Metallurgical and Materials Transactions A

Journal Information
ISSN / EISSN: 10735623 / 15431940
Published by: Springer Nature
Total articles ≅ 18,314

Latest articles in this journal

, Mehmet Can Uçgun, Ali Günen
Published: 8 December 2022
Metallurgical and Materials Transactions A pp 1-17; https://doi.org/10.1007/s11661-022-06915-8

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, Ł. Żrodowski, B. Morończyk, Ł. Maj, A. Kuś, T. Lampke
Published: 8 December 2022
Metallurgical and Materials Transactions A pp 1-13; https://doi.org/10.1007/s11661-022-06913-w

Abstract:
Selective laser melting (SLM) is one of the promising techniques for producing metallic glass components with unlimited geometries and dimensions. In the case of iron-based metallic glasses, the appearance of cracks remains a problem. In this work, two alloys Fe48Mo14Cr15Y2C15B6 and (Fe0.9Co0.1)76Mo4(P0.45C0.2B0.2Si0.15)20, differing in their plasticity, were printed with a double stage scanning strategy. Both alloys were characterized by a fully amorphous structure and a crack grid that coincided with the hatch distance in the first scan. Segregations of metalloids were observed in the vicinity of the cracks. Fe48Mo14Cr15Y2C15B6 samples were characterized by a high compression strength of 1298 ± 11 MPa and zero plasticity. The compression strength of the (Fe0.9Co0.1)76Mo4(P0.45C0.2B0.2Si0.15)20 samples was 142 ± 22 MPa. The results obtained suggest that further development of scanning strategies and research on the influence of alloying elements is needed.
, Gianluca Fiore, Livio Battezzati
Published: 6 December 2022
Metallurgical and Materials Transactions A pp 1-10; https://doi.org/10.1007/s11661-022-06907-8

Abstract:
In this work, melt-spun ribbons of AlSi10Mg added with modifiers (Er, Sr, or nano-TiB2) were produced to investigate the combined effect of modification and rapid solidification on eutectic Si. The resulting eutectic microstructures are more isotropic in comparison to that of the base alloy affecting the mechanical properties of the alloys. The modification of Si morphology and supersaturation caused by the modifiers were investigated by microscopy, X-ray diffraction, and differential scanning calorimetry. Compared to melt-spun AlSi10Mg, the eutectic Si network is finer and less continuous when Er or Sr is added, and disrupted with rounded crystals dispersed in the matrix when adding nano-TiB2. The level of supersaturation decreases in the order Er–nano-TiB2–Sr. A transition from columnar Al grains at the wheel side to finer equiaxed grains at the air side was found in the unmodified ribbon and in the one containing nano-TiB2 by means of electron backscattered diffraction. The Er- and Sr-modified ribbons display equiaxed Al grains of constant size throughout their thickness. The average hardness obtained by nano-indentation tests was lower than that of AlSi10Mg. The less continuous Si network causes the hardness drop but provides more isotropic mechanical properties.
Jaclyn L. Cho,
Published: 6 December 2022
Metallurgical and Materials Transactions A pp 1-10; https://doi.org/10.1007/s11661-022-06900-1

Abstract:
In V45Ti30Ni25 (at. pct), superelastic TiNi and a stable V-rich bcc phase (β) coexist in multiple-phase mixtures with each acting as matrix and precipitate. Through nano-indentation measurements and in situ synchrotron and SEM tensile tests coupled with digital image correlation analysis, the phase mixtures are revealed to exhibit similar strain-partitioning behaviors but different dependencies of reverse transformation on strain. These insights on multi-phase plasticity provide hints for improved damage resistance in the presence of a superelastic phase.
, Miroslav Husťák, Jitka Hegrová, Roman Gröger
Published: 5 December 2022
Metallurgical and Materials Transactions A pp 1-11; https://doi.org/10.1007/s11661-022-06866-0

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, Wei Li, Changle Li, Song Lu, Levente Vitos, Florian Pyczak
Published: 5 December 2022
Metallurgical and Materials Transactions A pp 1-14; https://doi.org/10.1007/s11661-022-06891-z

Abstract:
First-principles calculations were performed to investigate the elastic and thermodynamic properties for multi-component Co-based superalloy systems and explored the effect of alloying on stabilizing the γ′ phase. First, the comparisons were carried out for the γ′ phase in Co3(Al,TM) (TM being transition metals) and Ni3Al systems between the present computational results using the EMTO-CPA method and other available DFT calculations as well as experimental data. The lattice parameters, elastic constants, and Debye temperatures are consistent with experimental results and other calculations. The predicted thermodynamic properties, e.g., the Gibbs free energy, excess entropy, and linear thermal expansion coefficient, agree well with CALPHAD results, experimental results, and other available first-principles calculations. A combination of EMTO-CPA method and Debye–Grüneisen model is utilized in this work to ensure that the alloying effect on the stability of the γ′ phase in a multi-component Co-based system is captured efficiently. This could open the path for designing novel multi-component Co-based alloys based on first-principles calculation. To demonstrate this, predictions for the properties of multicomponent systems were undertaken. Our results show that Ni aids in the stabilization of the (CoNi)3(Al, Mo, Nb) phase. Graphical Abstract
, L. P. Freund, A. Förner, J. Völkl, L.-K. Huber, M. Göken, S. Neumeier
Published: 3 December 2022
Metallurgical and Materials Transactions A pp 1-12; https://doi.org/10.1007/s11661-022-06912-x

Abstract:
Recent studies revealed the excellent high temperature properties of polycrystalline CoNi-base superalloys. However, their underlying deformation behavior has been reported only scarcely so far. In this work, the deformation mechanisms of four polycrystalline compositionally complex CoNi-base superalloys with slightly varying chemical compositions were investigated by compression and creep experiments at temperatures between 750 °C and 850 °C and strain-rates between 10–3 and 10–8 s−1. In the two (Ta + Ti)-rich alloys, a transition of the deformation mechanism from shearing by APB-coupled dislocation pairs to stacking fault shearing and finally also to microtwinning is observed with decreasing strain-rate and increasing temperature. In contrast, APB-based shearing mechanisms represent the dominant mechanism in both (Al + W)-rich alloys in all conditions. At high temperatures and low strain-rates, dislocation glide-climb processes also contribute to plastic deformation in all alloys. By correlating the underlying defect structures with the mechanical properties of these alloys, it becomes evident that a transition to stacking fault shearing and microtwinning leads to a lower strain-rate dependency and superior high-temperature strength in comparison with APB-based mechanisms. Reasons for the different deformation mechanisms, the influence of segregation processes, the consequences for mechanical properties and implications for a mechanism-based alloy design are discussed.
Robert Josef Enzinger, Martin Luckabauer, Norihiko L. Okamoto, Tetsu Ichitsubo, Wolfgang Sprengel,
Published: 30 November 2022
Metallurgical and Materials Transactions A pp 1-14; https://doi.org/10.1007/s11661-022-06881-1

Abstract:
A detailed understanding of the kinetics of phase formation in $$\beta $$β -stabilised titanium is of decisive importance for the applicability of these materials. However, the complex nature and long timescales of the various transformations, calls for specialized measurement techniques. In this work high-stability isothermal laser dilatometry is used to study the temporal volume changes associated with the various phase formation processes. Distinctly different behaviours between samples of Ti–21 at. pct V with different solute oxygen content could be detected and quantified. Temperature regimes for both diffusionless and diffusion-assisted isothermal $$\omega $$ω -formation as well as for $$\omega $$ω -to- $$\alpha $$α -transformation were determined. Low oxygen contents promote the diffusionless $$\omega $$ω -formation mechanism, but retard the diffusion-assisted one as well as the $$\omega $$ω -to- $$\alpha $$α -transformation process. The results confirm recent findings of a clear distinction between the diffusionless and diffusion-assisted isothermal $$\omega $$ω formation modes. Modelling of the $$\omega $$ω -phase formation applying Austin–Rickett kinetics revealed the temperature-dependent formation rates, on the basis of which the isothermal TTT-diagrams were developed which reflect the strong influence of the oxygen content.
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