Effect of Multiple Alloying Elements on the Glass-Forming Ability, Thermal Stability, and Crystallization Behavior of Zr
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METALLIC glasses are non-crystalline materials with a disordered arrangement of the constituent atoms. They possess an interesting combination of high strength, good corrosion resistance, and useful magnetic properties. Metallic glasses (or amorphous solids) were first synthesized in thin-film form by vapor deposition[1,2] and later by rapid solidification from the liquid state at high rates of about 105 to 106 K/s.[3,4] Subsequently, bulk metallic glasses (BMGs), in large section sizes, were obtained by slow cooling from the liquid state, as in a casting process.[5] BMGs also show a good combination of physical,[5] mechanical,[6–9] magnetic,[10,11] and chemical[12] properties and exhibit high strength, hardness, wear resistance, and large elastic deformation.[13] The largest diameter of the glassy rod with a diameter of 80 mm has been produced in a Pd-based alloy.[14]
A.I. BAZLOV and A.A. TSARKOV are with the National University of Science and Technology MISiS, Moscow, Russia, 119049. Contact e-mail: [email protected]. S.V. KETOV is with the Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, 8700 Leoben, Austria. C. SURYANARAYANA is with the Department of Mechanical and Aerospace Engineering, University of Central Florida, Orlando, FL 32816-2450. D.V. LOUZGUINELUZGIN is with the WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan. Manuscript submitted September 8, 2017.
METALLURGICAL AND MATERIALS TRANSACTIONS A
The glass-forming ability (GFA) of an alloy is an important parameter that helps in identifying appropriate compositions to achieve glass formation in a wide composition range and also in larger diameters. Several criteria have been proposed to estimate and/or establish GFA of alloys and these are based on either thermodynamic parameters, glass transformation temperatures, or modeling studies. There have been successes with some parameters in some alloy systems and it has been shown that not all the criteria proposed satisfactorily explain the GFA of all alloy systems.[15] Table I lists the different criteria that have been proposed and commonly used in evaluating the GFA of alloys.[16–28] The GFA of an alloy is determined not only by the composition of the base alloy, purity of the constituent elements, and the atmosphere in which it is cast, but also by the nature of the alloying additions made.[29–31] The atomic size difference between the base metal and the alloying element, their chemical interactions, and thermodynamic properties determine the effectiveness of the alloying element in enhancing the GFA of the alloy system. Zr-based metallic glasses have been investigated for a long time[32] owing to their good GFA and also their mechanical properties.[33] Starting from thin ribbons obtained by rapid solidification processing,[34] Zr-based alloys have been cast as bulk metallic glasses by slow solidification processes up to about 30 mm in diameter,[35] and currently the maximum diameter reported for a Zr-based glassy alloy is 73 mm.[36] A bi
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