Composition screening of Zr-Cu-Al-Y bulk metallic glasses

https://doi.org/10.1016/j.jnoncrysol.2019.119879Get rights and content

Highlights

  • A new composition design method for bulk metallic glasses was proposed.

  • The glass-forming ability relates to the types of competing crystalline phases.

  • There is a threshold driving force for glass formers.

  • The glass formation ranges of the Zr-Cu-Al-Y system (xy = 2, 5 at.%) were determined.

  • The amorphous rod of 8 mm in diameter was obtained in the Zr50Cu30Al15Y5 alloy.

Abstract

A new composition design method that combines the deep-eutectic rule and the driving-force criterion has been proposed and applied to the typical Zr-Cu-Al-Y bulk metallic glass system. By thermodynamic calculation and experimentation, the glass formation ranges at 2 at.% and 5 at.% Y were determined, and an amorphous rod of 8 mm in diameter was obtained in the Zr50Cu30Al15Y5 alloy with the aid of parameter criterions additionally. The results indicate that the glass-forming ability relates to the types of the competing crystalline phases during the glass formation. Unlike binary or ternary compounds, having the solid solution phase as the competing phase would deteriorate the glass-forming ability. Moreover, the driving-force is a necessary condition for the glass formation and has a threshold value for the glass formers. The findings in this work would provide an important guidance for the reliable and efficient composition design of novel bulk metallic glasses.

Introduction

With the development of the metallic glasses for decades, numerous criteria and methods have been put forward to predict the glass-forming ability. Generally, they can be classified into two categories. One of them involves various parameter criterions, such as △Tx (= Tx - Tg), Trg (= Tg/Tl), γ (= Tx/(Tg + Tl)) and γm (=(2Tx - Tg)/Tl) etc. [1], [2], [3], [4], which are only related with the characteristic temperatures. The other is related with the thermodynamic properties, kinetic property and the electronic (or atomic) structure. Thermodynamic properties like mixing enthalpy, mismatch entropy, formation enthalpy of competing phases and precipitation driving force of the crystalline phases in the supercooled liquid are often calculated to predict the glass-forming ability [5], [6], [7], [8], [9], [10], [11], [12]. Kinetic property like the melt viscosity is considered as the main factor that dominates the glass-forming ability of Zr-based bulk metallic glasses [13]. There are also electron concentration, average atomic size and cluster line criteria, and the molecular dynamics method, which are related with the electronic or atomic structure [14], [15], [16], [17]. Other researchers predict the glass-forming ability combining the thermodynamics and kinetics [18], [19], [20], [21]. For instance, Wang et al. [20] constructed a combining function considering both thermodynamic and kinetic factors, i.e. fusion entropy, fragility, glass-transition temperature and the liquidus temperature. However, it is hard for the above criteria or methods to be universally applicable. It has always been a challenge that researchers are even facing nowadays to accelerate the composition design of a multi-component bulk metallic glass from numerous combinations of so many elements in the periodic table.

Admittedly, the CALPHAD method has demonstrated its power in the design and development of novel multi-component materials, from the traditional alloys to the bulk metallic glasses and the rising high-entropy alloys [22], [23], [24], [25], [26], [27], [28]. Glass formation is a very complicated process, which is controlled by both the thermodynamic factor, i.e. the driving force of the crystalline phases, and the kinetic factor, i.e. the viscosity of the supercooled liquid. Then, how well can one design the bulk metallic glasses only from the thermodynamic point of view? In this work, the deep-eutectic rule and the driving force criterion are combined to explore the glass-forming ability of the Zr-Cu-Al-Y typical bulk metallic glass system based on the CALPHAD method in order to unveil this answer and give the insight into the correlation between thermodynamics and glass-forming ability.

Section snippets

Methods on design and experiments

The thermodynamic description of the Zr-Cu-Al-Y quaternary system is established by extrapolating the thermodynamic descriptions of the constituent ternary systems within the framework of the CALPHAD method. For the four ternary sub-systems, the thermodynamic parameters of the Zr-Cu-Al and Al-Cu-Y are adopted from the literatures [25,29], while those of the other two ternary systems are extrapolated from the constituent binary systems since there is no ternary compound and no homogeneity range

On the first round of preliminary design

Using the established thermodynamic database of the Zr-Cu-Al-Y quaternary system, a total of 105 invariant reactions are obtained by calculation. Of all the eutectic reactions listed in Table 1, four are considered to be valuable to the composition design of bulk metallic glasses, i.e. E8, E11, E12 and E13. They are predicted to happen at relatively low temperatures and the eutectic points are not too close to one corner. The four eutectic alloys, named 1E#−4E# as given in the table, were first

Discussion

From the glass-forming ability sequence of 1E#>2E#>3E#/4E# and 2E′#<3E′# as well as the predicted crystalline phases by solidification simulation, it can be seen that the glass-forming ability is related with the types of the competing crystalline phases. It is not favorable for the glass formation with the solution phase as one of the competing phases, and even worse when there are two, since the atoms arrange disorderly in the solution phase and it is easy to be formed. By contrast, it is

Conclusions

Combining the CALPHAD method with key experiments and parameter criterions, the glass-forming ability of the Zr-Cu-Al-Y system at 2 at.% and 5 at.% Y has been investigated. An amorphous rod of 8 mm in diameter has finally been obtained in the Zr50Cu30Al15Y5 alloy, second only to the classic Zr42Cu46Al7Y5 alloy. It has been found that the glass-forming ability of the alloys is not inversely proportional to the temperature of the deep eutectic reaction. It turns out to be related to the types of

CRediT authorship contribution statement

H. Bo: Conceptualization, Methodology, Validation, Writing - original draft, Writing - review & editing. Y.P. Du: Data curation, Investigation. J.L. Hu: Validation, Writing - review & editing. D.D. Lu: Data curation, Investigation. L.M. Wang: Validation, Writing - review & editing.

Declaration of Competing Interest

I declare that we have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This work was financially supported by National Natural Science Foundation of China (Grant No. 51401179), National Key R&D Program of China (Grant No. 2018YFA0703602), National Basic Research Program of China (973 Program No. 2015CB856805), Natural Science Foundation of Hebei Province (Grant No. E2015203116) and Top Young Talents Project of the Education Department of Hebei Province (Grant No. BJ2019001).

References (33)

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