Relationship Between the Thermodynamic Parameters, Structure, and Anticorrosion Properties of Al-Zr-Ni-Fe-Y Alloys

R Babilas,A Bajorek,W Łoński,A Radoń,K Młynarek

doi:10.1007/s11661-020-05833-x

Abstract

The influence of the chemical composition on the crystallization process, amorphous phase formation, and the anticorrosion properties of Al-Zr-Ni-Fe-Y alloys are presented. To reduce the number of experiments, a thermodynamic approach was applied in which the entropy and Gibbs free energy of representative alloys were optimized. The low glass-forming ability of Al-Zr-Ni-Fe-Y alloy systems was related to the crystallization of the Al3Zr phase from the melt. The structural analysis showed that phases containing Ni and Fe, such as Al19Ni5Y3, Al10Fe2Y, and Al23Ni6Y4, played a key role in the formation of amorphous alloys. According to this, the simultaneous addition of Ni/Fe and Y is important to prevent the crystallization of Al-based alloys in the melt. The formation of an amorphous phase in Al80Zr5Ni5Fe5Y5 alloys and the complete amorphization of Al85Ni5Fe5Y5 alloys were responsible for the high corrosion resistance compared with fully crystalline alloys. Moreover, the addition of Y had a significant impact on the anticorrosion properties. The XPS results showed that the alloys tended to form a passive Al2O3 and Y2O3 layer on the surface.

Highlights

LIGHTWEIGHT alloys are mainly applied in the aerospace industry where high strength and low density are required
This analysis showed that the light gray grains in the form of short plates were associated with the presence of the Al3Y phase, whereas the dark gray grains in the form of long, well-crystallized plates were Al3Zr phase
The brown grains were related to phases containing Al with Fe or/and Ni and the observed shades are related to the concentration of these elements in the phases

Summary

Introduction

LIGHTWEIGHT alloys are mainly applied in the aerospace industry where high strength and low density are required. The application of conventional aluminum alloys is limited due to their relatively low strength, which is insufficient for advanced structural applications.[1]. Particular attention has been paid to aluminum alloys whose structure and properties can be improved by rapid solidification (RS). Al matrix alloys produced by RS are characterized by their non-equilibrium phases: amorphous single phase, partially crystallized particles in an amorphous matrix, quasicrystalline structures consisting of quasicrystals in an Al matrix without a grain boundary, and granular amorphous phases of aluminum with or without a surrounding amorphous phase.[1,2] Bulk metallic glasses (BMGs) are an interesting group of materials produced by RS, and Al-based BMGs (Al-BMGs) are a promising group of Manuscript submitted November 26, 2019.

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