Microstructural State Research Articles

Design Sr, Mn-doped 3DOM LaCoO3 perovskite catalysts with excellent SO2 resistance for benzene catalytic combustion

Anti SO2 poisoning is a major scientific challenge in the field of VOCs catalytic combustion. To enhance sulfur resistance of 3DOM LaCoO3 perovskite catalysts, the strontium (Sr) and manganese (Mn) elements were doped to regulate and control its microstructure and electronic valence states of active metals. The macropore structure is constructed to accelerate the adsorption and diffusion of benzene and intermediate species and promote the deep oxidation in ordered macropores. Surprisingly, we observed that the co-doping of Sr and Mn components resulted in the superior catalytic performance for benzene catalytic combustion. Especially, the sulfur resistance of LaCoO3 catalyst was significantly improved due to the doping of Sr and Mn species. Through various characterizations, it is discovered that the doping of Mn component in 3DOM LaCoO3 perovskite catalyst could promote the formation of active Co3+ species due to the excellent redox properties between Mn&+ and Co&+ species (Mn4++Co2+→Mn3++Co3+), while the co-doping of Sr and Mn elements could produce and form some new active species. On one hand, Sr and Mn may act as an electron promoter to increase the concentration of Co3+ and Oads. On the other hand, Sr and Mn can act as a structure promoter to enhance the specific surface area and promote the dispersion of active Co species. The research provides valuable reference for the development of highly efficient catalysts for the industrial degradation of benzene.

Fresh, mechanical and microstructural behaviour of high-strength self-compacting concrete using supplementary cementitious materials

Sustainable practices in the construction sector have become a major issue due to the overuse of natural raw materials. Industrial by-products like fly ash (FA), silica fume (SF), and marble powder (MP) incorporation in concrete production will be assessed in this paper in terms of fresh, mechanical, and microstructural states. Consequently, this study proposes an in-depth investigation of SCMs applied with varied substitute cement amounts, looking at components like MP, SF, and FA. The impacts on fresh characteristics of HSSCC were assessed using slump flow, V-funnel time, T50 time, L-box ratio, and J-ring slump flow. Compressive, flexural, and splitting tensile strength tests were performed to analyze the mechanical properties. Energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscope (SEM) techniques were used for the microstructural examination of HSSCC. It has been found that SCMs, including MP, FA, and SF, may enhance the characteristics of concrete. The slump flow values, which indicate the flowability and filling ability of HSSCC, were improved by a maximum of 9.6 % for 20 % SF and 10 % for both FA and MP replacement. The most promising outcomes on the basis of mechanical operation were gained by using SF, MP, and FA in HSSCC at respective percentages of 20 %, 10 %, and 10 %. This mixture revealed an increase in compressive strength of a maximum of 15 % at 56 days compared to the control mixture, which contained 10 % MP. However, the excessive addition of MP negatively impacted the strength of the concrete. The EDS examination illustrated that the ‘Ca’ to ‘Si’ proportion in HSSCC significantly affects the emergence of strength. This study will enlighten users during the preparation of high-strength self-compacting concrete (HSSCC) by replacing ordinary Portland cement (OPC) with different available supplementary cementitious material (SCM) combinations.

Characterization and constitutive analysis-based crystal plasticity of warm flow and fracture behaviours of 2060 Al–Cu–Li alloy

AA2060-T8 is a relatively new Al–Cu–Li alloy developed in the last few years as a lightweight alternative to conventional Al alloys. Thus, it is essential to characterize the warm flow, fracture, and anisotropic behaviours of this alloy and propose constitutive analysis-based crystal plasticity (CP) modelling to link its mechanical behaviour with the microstructural state. Therefore, in this study, isothermal warm tensile tests were conducted using a Gleeble-3800 thermomechanical simulator and different sample orientations at temperatures and strain rates varying from 373 to 573 K and 0.001–0.1 s−1, respectively. The tensile behaviour of the 2060 Al–Cu–Li alloy sheet depends on the sample orientations, which results in significant anisotropy. The anisotropic degree of the tensile properties of this alloy was significantly reduced by increasing the forming temperature above 473 K. In addition, the fracture behaviours of 2060 Al–Cu–Li sheets were transformed from mixed ductile-brittle fracture mode to ductile fracture mode by decreasing strain rates and increasing the temperatures, respectively. Afterward, a novel crystal plasticity model was proposed to describe the grain behaviour and the deformation mechanism of 2060 Al–Cu–Li alloy under warm forming conditions. The developed constitutive model was implemented using the monolithic time-integration algorithm-based backward Euler method. The results acquired from the proposed constitutive analysis agree well with those obtained from experimentation in all testing conditions. This indicates its ability to accurately predict the warm flow behaviour of 2060 Al–Cu–Li alloy under different strain rates and loading directions.

Development of AI based analysis tools for online monitoring of steel-making process

Mechanical properties of steel are closely monitored during the manufacturing process through various non-destructive techniques. The IMPOC device implements one of them and is used by steel manufacturers at several locations of the production line. It provides a fast electromagnetic measurement that is strongly correlated with the microstructural state of the steel, hence its use to check online the uniformity of the semi-final or final product. Tata Steel, CEA LIST and SSSA have worked together to analyse IMPOC datasets corresponding to various situations in terms of steel coils and process conditions. A data driven model has been built from field measurements using a specific neural network architecture. This model proves useful to investigate the complex relations between numerous process parameters and the IMPOC value. This communication presents the approach followed to build the data driven model using neural networks and to check its relevance. The relationship between the measurement on one side and the process parameters and material composition on the other side are then investigated by means of several sensitivity analysis and feature importance techniques.

Electrospinning of pullulan-based orodispersible films containing sildenafil

Feasibility of electrospinning in the manufacturing of sildenafil-containing orodispersible films (ODFs) intended to enhance oxygenation and to reduce pulmonary arterial pressure in pediatric patients was evaluated. Given the targeted subjects, the simplest and safest formulation was chosen, using water as the only solvent and pullulan, a natural polymer, as the sole fiber-forming agent. A systematic characterization in terms of shear and extensional viscosity as well as surface tension of solutions containing different amounts of pullulan and sildenafil was carried out. Accordingly, electrospinning parameters enabling the continuous production, at the highest possible rate, of defect-free fibers with uniform diameter in the nanometer range were assessed. Morphology, microstructure, drug content and relevant solid state as well as ability of the resulting non-woven films to interact with aqueous fluids were evaluated. To better define the role of the fibrous nanostructure on the performance of ODFs, analogous films were produced by spin- and blade-coating and tested. Interestingly, the disintegration process of electrospun products turned out to be the fastest (i.e. occurring within few s) and compliant with Ph. Eur. and USP limits, making relevant ODFs particularly promising for increasing sildenafil bioavailability, thus lowering its dosages.

Finite element and experimental analysis of grain refinement caused by dynamic recrystallization during high-speed cutting of nickel-based superalloys

Nickel-based superalloys are subjected to complex mechanical and thermal loads during high-speed cutting, resulting in dynamic recrystallization behavior. The microstructure state is closely related to fatigue performance. In this paper, the Johnson-Mehl-Avrami-Kolmogorov model is used to predict the microstructure evolution of during high-speed cutting of superalloy GH4169. The finite element model of microstructure evolution considering dynamic recrystallization is established by user-defined subroutine on simulation platform. The error of cutting force obtained by experiment and simulation is within 12%. Serrated chips are obtained in high-speed cutting of superalloy GH4169. The typical characteristics of serrated chips such as peak, valley and peak-to-peak distance obtained by simulation are used to compare with the experimental results, and the error is within 20%. The dynamic recrystallization grain size increases as cutting speed increases. The promoting effect of increasing temperature on grain growth is greater than that inhibition effect of increasing strain rate, which leads to the increase of average grain size of machined surface.

Surface State Induced Filterless SWIR Narrow-Band Si Photodetector

In this letter, planar type self-powered short-wavelength infrared narrowband Si photodetector was realized based on a simple Schottky structure by increasing surface states and enlarging the distance between Schottky electrode and light irradiation region. With the assistance of pyramid microstructure, the distance needed for sub-100 nm narrowband detection effectively decreased from 1000 μ m to 200 μ m, which is vital to improving device sensitivity and reducing device size. The obtained photodetector exhibited a response peak at 1119 nm with full-width at half-maximum of 97 nm. At zero bias, a peak detectivity up to 2.25 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> Jones, linear dynamic range of 91 dB and fast response speed (Rise time of 88 μ s and fall time of 118 μ s) were achieved. The higher wavelength selectivity and sensitivity than its counterpart with flat surface should be ascribed to the large number of surface state and pronounced light confinement effect of pyramid microstructure. This work opens up a new avenue for achieving planar-type narrowband photodetector that can provide better integration capabilities for on-chip applications than vertical devices.

Effects of elevated temperature exposure on the residual stress state and microstructure of PVD Cr coatings on SiC investigated via in situ X-ray diffraction and transmission electron microscopy

Pure Cr coatings are being considered as corrosion-resistant layers for SiC-SiCf composite fuel cladding in light water reactors. The residual stress state and interdiffusion behavior of Cr coatings deposited on SiC substrates using bipolar high-power impulse magnetron sputtering (B-HiPIMS) and direct current impulse magnetron sputtering (DCMS) were studied using in situ X-ray diffraction experiments at 300 °C, 700 °C, and 1200 °C. After elevated temperature exposure, evolution of the coating microstructure and coating/substrate interdiffusion was characterized by transmission electron microscopy. The compressive residual stress of the dense B-HiPIMS coating at room temperature was gradually relieved at 300 °C, while the stress transitioned to a tensile state at 700 °C. Grain growth of the Cr coating and a Cr–SiC interdiffusion layer consisting of newly formed Cr–C and Cr–Si phases were observed in the B-HiPIMS coating after exposure at 700 °C. The phases in the interdiffusion layer were identified to be Cr7C3, Cr3Si, and Cr5Si3Cx experimentally and by thermodynamic predictions. For the DCMS coating, however, changes in residual stress and microstructure at the elevated temperatures were limited by the inherent porosity and inhomogeneous structure of the as-deposited coating. At 1200 °C, both coating types interacted rapidly with the underlying SiC substrate in the early stages of the experiment. The results from this study suggest that the characteristics of the Cr coatings do not significantly change at the reactor operating temperature of 300 °C, while changes in microstructure and stress state are expected in off-normal conditions of 700 °C and 1200 °C. The results from this study suggest the B-HiPIMS coating is best-suited as a protective coating for SiC fuel cladding.

Functional Tailoring of Multi-Dimensional Pure MXene Nanostructures for Significantly Accelerated Electromagnetic Wave Absorption.

Transition metal carbide (Ti3 C2 Tx MXene), with a large specific surface area and abundant surface functional groups, is a promising candidate in the family of electromagnetic wave (EMW) absorption. However, the high conductivity of MXene limits its EMW absorption ability, so it remains a challenge to obtain outstanding EMW attenuation ability in pure MXene. Herein, by integrating HF etching, KOH shearing, and high-temperature molten salt strategies, layered MXene (L-MXene), network-like MXene nanoribbons (N-MXene NRs), porous MXene monolayer (P-MXene ML), and porous MXene layer (P-MXene L) are rationally constructed with favorable microstructures and surface states for EMW absorption. HF, KOH, and KCl/LiCl are used to functionalize MXene to tune its microstructure and surface state (F- , OH- , and Cl- terminals), thereby improving the EMW absorption capacity of MXene-based nanostructures. Impressively, with the unique structure, proper electrical conductivity, large specific surface area, and abundant porous defects, MXene-based nanostructures achieve good impedance matching, dipole polarization, and conduction loss, thus inheriting excellent EMW absorption performance. Consequently, L-MXene, N-MXene NRs, P-MXene ML, and P-MXene L enable a reflection loss (RL ) value of -43.14, -63.01, -60.45, and -56.50dB with a matching thickness of 0.95, 1.51, 3.83, and 4.65mm, respectively.

Coupling Computational Homogenization with Crystal Plasticity Modelling for Predicting the Warm Deformation Behaviour of AA2060-T8 Al-Li Alloy.

This study aimed to propose a new approach for predicting the warm deformation behaviour of AA2060-T8 sheets by coupling computational homogenization (CH) with crystal plasticity (CP) modeling. Firstly, to reveal the warm deformation behaviour of the AA2060-T8 sheet, isothermal warm tensile testing was accomplished using a Gleeble-3800 thermomechanical simulator at the temperatures and strain rates that varied from 373 to 573 K and 0.001 to 0.1 s-1. Then, a novel crystal plasticity model was proposed for describing the grains' behaviour and reflecting the crystals' actual deformation mechanism under warm forming conditions. Afterward, to clarify the in-grain deformation and link the mechanical behaviour of AA2060-T8 with its microstructural state, RVE elements were created to represent the microstructure of AA2060-T8, where several finite elements discretized every grain. A remarkable accordance was observed between the predicted results and their experimental counterparts for all testing conditions. This signifies that coupling CH with CP modelling can successfully determine the warm deformation behaviour of AA2060-T8 (polycrystalline metals) under different working conditions.

Creep damage in 9-12% Cr steel notched components: Microstructural evolution and stress state dependence

To understand the stress state dependent creep damage, following creep tests in 9–12% Cr steel notched components with different root radii, a study of associated time dependent microstructural evolution is presented in this work. Particular attention is paid to the dependence of creep damage evolution on the stress state. The average creep strain of notched component exhibits a typical three-stage characteristic (transient, steady and tertiary stages). During the transient stage, remarkable re-distribution in stress state (equivalent stress and stress triaxiality) is found. The rapid relaxation of equivalent stress near the notch root, associated with the initial coarsening of substructure would delay the nucleation or growth of cavity. By contrast, the time-dependent increase of equivalent stress combined with the relatively high stress triaxiality seems to be responsible for the higher cavity density at the center of notched component. The precipitate coarsening is heterogeneous and promoted by the high level of equivalent stress or stress triaxiality. During the steady stage, the creep damage behavior is related to the magnitude of stress state. Higher cavity density and greater reduction in hardness are mainly found in the region where both the equivalent stress and stress triaxiality are high. As a whole, both the redistribution process of stress states and their levels exhibit significant influence on microstructural evolution and creep damage behavior of notched components at elevated temperatures.

The microstructural and mechanical behavior of in-situ synthesized ZrB2–ZrC and ZrB2–SiC–ZrC composites: A comparative study

In the present investigation, the ZrB2–ZrC and ZrB2–SiC–ZrC based composites were fabricated via an in-situ reduction mechanism using ZrO2, B4C, Si, and graphite fine powder at 1900 °C in an argon atmosphere. The boro/carbothermal reduction produced nano-sized ZrC grains with ZrB2 particles, whereas the incorporation of Si content produced nano-sized homogeneous distributed SiC grains with ZrB2–ZrC particles. In the ZrB2-based composite densification, microstructure, mechanical, and chemical state identification of elements were investigated. The densification of the samples was enhanced with the formation of ZrC and SiC content, which was correlated with the micrographs and mechanical properties of the samples. The chemical state identification confirms the trace amount of intermediate zirconium oxycarbide in the ZrB2-based composite. Compared to binary ZrB2–ZrC composite, ZrB2–SiC–ZrC composite has finer microstructure and higher densification. The strength of the ZrB2–ZrC and ZrB2–SiC–ZrC composite was decreased by 458 MPa and 406 MPa, respectively. Similarly, the indentation hardness of the samples was increased by 14.2 GPa–15.3 GPa, and fracture toughness was 5.5 ± 0.5 MPa m1/2 to 6.15 ± 0.4 MPa m1/2.

Impact of vanadium substitution on structural, magnetic, microwave absorption features and hyperfine interactions of SrCo hexaferrites

The Co-V co-substituted nano Sr-hexaferrite, Sr0.5Co0.5VxFe12−xO19 (0.00 ≤ x ≤ 0.08) (V→SrCo (0.00 ≤ x ≤ 0.08) NHFs), were manufactured by citrate combustion route. The microstructure, morphology, magnetic features, hyperfine interactions and oxidation state and chemical composition of products explained by XRD, SEM with EDX, HR-TEM, VSM, Mossbauer spectrometry, and XPS, respectively. The DXRD (Average crystallite size) of products were assessed via Scherrer formula as within the range of 37 and 83 nm. The hexagonal morphology and chemical composition of the products was presented by TEM, HR-TEM, SEM and EDX analyses. The XPS analysis provided both the composition and oxidation states of prepared NHFs. Mossbauer spectra showed that the s electron density around Fe3+ ions of all sites except 12k influenced V3+ content. The coercivity data indicates that all samples denote a magnetically hard material at both low and high temperatures. Ms, Mr and nB fluctuate with respect to dopant concentration and attain their highest magnitudes for the V→SrCo (x = 0.04) NHFs. A SQR of around 0.5 is achieved at each temperature, reflecting a relatively high large anisotropy field. The field-cooling (FC) curves of all samples yield a drop in magnetization with increasing temperature. Their irreversibility temperature is detected to be beyond 325 K. Both M-H and M-T imply the ferrimagnetic behavior of different samples. Microwave properties were measured between 2 and 18 GHz as S11-S21 parameters. It demonstrated non-linear behavior of the microwave properties vs. V concentration. The origin of the reflection losses in NHVs can be explained by the dipole polarization processes.

Full-scale sustainable structural concrete containing high proportions of by-products and waste

The construction industry in general is, through minor low-cost processing methods, converting several of its by-products into viable materials; furthermore, some siderurgic sector by-products are likewise of use. In this context, large-scale batches (mix volumes over 0.5 m3) of good quality structural concrete are proposed, in which two kinds of binder and two kinds of aggregate (steel slag and recycled concrete) are used to perform four concrete mixtures, containing more than 80 % in mass of good-quality recycled materials. A batch of tests, both in the fresh and in the hardened state, are performed, covering on-site placement and long-term properties, to guarantee the suitability and the quality of the mixtures as structural concretes. Most of the results were encouraging, mainly depending on the aggregate and the binder types that were used. The fresh-state workability of all the test mixtures was good. All the results in terms of hardened properties, strength (42 MPa in type I cement mixtures, and 32–38 MPa in type III cement mixtures), stiffness, long-term shrinkage, and microstructural state (porosity, permeability) were acceptable, their quality depending on the type of each component. The good results of the mixtures based on the slag-based binder deserve attention. Some weak points found were the slightly higher specific weight of the slag aggregate mixes (amounting to more than 2.7 Mg/m3), plastic shrinkage rates (in some cases greater than 1.2–1.5 thousand), and loss of resistance against chlorine penetration in recycled concrete mixes. However, drawbacks of that sort are no obstacle to their use in most structural applications.

Investigation of coordinated behavior of deformation at the interface of Cu–Al laminated composite

To understand the differences between the microstructure and stress states owing to uncoordinated deformation in different regions of a Cu–Al contact interface, the normal stress distribution at the contact interface of the Cu–Al composites and the Al metal adhesion on the peeling surface of the Cu layer are investigated by performing numerical simulations and experimental studies. The results show that the percentage of Al metal adhered to the Cu side gradually increased from the edge to the central region. This is mainly because the central area of the contact interface bore a larger normal stress than the edge position, and when the interface normal stress exceeded 470 MPa, the pressure threshold value required for the extrusion of virgin metal from the surface-hardened layer on the Al side was satisfied. The effect of the initial Cu:Al thickness ratio on the degree of interfacial coordination is investigated, and the degree of coordination of the contact interface was observed to improve and then worsen with the increase in the initial Cu:Al thickness ratio (from 3:9 to 8:4). For composites with a Cu:Al thickness ratio of 4:8, the interface was well coordinated, and the bond strength reached 6.13 MPa, corresponding to a 173.7% improvement compared with the Cu–Al composite with more severe stress concentration (8:4).

MONITORING FEATURES OF FORMING THE CONNECTION OF THIN-WALLED STRUCTURES MADE OF TITANIUM ALLOYS BY DIFFUSION WELDING (REVIEW)

The results of the analysis with an assessment of the features of the formation of products from thin-walled sheet structures made of titanium alloys using diffuse welding (DS) technologies are presented. The analysis of the development of low- and high-temperature deformation in the contact zone at the DS of titanium thin-walled three-layer structures of the T-type is carried out, taking into account the ratio of the thickness of the welded work pieces and their initial microstructure. The estimated data on the influence of the technological parameters of the DS and the micro-structural state of the welded titanium billets on the kinetics of the development of the formation of the welded joint and its mechanical properties are given.

Numerical Simulation of the Taylor Impact Test for Laser Powder Bed Fusion Parts Based on Microstructural Internal State Variables

The response of any engineering design components to stresses should be predictable, While the response of a material to complex loading, such as high strain rates experienced during service, is difficult to represent with simple tests, the Taylor impact test is one of a number of tests devised for high strain rate complex loading. To expedite the acceptance of LPBF Ti6Al4V (ELI) for use in demanding structural applications, there is a need to develop numerical models based on the internal microstructural state variables to predict the performance of the alloy over a wide range of high strain rates using such complex tests. This paper documents the numerical simulation of Taylor impact tests for direct metal laser-sintered and post-processed Ti6Al4V (ELI—Extra Low Interstitial) alloy. A microstructural variable-based constitutive model was used to predict the mechanical properties (stresses and evolution of plastic strains) of the material. The corresponding material parameters of the model were based on the specific microstructure obtained upon post-process heat treatment. The model was first implemented as a user material subroutine in the explicit finite element program ABAQUS using the VUHARD subroutine. Subsequently, the symmetrical Taylor impact tests of Laser Powder Bed Fusion (LPBF) Ti6Al4V (ELI) parts were numerically simulated using the VUHARD subroutine at different impact velocities. The equivalent von Mises stress and plastic strain obtained from numerical simulations were compared with the analytical solutions based on the strain rates obtained. It was shown that the instantaneous and average absolute errors between the numerical and analytical values of the model were generally less than 5%. The mushroom end, commonly observed in a Taylor test specimen, was also seen in the numerical model.

Controllable surface reconstruction of copper foam for electrooxidation of benzyl alcohol integrated with pure hydrogen production

AbstractElectrocatalytic water splitting that is coupled with electrocatalytic chemical oxidation is considered as one of the promising methods for efficiently obtaining hydrogen energy and fine chemicals. Herein, we focus on an electrochemical redox activation strategy to rationally manipulate the microstructure and surface valence states of copper foam (CF) and boost the corresponding performance towards electrocatalytic benzyl alcohol oxidation (EBA), accompanied by the efficient hydrogen production. Correspondingly, the Cu(II)‐dominated species are gradually formed on the CF surface with the dissolution and redeposition of copper in the suitable potential range. The new species containing Cu2O, CuO, and Cu(OH)2 during surface reconstruction process of the CF were confirmed by multiple characterization techniques. After 220‐cycled activation (CF‐220), the activated CF achieves an increase of current density for EBA in anode from 9.5 for the original CF to 29.3 mmol/cm2, while the pure hydrogen yield increases threefold than that of the original CF at 1.5 VRHE. The produced new species can endow the CF‐220 with abundant acidity sites, which can enhance the adsorption toward Lewis‐basicity benzyl alcohol, confirmed by NH3‐temperature‐programmed desorption. In situ Raman result further reveals that the as‐produced CuO, Cu(OH)2, and Cu(OH)42− are the main active species toward the EBA process.

Flexible SiC nanowire/mullite fiber composite aerogel with adjustable strength based on micromechanical design

Owing to excellent high temperature resistance, high porosity and light weight, SiC aerogels possess great application prospects in thermal insulation and adsorption. However, poor mechanical properties of SiC aerogels, such as brittleness and non-bendability, hinder its application; it is still a challenge to improve and regulate the mechanical properties of SiC aerogels. Here, for the first time, we propose a micromechanical design strategy to prepare flexible SiC nanowire/mullite fiber composite aerogels (SMCAs). By optimizing the aspect ratio of the skeleton fibers to regulate the stress state of microstructures, the maximum compressive stress of that SMCAs could bear can be tuned systematically from 1.2 kPa to 1254.8 kPa, spanning 3 orders of magnitude. More importantly, thanks to its micromechanical design, SMCAs can withstand up to 80% compression deformation and up to 90° bending deformation. The present work provides a new idea for the regulation of mechanical properties of ceramic aerogels.

Growth of α and ω phase in Ti4733 detected by mechanical spectroscopy

This paper proposes a new way to detect the nucleation and growth of the ω and α phase in beta-metastable titanium alloy Ti4733. Samples were homogenized and quenched to a fully β microstructure state. Internal friction was measured by mechanical spectroscopy during heat cycles using a torsion pendulum. The first heating cycle has shown that internal friction increases during the nucleation of the ω and α phases. TEM analysis were performed in parallel to confirm the nucleation of those phases. Once the nucleation was finished (in subsequent cycles), the internal friction dropped to zero again. These maxima in internal friction related to precipitate nucleation were not reported before in such alloys. The present results show that mechanical spectroscopy could be used to better tailor the phase nucleation in β-metastable titanium alloys.