Intermetallic Growth and Interfacial Properties of the Grain Refiners in Al Alloys.

Chunmei Li,Nanpu Cheng,Zhongjing Xie,Liangliang Hui,Zhiqian Chen

doi:10.3390/ma11040636

Abstract

Al3TM(TM = Ti, Zr, Hf, Sc) particles acting as effective grain refiners for Al alloys have been receiving extensive attention these days. In order to judge their nucleation behaviors, first-principles calculations are used to investigate their intermetallic and interfacial properties. Based on energy analysis, Al3Zr and Al3Sc are more suitable for use as grain refiners than the other two intermetallic compounds. Interfacial properties show that Al/Al3TM(TM = Ti, Zr, Hf, Sc) interfaces in I-ter interfacial mode exhibit better interface wetting effects due to larger Griffith rupture work and a smaller interface energy. Among these, Al/Al3Sc achieves the lowest interfacial energy, which shows that Sc atoms should get priority for occupying interfacial sites. Additionally, Sc-doped Al/Al3(Zr, Sc) interfacial properties show that Sc can effectively improve the Al/Al3(Zr, Sc) binding strength with the Al matrix. By combining the characteristics of interfaces with the properties of intermetallics, the core-shell structure with Al3Zr-core or Al3Zr(Sc1-1)-core encircled with an Sc-rich shell forms.

Highlights

Experimental studies [1,2] have repeatedly shown that Al3 Ti and Al3 Zr particles act as the heterogeneous nuclei and dramatically refine the grains of the α-Al3 Zr(Sc2-1) (Al) matrix
Recent investigations indicate that Al3 Sc and Al3 (Zr, Sc) are perfect substitutions as grain refiners for Al-Zn-Mg alloys [3,4,5]
Al3 TM(TM = Ti, Zr, Hf, Sc) and Al3 (Zr, Sc) phases combined with the interfaces of the Al been investigated by using the first-principles method on the basis of the DFT

Summary

Introduction

Experimental studies [1,2] have repeatedly shown that Al3 Ti and Al3 Zr particles act as the heterogeneous nuclei and dramatically refine the grains of the α-Al matrix. Al3 (Sc1-x Zrx ) nano-particles that can ensure a good stability of the fine-grained structure during superplastic deformation. In the Al-5.70Zn-1.98Mg-0.35Cu-0.25Sc-0.10Zr alloy [4], Al3 (Sc1-x Zrx ) nano-particles play an important role in accelerating the cooperative grain boundary deformation and affect the dynamic softening deformation mechanism of Al-Zn-Mg alloys. The Sc and Zr additions to the Al-Cu-Mg alloy [5] could strongly inhibit recrystallization, refine grain size, impede the segregation of the Cu element along the grain boundary, and increase the spacing of grain boundary precipitates. All these experimental results confirm the importance of refiners

Methods

Results

Conclusion