Dynamic crystallization during non-isothermal laser treatment of Fe–Si–B metallic glass

Joshi, Sameehan S.; Gkriniari, Anna V; Katakam, Shravana; Dahotre, Narendra B.

doi:10.1088/0022-3727/48/49/495501

Cited by 28 publications

(6 citation statements)

References 98 publications

(176 reference statements)

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“…The temperature evolutions during laser‐assisted synthesis of the bioglass coatings for various laser processing conditions were estimated, using a COMSOL™‐based finite element (FE) model . The model was constructed within the heat transfer module of the COMSOL™.…”

Section: Experimental and Simulation Processmentioning

confidence: 99%

“…The transient temperature fields developed within the sample during laser beam movement on the sample surface were estimated using Equation . On the top surface of the coating, a spatial Gaussian distribution of heat flux Q x,y,z in the cross section of laser beam is expressed mathematically according to Equation ,

Q_{x, y, z} = \frac{P_{0}}{A} exp [- \frac{{false(x - V t false)}^{2} - y^{2}}{2 {SD}^{2}}]

where t is the time and SD is the standard deviation of the Gaussian beam (0.2 mm in the current case). The heat put in by the laser beam was then dissipated via conduction, convection, and radiation from the top surface as expressed in Equation

- k^{'} [\frac{\partial T}{\partial x} + \frac{\partial T}{\partial y} + \frac{\partial T}{\partial y}] = Q_{x, y, z} - ϵ σ [T^{4} - {T_{0}}^{4}] - h [T - T_{0}],

where ε is the emissivity, h is the convective heat transfer coefficient, σ is the Stephen Boltzman's constant (5.67 × 10 −8 W/m/K 4 ), and T 0 is the ambient temperature (300 K).…”

Section: Experimental and Simulation Processmentioning

confidence: 99%

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Laser coating of bioactive glasses on bioimplant titanium alloys

Kuo

Joshi

et al. 2018

Int J of Appl Glass Sci

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Laser-assisted material processing is a promising field for new material synthesis. This study explores the feasibility of using laser as a tool to synthesize SiO 2 -Na 2 O-CaO-P 2 O 5 bioactive glass coatings on Ti-6Al-4V alloy for bio-implant application. Various laser processing conditions were explored to investigate their effects on coating characteristics. Detailed microstructure and elemental distribution on the top surface and in the cross-sectional region of the bioactive glasscoated alloy were investigated by scanning electron microscope and energy dispersive spectroscopy. Bio-mineralization in simulated body fluid for both representative-coated samples and uncoated control sample for comparison was carried out. The thermokinetic effects during laser processing were simulated using a multi-physics finite element model. The results demonstrated synthesis of bioactive glass coating on the metal substrate with local segregation of Na, P, and Si elements and considerable dilution of Al and Ti in the coating from the alloy substrate impacted the bioactivity of the coating. Although the observations suggest that the laser processing is a promising method in applying bioactive glasses coatings, further efforts are warranted to optimize laser processing conditions to produce adherent coating while retaining its bioactivity. K E Y W O R D S

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Section: Experimental and Simulation Processmentioning

confidence: 99%

Q_{x, y, z} = \frac{P_{0}}{A} exp [- \frac{{false(x - V t false)}^{2} - y^{2}}{2 {SD}^{2}}]

- k^{'} [\frac{\partial T}{\partial x} + \frac{\partial T}{\partial y} + \frac{\partial T}{\partial y}] = Q_{x, y, z} - ϵ σ [T^{4} - {T_{0}}^{4}] - h [T - T_{0}],

where ε is the emissivity, h is the convective heat transfer coefficient, σ is the Stephen Boltzman's constant (5.67 × 10 −8 W/m/K 4 ), and T 0 is the ambient temperature (300 K).…”

Section: Experimental and Simulation Processmentioning

confidence: 99%

Laser coating of bioactive glasses on bioimplant titanium alloys

Kuo

Joshi

et al. 2018

Int J of Appl Glass Sci

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“…Rapid heating rates during laser processing led to a shift in the onset of crystallisation temperature to a higher level. Faster cooling rates prematurely arrested the crystallite growth yielding much finer crystallite sizes (Joshi et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Weld speed effects on quality of Ti/Al dissimilar metal joints using laser beam welding

Kalaiselvan¹,

Elango

Nagarajan

2017

IJASMM

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Laser beam welding produces good quality welds with minimum shrinkage for sheet metal joints. The quality of welded joint depends upon surface morphology, hardness, mixing of liquid phases and metallurgical non-homogeneity induced by gradients of temperatures and cooling rate at the weld interface. In the present investigation, Titanium Grade5 (Ti) and AA2024 (Al) alloy dissimilar sheet metals are joined using Nd:YAG pulsed laser beam and the effect of welding speed on crack tendencies, the strength of weldment based on hardness and composition changes are studied. Test results reveal that higher welding speed eliminates cracks in weldment and improves surface morphology. From hardness test, it is observed that the strength of fusion zone is considerably improved at higher weld speed and the findings are supported by SEM and EDS studies.Keywords: laser beam welding; LBW; morphology; hardness; microstructure; composition.Reference to this paper should be made as follows: Kalaiselvan, K., Elango, A. and Nagarajan, N.M. (2017) N.M. Nagarajan is a retired Professor from National Institute of Technology, Calicut, Kerala, India. His current research deals with powder metallurgy, metal joining, foundry and control of welding processes. He has authored and co-authored more than 100 technical papers.

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“…The peaks corresponding to the crystals, identified to be complex carbides of (Fe,Cr) 23 C 6 41,46 , are observed to exhibit significant broadening which are suggestive of their small sizes. The size of crystals evolved from an amorphous matrix of iron based metallic glass upon thermal processing can be approximately estimated according to the Scherrer equation expressed as 47 :…”

Section: Resultsmentioning

confidence: 99%

Crystallization Mechanism in Spark Plasma Sintered Bulk Metallic Glass Analyzed using Small Angle Neutron Scattering

Paul

Singh

Littrell

et al. 2020

Sci Rep

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Understanding the thermal stability of metallic glasses is critical to determining their safe temperatures of service. In this paper, the crystallization mechanism in spark plasma sintered Fe 48 cr 15 Mo 14 Y 2 c 15 B 6 metallic glass is established by analyzing the crystal size distribution using x-ray diffraction, transmission electron microscopy and in-situ small angle neutron scattering. Isothermal annealing at 700 °C and 725 °C for 100 min resulted in the formation of (Fe,Cr) 23 c 6 crystals, measured from transmission electron micrographs, to be from 10 to 30 nm. The small angle neutron scattering intensity measured in-situ, over a Q-range of 0.02 to 0.3 Å −1 , during isothermal annealing of the sintered samples, confirmed the presence of (Fe,Cr) 23 c 6 crystals. The measured scattering intensity, fitted by the maximum entropy model, over the Q-range of 0.02 to 0.06 Å −1 , revealed that the crystals had radii ranging from 3 to 18 nm. The total volume fraction of crystals were estimated to be 0.13 and 0.22 upon isothermal annealing at 700 °C and 725 °C for 100 min respectively. The mechanism of crystallization in this spark plasma sintered iron based metallic glass was established to be from pre-existing nuclei as confirmed by Avrami exponents of 0.25 ± 0.01 and 0.39 ± 0.01 at the aforesaid temperatures.

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Dynamic crystallization during non-isothermal laser treatment of Fe–Si–B metallic glass

Cited by 28 publications

References 98 publications

Laser coating of bioactive glasses on bioimplant titanium alloys

Laser coating of bioactive glasses on bioimplant titanium alloys

Weld speed effects on quality of Ti/Al dissimilar metal joints using laser beam welding

Crystallization Mechanism in Spark Plasma Sintered Bulk Metallic Glass Analyzed using Small Angle Neutron Scattering

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