First Principles Study of Adsorption of Hydrogen on Typical Alloying Elements and Inclusions in Molten 2219 Al Alloy.

Yu Liu,Zhengbing Xiao,Yuanchun Huang,Guangze Jia

doi:10.3390/ma10070816

Abstract

To better understand the effect of the components of molten 2219 Al alloy on the hydrogen content dissolved in it, the H adsorption on various positions of alloying element clusters of Cu, Mn and Al, as well as the inclusion of Al2O3, MgO and Al4C3, were investigated by means of first principles calculation, and the thermodynamic stability of H adsorbed on each possible site was also studied on the basis of formation energy. Results show that the interaction between Al, MgO, Al4C3 and H atoms is mainly repulsive and energetically unfavorable; a favorable interaction between Cu, Mn, Al2O3 and H atoms was determined, with H being more likely to be adsorbed on the top of the third atomic layer of Cu(111), the second atomic layer of Mn(111), and the O atom in the third atomic layer of Al2O3, compared with other sites. It was found that alloying elements Cu and Mn and including Al2O3 may increase the hydrogen adsorption in the molten 2219 Al alloy with Al2O3 being the most sensitive component in this regard.

Highlights

It is well known that the presentation of gases in molten aluminum can cause metallurgy defects [1], such as porosity, in castings, which could raise stress and cause pre-failure in the process of manufacturing and using a product [2]
To remove hydrogen from molten aluminum, the behavior of hydrogen in molten aluminum, which is highly associated with the interaction between hydrogen and the components of molten aluminum, must firstly be understood [9,12], since it plays an important role in the process of removing hydrogen, especially for high-efficiency degassing
Where EH/slab and Eslab are the total energies of the slab with and without H adsorption, respectively, and EH2 is the total energy of a H2 molecule

Summary

Introduction

It is well known that the presentation of gases in molten aluminum can cause metallurgy defects [1], such as porosity, in castings, which could raise stress and cause pre-failure in the process of manufacturing and using a product [2]. Hydrogen is the main gas that is dissolved in molten aluminum [3]; when the hydrogen content reaches a critical value in front of metallic solidifying interface, molecular hydrogen bubbles form and may grow, depending on the local hydrogen concentration levels [4]. The removal of the hydrogen from the molten aluminum prior to casting is crucial for the production of high-quality castings, since it plays a key role in determining the performance of the final products. To remove hydrogen from molten aluminum, the behavior of hydrogen in molten aluminum, which is highly associated with the interaction between hydrogen and the components of molten aluminum, must firstly be understood [9,12], since it plays an important role in the process of removing hydrogen, especially for high-efficiency degassing. With Hyscan-II hydrogen testing equipment, they found that both Mg and Si

Methods

Results

Conclusion