Atomistic Design of Favored Compositions for Synthesizing the Al-Ni-Y Metallic Glasses.

Q Wang,J B Liu,J H Li,B X Liu

doi:10.1038/srep16218

Abstract

For a ternary alloy system promising for obtaining the so-called bulk metallic glasses (BMGs), the first priority issue is to predict the favored compositions, which could then serve as guidance for the appropriate alloy design. Taking the Al-Ni-Y system as an example, here we show an atomistic approach, which is developed based on a recently constructed and proven realistic interatomic potential of the system. Applying the Al-Ni-Y potential, series simulations not only clarify the glass formation mechanism, but also predict in the composition triangle, a hexagonal region, in which a disordered state, i.e., the glassy phase, is favored energetically. The predicted region is defined as glass formation region (GFR) for the ternary alloy system. Moreover, the approach is able to calculate an amorphization driving force (ADF) for each possible glassy alloy located within the GFR. The calculations predict an optimized sub-region nearby a stoichiometry of Al80Ni5Y15, implying that the Al-Ni-Y metallic glasses designed in the sub-region could be the most stable. Interestingly, the atomistic predictions are supported by experimental results observed in the Al-Ni-Y system. In addition, structural origin underlying the stability of the Al-Ni-Y metallic glasses is also discussed in terms of a hybrid packing mode in the medium-range scale.

Highlights

Bulk metallic glasses (BMGs) have attracted considerable interest due to their fundamental scientific significance as well as great potential for engineering applications[1]
We propose to take a newly constructed Al-Ni-Y interatomic potential as the starting base together with a relevant simulation route to develop an atomistic approach which is capable of clarifying the formation mechanism, and predicting a favored glass formation region in its composition triangle and an amorphization driving force for each possible glassy alloy located inside the predicted GFR
To develop an atomistic approach, the construction of a realistic interatomic potential of an alloy system is of critical importance[25]

Summary

Introduction

Bulk metallic glasses (BMGs) have attracted considerable interest due to their fundamental scientific significance as well as great potential for engineering applications[1] To best utilize this class of materials, naturally, in the field of BMGs, the first priority issue is to clarify the formation mechanism, which could serve as guidance in synthesizing the desired glassy alloys[2,3,4,5]. The predicted GFR indicates the energetically favored alloy compositions, which could serve as guidance for the composition design in synthesizing BMGs. The predicted ADF, related to the energy difference between the glassy phase and the crystalline solid solution counterpart, could give hint to the readiness of metallic glass formation for a specific glassy alloy located in the GFR, and may somehow be correlated with the technical defined GFA by either obtainable size or applied cooling speed[6]. Besides the discussion of the prediction of GFR and ADF from the Al-Ni-Y potential, we will discuss how to apply the interatomic potential to characterize the atomic structure of the Al-Ni-Y metallic glasses via relevant computations and simulations[3,12,15]

Methods

Results

Conclusion