Combined in situ synchrotron micro X-ray diffraction and high-speed imaging on rapidly heated and solidified Ti–48Al under additive manufacturing conditions

Kenel, Christoph; Grolimund, Daniel; Fife, Julie L.; Samson, Vallerie Ann; Petegem, S. Van; Swygenhoven, H. Van; Leinenbach, Christian

doi:10.1016/j.scriptamat.2015.12.009

Cited by 51 publications

(29 citation statements)

References 11 publications

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“…Previous investigations of γ-TiAl alloys suggested that the peritectic α nucleates from the melt and not at the parent β matrix 37 , 38 . Accordingly, formation of α from liquid via L → L + α transformation was shown to take place during fast solidification (1.25∙10 3 °C s −1 ) of a Ti-48 at.% Al alloy 39 . This implies that the formation of new α orientations is related to its own preferential growth direction and not to that of the parent β phase.…”

Section: Resultsmentioning

confidence: 97%

Peritectic titanium alloys for 3D printing

et al. 2018

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Metal-based additive manufacturing (AM) permits layer-by-layer fabrication of near net-shaped metallic components with complex geometries not achievable using the design constraints of traditional manufacturing. Production savings of titanium-based components by AM are estimated up to 50% owing to the current exorbitant loss of material during machining. Nowadays, most of the titanium alloys for AM are based on conventional compositions still tailored to conventional manufacturing not considering the directional thermal gradient that provokes epitaxial growth during AM. This results in severely textured microstructures associated with anisotropic structural properties usually remaining upon post-AM processing. The present investigations reveal a promising solidification and cooling path for α formation not yet exploited, in which α does not inherit the usual crystallographic orientation relationship with the parent β phase. The associated decrease in anisotropy, accompanied by the formation of equiaxed microstructures represents a step forward toward a next generation of titanium alloys for AM.

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Section: Resultsmentioning

confidence: 97%

Peritectic titanium alloys for 3D printing

et al. 2018

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“…High-speed camera imaging with 500 Hz frame rate is performed 45° off-axis with respect to the X-ray beam direction. Based on the recorded intensity, temperature is calculated based on a radiation model and camera calibration 23 . The temperature distribution on the surface as well its evolution upon cooling provides information about thermal gradients and obtained cooling rates.…”

Section: Resultsmentioning

confidence: 99%

“…The temperature is calculated from the measured intensity on the CCD sensor according to ref. 23 where I CCD is the intensity on the CCD chip, is the first radiation constant with being the Planck constant and being the speed of light in vacuum, is the second radiation constant with k being the Boltzmann constant, T is the temperature and a = 7.95·10 22 W −1 ·m −2 and b = 7.32·10 −7 m are the camera-dependent parameters.…”

Section: Methodsmentioning

confidence: 99%

In situ investigation of phase transformations in Ti-6Al-4V under additive manufacturing conditions combining laser melting and high-speed micro-X-ray diffraction

Kenel

Grolimund

et al. 2017

Sci Rep

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125

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We present combined in situ X-ray diffraction and high-speed imaging to monitor the phase evolution upon cyclic rapid laser heating and cooling mimicking the direct energy deposition of Ti-6Al-4V in real time. Additive manufacturing of the industrially relevant alloy Ti-6Al-4V is known to create a multitude of phases and microstructures depending on processing technology and parameters. Current setups are limited by an averaged measurement through the solid and liquid parts. In this work the combination of a micro-focused intense X-ray beam, a fast detector and unidirectional cooling provide the spatial and temporal resolution to separate contributions from solid and liquid phases in limited volumes. Upon rapid heating and cooling, the β ↔ α′ phase transformation is observed repeatedly. At room temperature, single phase α′ is observed. Secondary β-formation upon formation of α′ is attributed to V partitioning to the β-phase leading to temporary stabilization. Lattice strains in the α′-phase are found to be sensitive to the α′ → β phase transformation. Based on lattice strain of the β-phase, the martensite start temperature is estimated at 923 K in these experiments. Off-axis high speed imaging confirms a technically relevant solidification front velocity and cooling rate of 10.3 mm/s and 4500 K/s, respectively.

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“…In situ synchrotron X-ray micro-beam-diffraction during rapid solidification was conducted at the microXAS beamline at the Swiss Light Source (SLS), Switzerland using the experimental setup for rapid solidification tests described in previous works [ 12 , 31 ]. Spheres of 0.5 mm radius corresponding to a cooling rate of 11,000 K s −1 were placed on a Cu tip for maximization of heat extraction and molten by two inclined diode lasers (λ = 980 nm) with an angle of 20° on two sides.…”

Section: Methodsmentioning

confidence: 99%

In Situ and Ex Situ Characterization of the Microstructure Formation in Ni-Cr-Si Alloys during Rapid Solidification—Toward Alloy Design for Laser Additive Manufacturing

Zweiacker

Grolimund

et al. 2020

Materials

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Laser beam-based deposition methods such as laser cladding or additive manufacturing of metals promises improved properties, performance, and reliability of the materials and therefore rely heavily on understanding the relationship between chemical composition, rapid solidification processing conditions, and resulting microstructural features. In this work, the phase formation of four Ni-Cr-Si alloys was studied as a function of cooling rate and chemical composition using a liquid droplet rapid solidification technique. Post mortem x-ray diffraction, scanning electron microscopy, and in situ synchrotron microbeam X-ray diffraction shows the present and evolution of the rapidly solidified microstructures. Furthermore, the obtained results were compared to standard laser deposition tests. In situ microbeam diffraction revealed that due to rapid cooling and an increasing amount of Cr and Si, metastable high-temperature silicides remain in the final microstructure. Due to more sluggish interface kinetics of intermetallic compounds than that of disorder solid solution, an anomalous eutectic structure becomes dominant over the regular lamellar microstructure at high cooling rates. The rapid solidification experiments produced a microstructure similar to the one generated in laser coating thus confirming that this rapid solidification test allows a rapid pre-screening of alloys suitable for laser beam-based processing techniques.

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Combined in situ synchrotron micro X-ray diffraction and high-speed imaging on rapidly heated and solidified Ti–48Al under additive manufacturing conditions

Cited by 51 publications

References 11 publications

Peritectic titanium alloys for 3D printing

Peritectic titanium alloys for 3D printing

In situ investigation of phase transformations in Ti-6Al-4V under additive manufacturing conditions combining laser melting and high-speed micro-X-ray diffraction

In Situ and Ex Situ Characterization of the Microstructure Formation in Ni-Cr-Si Alloys during Rapid Solidification—Toward Alloy Design for Laser Additive Manufacturing

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