Non-isothermal crystallization kinetics and fragility of Zr56Co28Al16 and Zr56Co22Cu6Al16 bulk metallic glasses
| Autor: | S. M. A. Boutorabi, Morteza Tamizifar, Masoud Mohammadi Rahvard |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Materials science
Amorphous metal Alloy Nucleation Thermodynamics 02 engineering and technology Activation energy engineering.material 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences 010406 physical chemistry 0104 chemical sciences law.invention Fragility Differential scanning calorimetry law engineering Physical and Theoretical Chemistry Crystallization 0210 nano-technology Glass transition |
| Zdroj: | Journal of Thermal Analysis and Calorimetry. 134:903-914 |
| ISSN: | 1588-2926 1388-6150 |
| DOI: | 10.1007/s10973-018-7367-8 |
| Popis: | The role of substitution of Cu for Co on the non-isothermal crystallization kinetics and fragility of Zr56Co28Al16 and Zr56Co22Cu6Al16 bulk metallic glasses (BMGs) were evaluated by differential scanning calorimetry (DSC). The X-ray diffraction, transmission electron microscopy and microhardness test were used to investigate the glassy alloys structure. DSC results exhibited two crystallization processes for both BMGs. All the characteristic temperatures except glass transition temperature of parent alloy were more sensitive to heating rate than those of Cu containing alloy. The activation energies of characteristic temperatures were obtained by Kissinger and Ozawa methods. The results showed that the activation energy of glass transition decreased and the other activation energies increased with Cu addition. Also, the local Avrami exponents at various heating rates were calculated by the Johnson–Mehl–Avrami equation. The n value variations for each crystallization process were in almost similar trends for both BMGs. The results demonstrated that the transformation kinetics is dominated by diffusion-controlled three-dimensional growth with increasing nucleation rate for the first crystallization process and also for initially stage of the second crystallization process. However, the crystallization is dominated by interface-controlled three-dimensional growth with increasing nucleation rate at final stage of the second crystallization processes. In addition, both BMGs were classified into “strong glasses”, depending on the calculated values of fragility index. |
| Databáze: | OpenAIRE |
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