Crystallization characteristics of the Mg-rich metallic glasses in the Ca–Mg–Zn system

• Published in: Journal of alloys and compounds Vol. 552; pp. 88 - 97
• Main Authors: Zhang, Y.N., Rocher, G.J., Briccoli, B., Kevorkov, D., Liu, X.B., Altounian, Z., Medraj, M.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 05.03.2013; Elsevier
• Subjects: Ca–Mg–Zn; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Crystallization; Differential scanning calorimetry; Electrical resistance; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Growth from solid phases (including multiphase diffusion and recrystallization); Materials science; Methods of crystal growth; physics of crystal growth; Mg-based biocompatible metallic glass; Physics; Solid-liquid transitions; Specific phase transitions; X-ray diffraction; X-ray diffraction; Electrical resistance; Differential scanning calorimetry; Ca–Mg–Zn; Crystallization; Mg-based biocompatible metallic glass; Electrical conductivity; Magnesium alloys; Composition effect; Melt spinning; XRD; Calcium alloys; Zinc alloys; Metallic glasses; Phase equilibria; Ca-Mg-Zn; Flow planar casting; Activation energy
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2012.10.089

[Display omitted] ► Ca–Mg–Zn Metallic glasses were prepared using the melt-spinning technique. ► The crystallization was characterized by DSC, XRD and electrical resistivity. ► The glass transition, crystallization and activation energy were determined by DSC. ► The phases from each crystallization stage were identified by Rietveld analysis. ► The composition showing the best glass-forming ability and thermal stability was determined. Metallic glasses in the composition range of Ca4Mg72−xZn24+x (x=0–12, Δx=2) were successfully prepared using the melt-spinning technique. The crystallization characteristics of the alloys were investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and electrical resistance measurements. All samples show a complex crystallization process with four exothermic events. The phases resulting from each crystallization stage were identified by XRD. The crystallization was initiated at lower temperatures by the precipitation of Mg51Zn20 crystals. Mg-hcp and Ca16.7Mg38.2Zn45.1 (IM1) ternary compound precipitated from the retained amorphous phase during the second crystallization event. After that, Ca1.5Mg55.3Zn43.2 (IM4) ternary compound formed at higher temperatures and the crystallization event terminated via IM4 transforming to Ca2Mg5Zn13 (IM3) before melting. All crystallization reactions were found to be in qualitative agreement with the equilibrium phase diagram. The activation energy for each stage of crystallization was determined from DSC analysis and calculated by Kissinger method. The temperature dependence of electrical resistance shows good consistency with DSC and XRD results.