Nanocrystallization kinetics and glass forming ability of the Fe{sub 65}Nb{sub 10}B{sub 25} metallic alloy

Journal Article · Sat Dec 01 00:00:00 EST 2007 · Physical Review. B, Condensed Matter and Materials Physics

DOI:https://doi.org/10.1103/PHYSREVB.76.214111· OSTI ID:21052802

Torrens-Serra, J; Rodriguez-Viejo, J; Clavaguera-Mora, M T ^[1]

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1. Grup de Nanomaterials i Microsistemes, Departament de Fisica, Universitat Autonoma de Barcelona, Edifici Cc, 08193 Bellaterra (Spain)

The crystallization kinetics of glassy Fe{sub 65}Nb{sub 10}B{sub 25} melt-spun ribbons is studied by differential scanning calorimetry in the mode of continuous heating and isothermal annealing and by x-ray diffraction and transmission electron microscopy. Continuous heat treatments of the ribbons show the presence of multiple exothermic peaks before melting. The low-temperature peak corresponds to the precipitation of nanoscale Fe{sub 23}B{sub 6}-type crystalline metastable phase, and further annealing leads to its transformation into the metastable Fe{sub 3}B phase and subsequent formation of bcc-Fe, Fe{sub 2}B, and FeNbB stable crystalline phases. The nucleation frequency and the growth rate are determined at selected temperatures from the analysis of the microstructures that emerge during the Fe{sub 23}B{sub 6}-type nanocrystallization. The master curve method is used to obtain the apparent activation energy and the Avrami exponent at the nanocrystallization onset. The nanocrystallization kinetics is explained in the framework of the Kolmogorov-Johnson-Mehl-Avrami theory. The rejection of insoluble alloy atoms during primary crystallization, the formation of diffusion layers around the crystals, and the decrease in the nucleation frequency caused by alloy enrichment of the residual disordered matrix is modeled through a soft impingement factor. Estimated values for the interfacial energy that provide a satisfactory agreement between experiments and modeling are derived considering that homogeneous nucleation frequency and interface-controlled grain growth are dominant at the onset of the nanocrystallization. Consequently, the time-temperature-transformation diagram is also drawn and the critical cooling rate estimated for this glass forming alloy.

• OSTI ID: 21052802
• Journal Information: Physical Review. B, Condensed Matter and Materials Physics, Vol. 76, Issue 21; Other Information: DOI: 10.1103/PhysRevB.76.214111; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ACTIVATION ENERGY
ANNEALING
BCC LATTICES
BORON ALLOYS
CRYSTALLIZATION
GLASS
GRAIN GROWTH
IRON ALLOYS
IRON BORIDES
KINETICS
LAYERS
MELTING
MICROSTRUCTURE
NANOSTRUCTURES
NIOBIUM ALLOYS
NUCLEATION
PRECIPITATION
TEMPERATURE RANGE 0065-0273 K
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION