from the matrix and significantly weakens their strength. A new model is developed to describe the tendency of HTE, which shows grain refinement can decrease the tendency.