High-Accuracy X-Ray Diffraction Analysis of Phase Evolution Sequence During Devitrification of Cu^sub 50^Zr^sub 50^ Metallic Glass

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Physical metallurgy and materials science, 2011-05, Vol.42 (5), p.1144
• Main Authors: Kalay, I, Kramer, M J, Napolitano, R E
• Format: Article
• Language: English
• ISSN: 1073-5623; 1543-1940

Real-time high-energy X-ray diffraction (HEXRD) was used to investigate the crystallization kinetics and phase selection sequence for constant-heating-rate devitrification of fully amorphous Cu^sub 50^Zr^sub 50^, using heating rates from 10 K/min to 60 K/min (10 °C/min to 60 °C/min). In situ HEXRD patterns were obtained by the constant-rate heating of melt-spun ribbons under synchrotron radiation. High-accuracy phase identification and quantitative assessment of phase fraction evolution though the duration of the observed transformations were performed using a Rietveld refinement method. Results for 10 K/min (10 °C/min) heating show the apparent simultaneous formation of three phases, orthorhombic Cu^sub 10^Zr^sub 7^, tetragonal CuZr^sub 2^ (C11^sub b^), and cubic CuZr (B2), at 706 K (433 °C), followed immediately by the dissolution of the CuZr (B2) phase upon continued heating to 789 K (516 °C). Continued heating results in reprecipitation of the CuZr (B2) phase at 1002 K (729 °C), with the material transforming completely to CuZr (B2) by 1045 K (772 °C). The Cu^sub 5^Zr^sub 8^ phase, previously reported to be a devitrification product in C^sub 50^Zr^sub 50^, was not observed in the present study. [PUBLICATION ABSTRACT]