Acta Materialia最新文献

{"title":"Kinking-induced {112¯1} twin in Ti-Sn and Ti-Al alloys","authors":"Kui Rao ,&nbsp;Peiyin Liu ,&nbsp;Song Ni ,&nbsp;Min Song ,&nbsp;Ziran Liu ,&nbsp;Mingyu Gong ,&nbsp;Jian Wang","doi":"10.1016/j.actamat.2025.120737","DOIUrl":"10.1016/j.actamat.2025.120737","url":null,"abstract":"<div><div>Deformation twinning is generally operated via successive gliding of twinning dislocations/disconnections on coherent twin interface. Kinking is associated with the pileup of an array of gliding dislocations. Both twinning and kinking generate shear band and cause crystal rotation. The major difference between two mechanisms is that twinning causes a specific rotation angle while rotation angle associated with kinking is unspecific, related to the density of dislocations. In this work, we investigated shear bands in pure Ti, Ti-Sn and Ti-Al binary alloys (4 at.% Sn and 5 at.% Al) subjected to high strain rate impact. These shear bands are characterized to be {10<span><math><mrow><mover><mn>1</mn><mo>¯</mo></mover><mn>2</mn></mrow></math></span>}, {11<span><math><mrow><mover><mn>2</mn><mo>¯</mo></mover><mn>2</mn></mrow></math></span>} and {11<span><math><mrow><mover><mn>2</mn><mo>¯</mo></mover><mn>1</mn></mrow></math></span>} twins. Especially, the addition of Sn or Al significantly enhances the activation of {11<span><math><mrow><mover><mn>2</mn><mo>¯</mo></mover><mn>1</mn></mrow></math></span>} twins while inhibiting {11<span><math><mrow><mover><mn>2</mn><mo>¯</mo></mover><mn>2</mn></mrow></math></span>} twins. More importantly, the {11<span><math><mrow><mover><mn>2</mn><mo>¯</mo></mover><mn>1</mn></mrow></math></span>} twins in Ti-Sn and Ti-Al binary alloys exhibit the feature of kink bands, i.e., their boundaries are composed of basal dislocation walls and their misorientation angles are lower than the ideal twin misorientation angle. Atomic-resolution characterization reveals that these {11<span><math><mrow><mover><mn>2</mn><mo>¯</mo></mover><mn>1</mn></mrow></math></span>} twins evolve from kink bands because of the characters of dislocations at the boundary and the lower gliding resistance of basal 〈a〉 dislocations in Ti-Sn and Ti-Al binary alloys. First-principles calculations further confirm that Sn and Al promote the activation of basal 〈a〉 dislocations. Molecular statics/dynamic simulations confirm that {11<span><math><mrow><mover><mn>2</mn><mo>¯</mo></mover><mn>1</mn></mrow></math></span>} coherent twin boundary can be well reproduced by piling up and relaxing basal 〈a〉 dislocations. We thus conclude that {11<span><math><mrow><mover><mn>2</mn><mo>¯</mo></mover><mn>1</mn></mrow></math></span>} twinning can occur via kinking mechanism associated with nucleation, gliding and patterning of basal 〈a〉 dislocations.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120737"},"PeriodicalIF":8.3,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142961715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bi-addition improves the thermoelectric performance of InSb","authors":"Yixing Chen ,&nbsp;Xiao-Lei Shi ,&nbsp;Dou Li ,&nbsp;Jiaxi Zhu ,&nbsp;Meng Li ,&nbsp;Lei Zhang ,&nbsp;Zihan Zhang ,&nbsp;Zhenyu Feng ,&nbsp;Xiao Ma ,&nbsp;Hong Zhong ,&nbsp;Shuangming Li ,&nbsp;Zhi-Gang Chen","doi":"10.1016/j.actamat.2025.120736","DOIUrl":"10.1016/j.actamat.2025.120736","url":null,"abstract":"<div><div>Owing to advanced characteristics of a narrow bandgap, high electron mobility, and abundant raw material resources, InSb has been considered as a promising environmental-friendliness thermoelectric material. However, its thermoelectric performance remains unsatisfactory because of its low initial carrier concentration, low electrical conductivity, and high thermal conductivity. Here, we use Bi addition to enhance the thermoelectric performance of InSb. Bi plays two critical roles for the enhanced performance: substituting Sb and forming Bi-rich secondary phase at grain boundaries. First-principles calculations show that Bi_Sb causes the Fermi level to shift into the conduction band, which increases carrier concentration and electrical conductivity. Meanwhile, the enrichment and precipitation of Bi at grain boundaries forms heterogeneous phase boundaries, which induces an energy filtering effect to enhance the Seebeck coefficient and a high power factor of 56.1 μW cm⁻¹ K⁻² at 693 K for the InSb_0.97Bi_0.03, about 42 % higher than that of intrinsic InSb. Additionally, the formation of Bi_Sb point defects and the additional phonon scattering caused by the precipitated phase at grain boundaries result in a reduction in lattice thermal conductivity, collectively resulting in a maximum <em>ZT</em> value of 0.6 at 693 K, approximately 38 % higher than that of intrinsic InSb. Furthermore, the as-fabricated single-leg thermoelectric device based on InSb_0.97Bi_0.03 achieves an output power of 554 nW under a temperature difference of 395 K, indicating considerable application potential.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120736"},"PeriodicalIF":8.3,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142940111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Discovering the auxetic transition driven by the electronic correlation","authors":"Jintong Guan ,&nbsp;Tenglong Zhu ,&nbsp;Cong Sun ,&nbsp;Zeyan Wang ,&nbsp;Jing Weng ,&nbsp;Mingqing Liao ,&nbsp;Conglin Zhang ,&nbsp;Qingfeng Guan ,&nbsp;Erjun Kan","doi":"10.1016/j.actamat.2025.120715","DOIUrl":"10.1016/j.actamat.2025.120715","url":null,"abstract":"<div><div>The auxetic behavior in nanostructures has attracted considerable attention due to their wide potential applications. Due to the long-standing attribution of auxetic properties to the unique geometric structure of materials, the academic community's understanding of auxeticity is not profound. It is considered to have no access to tuning the auxeticity without phase transition. In this letter, an anomalous case is discovered where the auxetic transition is directly driven by the electronic correlation in Janus-Tetra-SiXY (JT-SiXY; X, <em>Y</em> = <em>O</em>, S, Se) lattice. The auxeticity is highly dependent on the electronic properties. Additionally, the auxeticity is significantly enhanced due to the Janus modification. The emerging auxetic transition effect and enhanced auxeticity would make JT-SiXY a promising candidate in two-dimensional nano-devices. Our study provides valuable clues and useful guidance for designing advanced auxetic materials.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120715"},"PeriodicalIF":8.3,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142940114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Achieving stable ultra-low elastic modulus in near-β titanium alloys through cold rolling and pre-strain","authors":"Yueyan Tian ,&nbsp;Ligang Zhang ,&nbsp;Di Wu ,&nbsp;Renhao Xue ,&nbsp;Zixuan Deng ,&nbsp;Tianlong Zhang ,&nbsp;Libin Liu","doi":"10.1016/j.actamat.2025.120726","DOIUrl":"10.1016/j.actamat.2025.120726","url":null,"abstract":"<div><div>Achieving ultra-low modulus in titanium alloys to address the stress shielding effect has been a longstanding challenge. In recent years, increasing the martensite/austenite interfaces as much as possible has emerged as a novel approach to reducing the elastic modulus of titanium. Research on Ti2448 demonstrated that inducing martensitic transformation through pre-strain to increase the interfaces can indeed achieve extremely low elastic modulus values (&lt;20 GPa); however, due to the low martensitic transformation temperature, this modulus only persists for 6 days at room temperature before reverting, which is unacceptable for long-term applications in the human body. In this study, minor cold rolling (25 % thickness reduction) and pre-strain (1.5 % tensile strain) were applied to a near-β titanium alloy Ti-26Nb-4Zr-4Sn-1Mo-1Ta (wt %) with nanoscale martensite distribution. An ultra-low elastic modulus of 31.5 GPa and moderate strength of 590 MPa were achieved in this alloy. The formation of finer and more dispersed nano martensitic domains due to cold rolling, along with further martensitic transformation induced by pre-strain, maximizes the martensite/austenite interface, and results in such ultra-low elastic modulus. The elastic modulus obtained through this method can be maintained for over one year at room temperature. Further characterization revealed that the formation of nanoscale martensite in this alloy is driven by a combination of compositional factors, internal stresses induced by rapid quenching (182.9 ± 48.4 MPa), and the inhibitory effect of the ω phase. This simple and feasible interface engineering method broadens the compositional design space for low modulus titanium alloys, providing new insights for future research on biomedical titanium alloys.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120726"},"PeriodicalIF":8.3,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nonlinear elasticity degrades monolayer fracture toughness","authors":"Israel Greenfeld ,&nbsp;Shenda Jiang ,&nbsp;Lin Yang ,&nbsp;H. Daniel Wagner","doi":"10.1016/j.actamat.2025.120727","DOIUrl":"10.1016/j.actamat.2025.120727","url":null,"abstract":"<div><div>MXenes, a novel class of monolayer transition metal carbides and nitrides, have gathered significant attention in materials science for their exceptional properties. This study focuses on investigating the influence of atomic defects on the fracture toughness of MXenes and similar monolayers. Comprehensive understanding and modeling of the fundamental physical mechanisms that govern MXene defect-mediated fracture is largely unexplored. Here, molecular dynamics simulations and theoretical fracture mechanics are employed to investigate the role of slit vacancy defects in the toughness of Ti₂C MXene. The material is found to exhibit brittle fracture behavior, and compared to classic predictions, its strength is significantly degraded by short defects. Two physical mechanisms are proposed to model MXene fracture — the material nonlinear elasticity, and the quantization of the crack driving energy. Combining both effects, this model is in excellent agreement with the MXene simulated toughness and may find application in other materials exhibiting similar toughness degradation and nonlinear elasticity.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120727"},"PeriodicalIF":8.3,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rigorous computation of short-range order unifies its controversial effects in complex concentrated alloys","authors":"Zongrui Pei ,&nbsp;Xie Zhang ,&nbsp;Markus Eisenbach ,&nbsp;Peter K. Liaw","doi":"10.1016/j.actamat.2025.120713","DOIUrl":"10.1016/j.actamat.2025.120713","url":null,"abstract":"<div><div>Direct experimental observations of chemical short-range order (SRO) in complex concentrated alloys (CCAs) have triggered high interest. However, the reported effects of SRO on yield stresses are controversial, and their atomic-scale mechanisms are elusive, which limits our ability to utilize SRO in alloy design. Here we tackle this challenge using an advanced computational approach that rigorously takes into account the critical lattice distortion in CCAs and further verify our theoretical predictions with experiments. We show that the CoCrNi model alloy has a narrow temperature window around 670 °C for SRO formation. This explains why the mechanical effect of SRO is observed in some experiments but not in others. We propose an effective alloy-doping method to control SRO and reveal atomic-bonding types that dominate SRO formation for different alloys. The strategies and insights generally apply to a broad spectrum of alloys, laying the foundation for designing advanced alloys by manipulating their SRO.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120713"},"PeriodicalIF":8.3,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142940112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Setting material benchmarks at large-strain limits via ultimate strengths","authors":"Xinxin Gao ,&nbsp;Kan Zhang ,&nbsp;Qiang Zhu ,&nbsp;Changfeng Chen ,&nbsp;Chang Liu","doi":"10.1016/j.actamat.2025.120724","DOIUrl":"10.1016/j.actamat.2025.120724","url":null,"abstract":"<div><div>Structural stability and durability are two foundational attributes underpinning all material functionalities, yet traditional approach only sets stability criteria in terms of elastic parameters derived at small strains, then extends their use to probing strength and durability at large strains via empirical relations due to a lack of accurate material benchmarks at strong deformation. Such extrapolations, however, may cause major quantitative or even qualitative deviations in assessing material behaviors at large strains when the elastic parameters fail to capture distinct underlying physics under strong deformations. Here, we introduce ultimate strengths, defined by peak stresses on diverse deformation paths from first-principles calculations, to set accurate and robust benchmarks for assessing materials at large-strain limits. We take transition-metal diborides as an exemplary class of materials to showcase strong directional anisotropy and load dependence of stress responses at large strains, in sharp contrast to the behaviors predicted by elastic parameters. We elucidate the impact and mechanism of load-constrained deformation, bond charge distribution, and electronic band structure on mechanical responses at elastic or dynamic stability limits. This work fulfills a longstanding need in materials science to set robust and accurate benchmarks that are tailored as explicit descriptors for key material characteristics under strong deformations.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120724"},"PeriodicalIF":8.3,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937006","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Anisotropic structure in a vapor-deposited Pd-based metallic glass","authors":"Peihao Sun ,&nbsp;Alessandro Martinelli ,&nbsp;Jacopo Baglioni ,&nbsp;Francesco Dallari ,&nbsp;Marco Di Michiel ,&nbsp;Alexey P. Melnikov ,&nbsp;Konrad Samwer ,&nbsp;J.B. Hastings ,&nbsp;Giulio Monaco","doi":"10.1016/j.actamat.2025.120711","DOIUrl":"10.1016/j.actamat.2025.120711","url":null,"abstract":"<div><div>The understanding of the structure of amorphous solids beyond nearest-neighbors has long been sought after. While recent works have demonstrated evidence for medium-range ordering and its importance for the physical properties of glassy systems, few have investigated mesoscopic structural correlations beyond a few nanometers. In this work, combining X-ray nano-diffraction with high-energy X-ray total scattering with a small focus, we have not only found structural anisotropy in a vapor-deposited Pd_77.5Cu₆Si_16.5 metallic glass sample which appears to show two distinct and well-defined structures in different directions, but also obtained detailed characterizations of this anisotropic structure in real space. Upon annealing, the sample loses the long-range anisotropy, and at the same time, it appears to densify with a contraction of higher-order coordination shells. In light of recent works, our results may indicate a transition between two structures in the sample with different densities, medium-range ordering, and degrees of anisotropy. We expect these results to be relevant to a larger family of metallic glass systems, where similar discoveries may be made with the use of high-quality, small-focus X-ray beams.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120711"},"PeriodicalIF":8.3,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phase-field study of precipitate morphology in epitaxial high-entropy oxide films","authors":"Yueze Tan ,&nbsp;Jacob T. Sivak ,&nbsp;Saeed S.I. Almishal ,&nbsp;Jon-Paul Maria ,&nbsp;Susan B. Sinnott ,&nbsp;Yanzhou Ji ,&nbsp;Long-Qing Chen","doi":"10.1016/j.actamat.2025.120721","DOIUrl":"10.1016/j.actamat.2025.120721","url":null,"abstract":"<div><div>High-entropy oxides (HEOs) with multiple equal-molar cations may exist as single-phase solid solutions at sufficiently high temperatures. However, such solid solutions are susceptible to the formation of stable or metastable precipitates at lower temperatures. The morphology of such precipitates could have profound influence on the resulting properties. Here, we extended our recently developed phase-field model of simultaneous solid solution and stoichiometric phases for binary alloy systems to multicomponent oxides. Using the stress-free lattice parameters and elastic constants of precipitate phases as well as the interfacial energy between the precipitate and the solid solution matrix from density-functional theory calculations, we performed phase-field simulations to understand the morphology of coherent CuO-rich precipitates in epitaxial Mg_0.2Co_0.2Ni_0.2Cu_0.2Zn_0.2O thin films validated by transmission electron microscopy (TEM) observations. By analyzing the detailed precipitate sizes, orientation, and spatial distributions as well as the stress and strain distributions along different cross-sections, we reveal the important impact of elastic constraints on the CuO precipitate distributions in thin films. These findings can provide useful insights into controlling the coherent precipitate morphology in epitaxial HEO thin films.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120721"},"PeriodicalIF":8.3,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deformation behavior of nanoporous gold nanoparticles during compression","authors":"Ben Engelman ,&nbsp;Santhosh Mathesan ,&nbsp;Tatyana Fedyaeva ,&nbsp;Anuj Bisht ,&nbsp;Eugen Rabkin ,&nbsp;Dan Mordehai","doi":"10.1016/j.actamat.2025.120723","DOIUrl":"10.1016/j.actamat.2025.120723","url":null,"abstract":"<div><div>In this experimental-computational study, we propose a novel method to study the inhomogeneous deformation of nanoporous Au structures and quantifying locally their deformation. By combining the dewetting method and dealloying of Ag-Au alloys, we fabricated sub-micrometer scale hemispherical nanoporous Au nanoparticles (NPG-NPs). The formed nanoparticles have an average ligament diameter of 13 nm and diameter ranging between 200 and 800 nm. A few grain boundaries, mostly of twin type, were found within the NPG-NPs. Under compression with a flat diamond punch, the load-displacement curves exhibited linear increase, up to a certain compression depth, above which a significant rise in the slope was identified. Molecular dynamics (MD) simulations of NPG-NPs with various sizes, porosities, and ligament diameters were conducted. The simulated load-displacement curves closely matched the experimental ones. With the help of the MD simulations, we identified the dependencies of the NPG-NP mechanical properties on their geometry. To better understand how to quantify these dependencies, we analyzed the densification profiles during the deformation. We found that the densification is inhomogeneous and localized beneath the compressing punch. In combination with the dislocation density profiles, we correlated the densification region with the mean-free path of dislocations and their depletion due to the high surface-to-volume ratio. We showed that the slope increase in the load-displacement curves is attributed to the interaction between the densified region (dislocation structure) and the substrate. Finally, we propose a model for the inhomogeneous deformation, enabling to determine the contact stresses in the experiments.</div></div>","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":"286 ","pages":"Article 120723"},"PeriodicalIF":8.3,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142936518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}