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Item type:Publication, Access status: with files , Strengthening mechanism in Al–Cu–Li alloy processed by friction consolidation followed by high-pressure torsion(Elsevier, 2026-01-15); ; ; ; The primary objective of this study is to explore the precipitation behavior of Al–Cu–Li alloy powder processed through a two-step approach: friction consolidation (FC) followed by high-pressure torsion (HPT). Microstructure analysis by scanning electron microscope shows a refined microstructure after FC, with a further reduction in grain size following HPT. X-ray diffraction analysis confirmed the formation of T1, T2, and 𝛿 precipitates after FC, which persisted even after HPT. Small-angle X-ray scattering shows a reduction in the volume fraction of larger precipitate particles after HPT, while the smaller grain volume fraction increased. Additionally, the volume fraction of precipitates decreased as a function of strain. To understand the contributions of various mechanisms to an enhanced hardness observed after HPT, a physical model was employed. This study explores how HPT influences dislocation behavior, precipitation, and grain size, highlighting its role in tailoring the microstructure and properties of the friction consolidated Al–Cu–Li alloy.Publicationtype: Journal Article58 13 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Strain hardening behavior of additively manufactured and annealed AlSi3.5Mg2.5 alloyThe ductility of the Al alloys produced by additive manufacturing (AM) has become a critical property, as the AM Al alloys are increasingly used in the automotive industry. However, the ductility of as-built AM Al alloys is relatively low, even with optimized AM conditions. The post-annealing treatment provides an efficient way to improve ductility. Previous investigation has shown that the annealed AM AlSi3.5Mg2.5 alloy possesses superior ductility. However, the plastic deformation micro-mechanisms of the annealed AM AlSi3.5Mg2.5 alloy remain unclear. In this study, in-situ neutron diffraction was employed to explore the annealed AM AlSi3.5Mg2.5 alloy. The evolutions of phase stresses, dislocation density, and crystallite size in the annealed AM AlSi3.5Mg2.5 alloy during tensile deformation were analyzed. The experimental investigation reveals that the dislocation density in the Al matrix of the annealed AM AlSi3.5Mg2.5 alloy increases slowly in the early plastic deformation stage, and it reaches a saturated level upon the following uniform deformation. The crystallite size decreases quickly in the early deformation stage, and then it decreases slowly. The Kocks-Mecking model and the Voce model can capture the strain hardening behavior well. The determined physical constitutive equations can be applied in continuum mechanical computer simulations.Publicationtype: Journal ArticleScopus© Citations 8 100 520 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Paraelectric KH₂PO₄ nanocrystals in monolithic mesoporous silica: Structure and lattice dynamicsCombining dielectric crystals with mesoporous solids allows a versatile design of functional nanomaterials, where the porous host provides a mechanical rigid scaffold structure and the molecular filling adds the functionalization. Here, we report a study of the complex lattice dynamics of a SiO₂:KH₂PO₄ nanocomposite consisting of a monolithic, mesoporous silica glass host with KH₂PO₄ nanocrystals embedded in its tubular channels ~12 nm across. A micro-Raman investigation performed in the spectral range of 70–1600 cm−1 reveals the complex lattice dynamics of the confined crystals. Their Raman spectrum resembles the one taken from bulk KH₂PO₄ crystals and thus, along with X-ray diffraction experiments, corroborates the successful solution-based synthesis of KH₂PO₄ nanocrystals with a structure analogous to the bulk material. We succeeded in observing not only the high-frequency internal modes (~900–1200 cm−1), typical of internal vibrations of the PO₄ tetrahedra, but, more importantly, also the lowest frequency modes typical of bulk KH₂PO₄ crystals. The experimental Raman spectrum was interpreted with a group theory analysis and first-principle lattice dynamics calculations. The calculated phonon spectrum reveals a lattice instability against two optical modes probably related to an intrinsic anharmonicity of the vibrational dynamics of KH₂PO₄ crystals originating from the uncertainty of proton localization within the network of hydrogen bonds. The analysis of calculated eigen-vectors indicates the involvement of hydrogen atoms in most phonon modes corroborating the substantial significance of the hydrogen subsystem in the lattice dynamics of paraelectric bulk and of KH₂PO₄ crystals in extreme spatial confinement. A marginal redistribution of relative Raman intensities of the confined compared to unconfined crystals presumably originates in slightly changed crystal fields and interatomic interactions, in particular for the parts of the nanocrystals in close proximity to the silica pore surfaces.Publicationtype: Journal Article60 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Fragmentation and refinement behavior and underlying thermodynamic mechanism of WC reinforcement during selective laser melting of Ni-based compositesThe WC-reinforced Inconel 718 composites were successfully fabricated through selective laser melting (SLM) additive manufacturing technology. Influences of the applied laser energy densities on the thermodynamics within the molten pool, fragmentation behavior of WC particles, and underlying fragmentation mechanism were investigated through experiments and simulations. The results revealed that the fragmentation behavior of WC particles was greatly dependent on the applied laser energy input. As a relatively low laser energy density was applied, the alloyed reaction layer formed around WC particles, and then experienced a fragmentation into a certain number of carbides in the vicinity of WC particles, due to the temperature gradient and resultant thermal tensile stress exerted at the interface of WC particles and molten Inconel 718 alloy. This fragmentation of WC particle was defined as the dissolution-diffusion-fragmentation mechanism. For an elevated laser energy density of 330 J/m was used, an increased temperature gradient and attendant thermal stress formed, and the initially incorporated WC particles experienced a severe heat damage, thereby directly fragmenting the WC particles into the refined pieces. Meanwhile, the molten liquid with more intense thermal convections favored the homogeneous distribution of the broken WC particles and the formation of the alloyed reaction layer between WC particles and molten Inconel 718 alloy liquid, which was predominated by the fragmentation-dissolution-diffusion mechanism.Publicationtype: Journal Article32