Pub Date : 2026-02-09DOI: 10.1016/j.matchar.2026.116145
Qian Wang , Meng Wang , Yufan Shen , Shuai Guo , Jiabao Guo , Xin Lin , Weidong Huang
This study resolves the atomic-layer structure of the T1p precursor and establishes the complete T1p-to-T1 transformation mechanism in Al-Li-Cu alloys. Atomic-resolution HAADF-STEM imaging reveals that T1p is a coherent five-layer modulation composed of alternating Cu-rich and Li-rich {111}Al planes formed purely by solute diffusion. Comparative analysis with the seven-layer T1 structure demonstrates that the T1p → T1 transition involves two sequential Shockley partial-dislocation slips on layers i and i-2. Thereafter, Al diffusion and layer-specific atomic rearrangement contribute to the completion of the transformation. These coupled processes convert the FCC stacking of the matrix into the HCP-like sequence of T1 and generate its final lattice configuration. The findings provide a unified atomistic framework for understanding T1 nucleation and growth in Al-Li-Cu alloys.
{"title":"Atomic-scale structure of T1p and the T1p-to-T1 transformation mechanism in Al-Li-Cu alloy","authors":"Qian Wang , Meng Wang , Yufan Shen , Shuai Guo , Jiabao Guo , Xin Lin , Weidong Huang","doi":"10.1016/j.matchar.2026.116145","DOIUrl":"10.1016/j.matchar.2026.116145","url":null,"abstract":"<div><div>This study resolves the atomic-layer structure of the T<sub>1p</sub> precursor and establishes the complete T<sub>1p</sub>-to-T<sub>1</sub> transformation mechanism in Al-Li-Cu alloys. Atomic-resolution HAADF-STEM imaging reveals that T<sub>1p</sub> is a coherent five-layer modulation composed of alternating Cu-rich and Li-rich {111}<sub>Al</sub> planes formed purely by solute diffusion. Comparative analysis with the seven-layer T<sub>1</sub> structure demonstrates that the T<sub>1p</sub> → T<sub>1</sub> transition involves two sequential Shockley partial-dislocation slips on layers <em>i</em> and <em>i-2</em>. Thereafter, Al diffusion and layer-specific atomic rearrangement contribute to the completion of the transformation. These coupled processes convert the FCC stacking of the matrix into the HCP-like sequence of T<sub>1</sub> and generate its final lattice configuration. The findings provide a unified atomistic framework for understanding T<sub>1</sub> nucleation and growth in Al-Li-Cu alloys.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"233 ","pages":"Article 116145"},"PeriodicalIF":5.5,"publicationDate":"2026-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-08DOI: 10.1016/j.matchar.2026.116141
Ji Sung Moon , Eunsoo Oh , Young Jun Jang , Eunjin Jeong , Jun Hwan Moon , Yanghee Kim , Young Keun Kim
As the complexity of integrated circuits increases, current copper (Cu) based interconnect metallization can no longer withstand the parasitic resistance-capacitance (RC) signal delay. Therefore, it is vital to develop nanoscale materials for scaled interconnects that have all three characteristics: low electrical resistivity, thermal stability, and a high potential for barrierless integration. This study explores cobalt (Co)‑platinum (Pt)-based nanowires (NWs) with a focus on their intermetallic compounds (IMCs), including Co1Pt3, Co1Pt1, and Co3Pt1. These IMCs appear attractive due to their chemical stability under thermal budget constraints. We employ the three-electrode electrodeposition and post-deposition annealing to fabricate nanoscale Co-Pt IMCs. We characterize the electrical properties of a single NW using a four-point probe in a vacuum. The measured resistivity values of the Pt-less Co3Pt1 NWs with diameters of 30 and 130 nm are 77.85 and 35.04 μΩ cm, respectively. Moreover, to emulate the dielectric environment in the back-end-of-line (BEOL) process, silica (SiO2) coating is applied to the NWs. We observe no appreciable interdiffusion of Co and Pt into silica after heat treatment at 450 °C for 6 h.
{"title":"Microstructure and resistivity of nanoscale Co-Pt intermetallic compounds for scaled interconnects","authors":"Ji Sung Moon , Eunsoo Oh , Young Jun Jang , Eunjin Jeong , Jun Hwan Moon , Yanghee Kim , Young Keun Kim","doi":"10.1016/j.matchar.2026.116141","DOIUrl":"10.1016/j.matchar.2026.116141","url":null,"abstract":"<div><div>As the complexity of integrated circuits increases, current copper (Cu) based interconnect metallization can no longer withstand the parasitic resistance-capacitance (RC) signal delay. Therefore, it is vital to develop nanoscale materials for scaled interconnects that have all three characteristics: low electrical resistivity, thermal stability, and a high potential for barrierless integration. This study explores cobalt (Co)‑platinum (Pt)-based nanowires (NWs) with a focus on their intermetallic compounds (IMCs), including Co<sub>1</sub>Pt<sub>3</sub>, Co<sub>1</sub>Pt<sub>1</sub>, and Co<sub>3</sub>Pt<sub>1</sub>. These IMCs appear attractive due to their chemical stability under thermal budget constraints. We employ the three-electrode electrodeposition and post-deposition annealing to fabricate nanoscale Co-Pt IMCs. We characterize the electrical properties of a single NW using a four-point probe in a vacuum. The measured resistivity values of the Pt-less Co<sub>3</sub>Pt<sub>1</sub> NWs with diameters of 30 and 130 nm are 77.85 and 35.04 <em>μ</em>Ω cm, respectively. Moreover, to emulate the dielectric environment in the back-end-of-line (BEOL) process, silica (SiO<sub>2</sub>) coating is applied to the NWs. We observe no appreciable interdiffusion of Co and Pt into silica after heat treatment at 450 °C for 6 h.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"233 ","pages":"Article 116141"},"PeriodicalIF":5.5,"publicationDate":"2026-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hot extrusion across the α-transus temperature (Tα) produces a strong basal texture in β-solidifying γ-TiAl alloys; however, the underlying mechanisms remain contentious owing to the disparate deformation behaviors of the constituent phases. This study employs a multi-scale characterization approach to examine the texture and microstructural evolution of a Ti-43.25Al-3.91Nb-0.98Mo-0.13B (at.%) alloy during hot extrusion across 1230–1290 °C. Microtextural decoupling via electron backscatter diffraction (EBSD) reveals that texture development follows two distinct pathways dictated by phase constitution. Below Tα, within the (α + β + γ) regime, the strong basal texture in un-recrystallized regions originates not from classical dislocation slip but from a coordinated rotation of (α/γ) lamellar colonies mediated by semi-coherent interfaces, a mechanism which, though qualitatively suggested previously, is directly validated in this work via transmission electron microscopy observations of shear strain localization at the α/γ interfaces. Above Tα, γ phase dissolution triggers a fundamental mechanistic shift: deformation becomes dominated by α-phase plastic anisotropy, and the texture is dramatically sharpened via orientation-selective continuous dynamic recrystallization (CDRX). Consequently, extrusion at 1290 °C results in superior microhardness (421.6 ± 12.1 HV), coupled with microstructural homogeneity and an exceptionally strong basal texture (7.17 m.r.d.). These findings establish a unified mechanistic framework that resolves the long-standing debate on texture correlation and provides a basis for tailoring properties in advanced TiAl alloys.
{"title":"Phase constitution-dependent deformation mechanisms and texture evolution in a β-solidifying γ-TiAl alloy during hot extrusion","authors":"Mengyu Jia, Yarong Wang, Xiaoxuan Xu, Yonghao Yu, Hongchao Kou","doi":"10.1016/j.matchar.2026.116142","DOIUrl":"10.1016/j.matchar.2026.116142","url":null,"abstract":"<div><div>Hot extrusion across the α-transus temperature (T<sub>α</sub>) produces a strong basal texture in β-solidifying γ-TiAl alloys; however, the underlying mechanisms remain contentious owing to the disparate deformation behaviors of the constituent phases. This study employs a multi-scale characterization approach to examine the texture and microstructural evolution of a Ti-43.25Al-3.91Nb-0.98Mo-0.13B (at.%) alloy during hot extrusion across 1230–1290 °C. Microtextural decoupling via electron backscatter diffraction (EBSD) reveals that texture development follows two distinct pathways dictated by phase constitution. Below T<sub>α</sub>, within the (α + β + γ) regime, the strong basal texture in un-recrystallized regions originates not from classical dislocation slip but from a coordinated rotation of (α/γ) lamellar colonies mediated by semi-coherent interfaces, a mechanism which, though qualitatively suggested previously, is directly validated in this work via transmission electron microscopy observations of shear strain localization at the α/γ interfaces. Above T<sub>α</sub>, γ phase dissolution triggers a fundamental mechanistic shift: deformation becomes dominated by α-phase plastic anisotropy, and the texture is dramatically sharpened via orientation-selective continuous dynamic recrystallization (CDRX). Consequently, extrusion at 1290 °C results in superior microhardness (421.6 ± 12.1 HV), coupled with microstructural homogeneity and an exceptionally strong basal texture (7.17 m.r.d.). These findings establish a unified mechanistic framework that resolves the long-standing debate on texture correlation and provides a basis for tailoring properties in advanced TiAl alloys.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"233 ","pages":"Article 116142"},"PeriodicalIF":5.5,"publicationDate":"2026-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-08DOI: 10.1016/j.matchar.2026.116134
Binxun Xu , Zhonghua Jiang , Chengwu Zheng , Pei Wang , Xiao Zhang , Dianzhong Li
The microstructural characteristics have a significant impact on the service performance of materials. In this study, we enhanced the mechanical properties and wear resistance of high‑carbon chromium bearing steel by designing a martensite-bainite heterogeneous microstructure and tailoring hetero-boundaries through multi-step phase transformation. This was achieved while maintaining hardness and preserving the undissolved carbide characteristics consistent with those of traditional martensite. The influence of hetero-boundaries and mechanical properties on microstructural evolution under reciprocating stress during friction was systematically investigated. The results indicated that, compared to conventional martensite or bainite microstructures, the martensite-bainite heterogeneous microstructure exhibited a superior strength-toughness balance, which mitigated rapid material loss caused by surface fracture and micro-cutting during friction. Moreover, in the sample with high-density and uniformly distributed hetero-boundaries, strain localization was alleviated, which slowed the crack propagation. In this sample, significant grain refinement was observed on the wear surface, even forming a uniform nanograin layer, which contributed to a reduced wear rate. Additionally, a high density of deformation twins formed in the subsurface layer of the wear track. These deformation twins accommodated localized strain, relieved stress concentration, and strengthened the subsurface microstructure, further reducing the wear rate. Ultimately, while maintaining hardness and undissolved carbide characteristics equivalent to those of the conventional martensite sample, the sample with the high-density and uniformly distributed hetero-boundaries exhibited a 220% improvement in impact toughness and 27% reduction in wear volume. This work extends the study of heterogeneous microstructures in the domain of friction and wear in high‑carbon chromium bearing steel, offering a new microstructural tailoring strategy for enhancing its service performance.
{"title":"Heterogeneous microstructure induced by multi-step phase transformation enhances the mechanical properties and wear resistance of bearing steels","authors":"Binxun Xu , Zhonghua Jiang , Chengwu Zheng , Pei Wang , Xiao Zhang , Dianzhong Li","doi":"10.1016/j.matchar.2026.116134","DOIUrl":"10.1016/j.matchar.2026.116134","url":null,"abstract":"<div><div>The microstructural characteristics have a significant impact on the service performance of materials. In this study, we enhanced the mechanical properties and wear resistance of high‑carbon chromium bearing steel by designing a martensite-bainite heterogeneous microstructure and tailoring hetero-boundaries through multi-step phase transformation. This was achieved while maintaining hardness and preserving the undissolved carbide characteristics consistent with those of traditional martensite. The influence of hetero-boundaries and mechanical properties on microstructural evolution under reciprocating stress during friction was systematically investigated. The results indicated that, compared to conventional martensite or bainite microstructures, the martensite-bainite heterogeneous microstructure exhibited a superior strength-toughness balance, which mitigated rapid material loss caused by surface fracture and micro-cutting during friction. Moreover, in the sample with high-density and uniformly distributed hetero-boundaries, strain localization was alleviated, which slowed the crack propagation. In this sample, significant grain refinement was observed on the wear surface, even forming a uniform nanograin layer, which contributed to a reduced wear rate. Additionally, a high density of deformation twins formed in the subsurface layer of the wear track. These deformation twins accommodated localized strain, relieved stress concentration, and strengthened the subsurface microstructure, further reducing the wear rate. Ultimately, while maintaining hardness and undissolved carbide characteristics equivalent to those of the conventional martensite sample, the sample with the high-density and uniformly distributed hetero-boundaries exhibited a 220% improvement in impact toughness and 27% reduction in wear volume. This work extends the study of heterogeneous microstructures in the domain of friction and wear in high‑carbon chromium bearing steel, offering a new microstructural tailoring strategy for enhancing its service performance.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"233 ","pages":"Article 116134"},"PeriodicalIF":5.5,"publicationDate":"2026-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-08DOI: 10.1016/j.matchar.2026.116138
Keneng Li , Zhiping Wang , Yi Shi , Jiwei Geng , Zishi Shen , Yugang Li , Dong Chen , Xianmin Chen , Haowei Wang
The corrosion behavior of Al-Zn-Mg-Cu alloys in intergranular corrosion (IGC) and exfoliation corrosion (EXCO) environments has been widely studied, but the associated corrosion-induced mechanical damage remains unclear. This study systematically investigates the relationship between dissolution, corrosion product formation, and corrosion-induced mechanical damage in IGC and EXCO solutions. Experimental observations and thermodynamic calculations show that the alloy maintains a passive state in the IGC solution, though the passivation film may rupture. Micro-galvanic corrosion at Fe-bearing phases and grain boundary precipitates leads to pitting along grain boundaries. The resulting flocculent corrosion products exhibit low hydration and limited volumetric expansion, causing only minor damage. In contrast, the EXCO solution is much more aggressive, with a corrosion rate two orders of magnitude higher than in the IGC solution. Initially, the EXCO solution etches the alloy along high-angle grain boundaries, causing significant dissolution during the first ∼12 h. With longer immersion, the alloy becomes passive again, but the ruptured passivation film offers limited protection. Meanwhile, the formation of expansive corrosion products drives layered exfoliation, which markedly reduces both strength and ductility. In comparison, the intergranular dissolution primarily degrades ductility. This work deepens the understanding of corrosion behavior and corrosion-induced mechanical damage in Al-Zn-Mg-Cu alloys under different levels of aggressiveness, paving the way for improved corrosion resistance.
{"title":"Dissolution and corrosion products induced mechanical damage in Al-Zn-Mg-Cu alloy exposed to aqueous corrosion environments","authors":"Keneng Li , Zhiping Wang , Yi Shi , Jiwei Geng , Zishi Shen , Yugang Li , Dong Chen , Xianmin Chen , Haowei Wang","doi":"10.1016/j.matchar.2026.116138","DOIUrl":"10.1016/j.matchar.2026.116138","url":null,"abstract":"<div><div>The corrosion behavior of Al-Zn-Mg-Cu alloys in intergranular corrosion (IGC) and exfoliation corrosion (EXCO) environments has been widely studied, but the associated corrosion-induced mechanical damage remains unclear. This study systematically investigates the relationship between dissolution, corrosion product formation, and corrosion-induced mechanical damage in IGC and EXCO solutions. Experimental observations and thermodynamic calculations show that the alloy maintains a passive state in the IGC solution, though the passivation film may rupture. Micro-galvanic corrosion at Fe-bearing phases and grain boundary precipitates leads to pitting along grain boundaries. The resulting flocculent corrosion products exhibit low hydration and limited volumetric expansion, causing only minor damage. In contrast, the EXCO solution is much more aggressive, with a corrosion rate two orders of magnitude higher than in the IGC solution. Initially, the EXCO solution etches the alloy along high-angle grain boundaries, causing significant dissolution during the first ∼12 h. With longer immersion, the alloy becomes passive again, but the ruptured passivation film offers limited protection. Meanwhile, the formation of expansive corrosion products drives layered exfoliation, which markedly reduces both strength and ductility. In comparison, the intergranular dissolution primarily degrades ductility. This work deepens the understanding of corrosion behavior and corrosion-induced mechanical damage in Al-Zn-Mg-Cu alloys under different levels of aggressiveness, paving the way for improved corrosion resistance.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"233 ","pages":"Article 116138"},"PeriodicalIF":5.5,"publicationDate":"2026-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-08DOI: 10.1016/j.matchar.2026.116126
Claudio de Oliveira Modesto, Mateus de Assunção Hofmann, Tiago Bender Wermuth, Sabrina Arcaro, Fabiano Raupp-Pereira, Oscar Rubem Klegues Montedo
Pyroplastic deformation, defined as the loss of dimensional stability during firing, remains a critical challenge in porcelain tile manufacturing, particularly for large-format products requiring simultaneous densification and shape retention. Conventional studies have assessed the influence of alkaline and alkaline–earth oxides by adjusting fluxing raw materials such as feldspars; however, this strategy inevitably alters SiO2 and Al2O3 contents, masking the individual contributions of fluxing oxides. Here, we introduce a novel methodological approach based on engineered ceramic frits with compositionally controlled fluxing fractions, enabling to evaluate the effect of Na2O, K2O, CaO, and MgO oxides on pyroplasticity. By using optical fleximetry, X–ray diffractometry with Rietveld refinement, microstructural analysis, and physical characterization, we systematically quantified the roles of these oxides in liquid–phase formation, viscosity, densification, and dimensional stability. Among the tested formulations, composition C4.2 (61.4 wt% clays, 2.1 wt% talc, and 36.5 wt% frit F4) exhibited the most favorable balance, combining low water absorption (0.38 ± 0.02%), moderated linear shrinkage (6.8 ± 0.1%), high flexural strength (45 ± 2 MPa), and reduced pyroplastic deformation index (7.8 ± 0.2 × 10−5 cm−1) when compared with an industrial reference (benchmark) formulation. These findings demonstrate that tailoring frit chemistry provides a mechanistic framework for resolving long–standing ambiguities regarding the isolated effect of alkaline and alkaline–earth oxides. Beyond mechanistic insight, this approach establishes a transferable design strategy that bridges oxide–level control with industrial translation, enabling the development of optimized, dimensionally stable porcelain tiles.
{"title":"Decoupling alkali and alkaline-earth oxide effects on pyroplastic deformation in porcelain tiles via engineered frits","authors":"Claudio de Oliveira Modesto, Mateus de Assunção Hofmann, Tiago Bender Wermuth, Sabrina Arcaro, Fabiano Raupp-Pereira, Oscar Rubem Klegues Montedo","doi":"10.1016/j.matchar.2026.116126","DOIUrl":"10.1016/j.matchar.2026.116126","url":null,"abstract":"<div><div>Pyroplastic deformation, defined as the loss of dimensional stability during firing, remains a critical challenge in porcelain tile manufacturing, particularly for large-format products requiring simultaneous densification and shape retention. Conventional studies have assessed the influence of alkaline and alkaline–earth oxides by adjusting fluxing raw materials such as feldspars; however, this strategy inevitably alters SiO<sub>2</sub> and Al<sub>2</sub>O<sub>3</sub> contents, masking the individual contributions of fluxing oxides. Here, we introduce a novel methodological approach based on engineered ceramic frits with compositionally controlled fluxing fractions, enabling to evaluate the effect of Na<sub>2</sub>O, K<sub>2</sub>O, CaO, and MgO oxides on pyroplasticity. By using optical fleximetry, X–ray diffractometry with Rietveld refinement, microstructural analysis, and physical characterization, we systematically quantified the roles of these oxides in liquid–phase formation, viscosity, densification, and dimensional stability. Among the tested formulations, composition C4.2 (61.4 wt% clays, 2.1 wt% talc, and 36.5 wt% frit F4) exhibited the most favorable balance, combining low water absorption (0.38 ± 0.02%), moderated linear shrinkage (6.8 ± 0.1%), high flexural strength (45 ± 2 MPa), and reduced pyroplastic deformation index (7.8 ± 0.2 × 10<sup>−5</sup> cm<sup>−1</sup>) when compared with an industrial reference (benchmark) formulation. These findings demonstrate that tailoring frit chemistry provides a mechanistic framework for resolving long–standing ambiguities regarding the isolated effect of alkaline and alkaline–earth oxides. Beyond mechanistic insight, this approach establishes a transferable design strategy that bridges oxide–level control with industrial translation, enabling the development of optimized, dimensionally stable porcelain tiles.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"233 ","pages":"Article 116126"},"PeriodicalIF":5.5,"publicationDate":"2026-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146189916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-07DOI: 10.1016/j.matchar.2026.116131
J.T. Zhang, M.H. Yang, X.J. Jiang, Q.X. Ran, J.H. Sun
To address the challenge of balancing comprehensive properties and cost in traditional alloying of laser additively manufactured titanium alloys, this study employs low-cost FeC alloy powder for alloy design and microstructure control. Using laser-directed energy deposition (LDED), different amounts of FeC alloy powder were introduced into commercial pure titanium. A systematic evaluation was conducted on the ultimate strength of Ti-Fe-C alloy systems with varying compositions under both tensile and compressive loading.The results indicate that the addition of FeC helps stabilize the metastable β phase in the alloy, leading to enhanced strength. The Fe element, characterized by a high growth restriction factor (Q), increases compositional undercooling during solidification and promotes the columnar-to-equiaxed transition. Moreover, the synergistic effect of interstitial C enables the formation of an ultrafine α/β microstructure. Notably, under tensile conditions, the FeC content should not exceed 5 wt%. The Ti-1FeC alloy exhibits an excellent tensile strength of 733 MPa along with a ductility of 15.97%. Under compression, the in-situ formed TiC phase during the DED process significantly improves the overall mechanical properties of the Ti-10FeC alloy, resulting in an ultra-high compressive strength of 2830 MPa and a ductility of 47%. This work opens a new avenue for designing low-cost, versatile, and sustainable high-performance titanium alloys.
{"title":"Synergistic control of microstructure and mechanical properties in low-cost titanium alloys via FeC alloying and laser-directed energy deposition","authors":"J.T. Zhang, M.H. Yang, X.J. Jiang, Q.X. Ran, J.H. Sun","doi":"10.1016/j.matchar.2026.116131","DOIUrl":"10.1016/j.matchar.2026.116131","url":null,"abstract":"<div><div>To address the challenge of balancing comprehensive properties and cost in traditional alloying of laser additively manufactured titanium alloys, this study employs low-cost FeC alloy powder for alloy design and microstructure control. Using laser-directed energy deposition (LDED), different amounts of FeC alloy powder were introduced into commercial pure titanium. A systematic evaluation was conducted on the ultimate strength of Ti-Fe-C alloy systems with varying compositions under both tensile and compressive loading.The results indicate that the addition of FeC helps stabilize the metastable β phase in the alloy, leading to enhanced strength. The Fe element, characterized by a high growth restriction factor (Q), increases compositional undercooling during solidification and promotes the columnar-to-equiaxed transition. Moreover, the synergistic effect of interstitial C enables the formation of an ultrafine α/β microstructure. Notably, under tensile conditions, the FeC content should not exceed 5 wt%. The Ti-1FeC alloy exhibits an excellent tensile strength of 733 MPa along with a ductility of 15.97%. Under compression, the in-situ formed TiC phase during the DED process significantly improves the overall mechanical properties of the Ti-10FeC alloy, resulting in an ultra-high compressive strength of 2830 MPa and a ductility of 47%. This work opens a new avenue for designing low-cost, versatile, and sustainable high-performance titanium alloys.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"233 ","pages":"Article 116131"},"PeriodicalIF":5.5,"publicationDate":"2026-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Al/steel dissimilar metal structures offer low density, high specific strength, and superior corrosion resistance. However, their mechanical integrity is often degraded by brittle Al-Fe intermetallic compounds (IMCs) formed at the interface. In this work, high-strength Al/steel dissimilar materials were fabricated via additive friction stir deposition (AFSD). Two distinct zones-deformation (DF) zone and deposition (DP) zone-were identified by tool features and in-situ thermal-force monitoring. It reveals that the two zones experienced distinct thermo-mechanical histories, leading to the inhomogeneity of the Al/steel materials. Higher peak temperature in the DF zone promoted the growth of a thicker, continuous Al-Fe-Si IMCs layer, whereas higher actuator force in the DP zone favored the formation of a nanoscale O/Mg-enriched amorphous layer with embedded Fe nanocrystals. These interfacial differences led to zone-dependent mechanical performance. A dual interface formation mechanism was proposed: (i) solid-state diffusion and solute enrichment under high thermal exposure driving Al-Fe-Si IMCs growth; and (ii) intense localized shear strain inducing interfacial amorphization, suppressing IMCs formation. Variations in the interfacial IMCs layer caused by different processing conditions govern the failure modes of Al/steel structures. The variations can be explained using the fitted interdiffusion coefficient model. These findings establish clear process-structure-property correlations between DF and DP zones, offering strategies for IMCs suppression and enhanced joint performance. This work provides a mechanistic basis for optimizing AFSD of dissimilar metals to produce high-performance, defect-free structural components.
{"title":"Zone-dependent thermo-mechanical history drives inhomogeneity in Al/steel dissimilar materials manufactured by additive friction stir deposition","authors":"Chunqiang Zhong , Yizhou Shen , Xunzhong Guo , Chenglong Zhao , Yuzhe Tang , Gui Wei , Haoran Guo , Wancheng Lyu , Zexing Zhou","doi":"10.1016/j.matchar.2026.116135","DOIUrl":"10.1016/j.matchar.2026.116135","url":null,"abstract":"<div><div>Al/steel dissimilar metal structures offer low density, high specific strength, and superior corrosion resistance. However, their mechanical integrity is often degraded by brittle Al-Fe intermetallic compounds (IMCs) formed at the interface. In this work, high-strength Al/steel dissimilar materials were fabricated via additive friction stir deposition (AFSD). Two distinct zones-deformation (DF) zone and deposition (DP) zone-were identified by tool features and in-situ thermal-force monitoring. It reveals that the two zones experienced distinct thermo-mechanical histories, leading to the inhomogeneity of the Al/steel materials. Higher peak temperature in the DF zone promoted the growth of a thicker, continuous Al-Fe-Si IMCs layer, whereas higher actuator force in the DP zone favored the formation of a nanoscale O/Mg-enriched amorphous layer with embedded Fe nanocrystals. These interfacial differences led to zone-dependent mechanical performance. A dual interface formation mechanism was proposed: (i) solid-state diffusion and solute enrichment under high thermal exposure driving Al-Fe-Si IMCs growth; and (ii) intense localized shear strain inducing interfacial amorphization, suppressing IMCs formation. Variations in the interfacial IMCs layer caused by different processing conditions govern the failure modes of Al/steel structures. The variations can be explained using the fitted interdiffusion coefficient model. These findings establish clear process-structure-property correlations between DF and DP zones, offering strategies for IMCs suppression and enhanced joint performance. This work provides a mechanistic basis for optimizing AFSD of dissimilar metals to produce high-performance, defect-free structural components.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"233 ","pages":"Article 116135"},"PeriodicalIF":5.5,"publicationDate":"2026-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-06DOI: 10.1016/j.matchar.2026.116128
Zhu Yan , Chao Wang , Junjie Hao , Hua Duan , Zhanjun Li , Guobiao Di , Guojin Ma , Guo Yuan
Intragranular acicular ferrite (AF) microstructure is noted for significantly enhancing the strength-toughness balance and overall mechanical properties of steel because of its tiny grain size and high misorientation grain boundary characteristics. This study systematically investigates the impact of cooling rate on the transformation kinetics and crystallographic features of AF through in-situ monitoring via high-temperature confocal laser scanning microscopy (HT-CLSM) and electron backscatter diffraction (EBSD) analysis. The findings show that a higher cooling rate significantly promotes AF growth. AF plate growth rate increases from 6.55 μm/s at 0.5 °C/s to 82.47 μm/s at 20 °C/s, while the AF transformation initiation temperature lowers as the cooling rate increases. AF variant selection is random while variant pairing shows a strong tendency. The cooling rate has a minimal influence on AF variant selection and will not change the mode of variant pairing. The development of an interlocking AF microstructure with a high density of high-angle grain boundaries (HAGBs) benefits from this predilection. The density of HAGBs grows dramatically at a cooling rate of 20 °C/s. This is explained by the bainite's strong variant selection in the multiphase structure, which is primarily controlled by the CP group mode and leads to a considerable rise in the density of block boundaries.
{"title":"Impact of cooling rate on phase transition kinetics and crystallographic characteristics of AF","authors":"Zhu Yan , Chao Wang , Junjie Hao , Hua Duan , Zhanjun Li , Guobiao Di , Guojin Ma , Guo Yuan","doi":"10.1016/j.matchar.2026.116128","DOIUrl":"10.1016/j.matchar.2026.116128","url":null,"abstract":"<div><div>Intragranular acicular ferrite (AF) microstructure is noted for significantly enhancing the strength-toughness balance and overall mechanical properties of steel because of its tiny grain size and high misorientation grain boundary characteristics. This study systematically investigates the impact of cooling rate on the transformation kinetics and crystallographic features of AF through in-situ monitoring via high-temperature confocal laser scanning microscopy (HT-CLSM) and electron backscatter diffraction (EBSD) analysis. The findings show that a higher cooling rate significantly promotes AF growth. AF plate growth rate increases from 6.55 μm/s at 0.5 °C/s to 82.47 μm/s at 20 °C/s, while the AF transformation initiation temperature lowers as the cooling rate increases. AF variant selection is random while variant pairing shows a strong tendency. The cooling rate has a minimal influence on AF variant selection and will not change the mode of variant pairing. The development of an interlocking AF microstructure with a high density of high-angle grain boundaries (HAGBs) benefits from this predilection. The density of HAGBs grows dramatically at a cooling rate of 20 °C/s. This is explained by the bainite's strong variant selection in the multiphase structure, which is primarily controlled by the CP group mode and leads to a considerable rise in the density of block boundaries.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"233 ","pages":"Article 116128"},"PeriodicalIF":5.5,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In situ electron channeling contrast imaging was applied to investigate local deformation and microstructure evolution in an electrochemically hydrogen-pre-charged type 304 austenitic stainless steel. The imaging results revealed an acceleration of γ-ε-α' martensitic transformation on the surface by hydrogen; however, no cracking was observed immediately after the transformation. A plastic deformation over 10% induced stress concentration and localized plasticity near a grain boundary, which led to hydrogen-related intergranular cracking. A side of the grain boundary acting as the cracking site was composed of α' martensite; however, the other side neighboring an intergranular crack remained austenite. Interestingly, many intergranular cracks were terminated at the α'-martensite region, which indicated that the retained austenite played a significant role in hydrogen-related intergranular cracking. The retained austenite was suggested to result in a state of high hydrogen concentration at the prior austenite grain boundary.
{"title":"Localized plasticity, transformation, and martensite cracking in hydrogen-charged metastable austenitic stainless steel studied by in situ electron channeling contrast imaging","authors":"Motomichi Koyama , Zhipeng Yang , Wenwu Xu , Eiji Akiyama","doi":"10.1016/j.matchar.2026.116127","DOIUrl":"10.1016/j.matchar.2026.116127","url":null,"abstract":"<div><div>In situ electron channeling contrast imaging was applied to investigate local deformation and microstructure evolution in an electrochemically hydrogen-pre-charged type 304 austenitic stainless steel. The imaging results revealed an acceleration of γ-ε-α' martensitic transformation on the surface by hydrogen; however, no cracking was observed immediately after the transformation. A plastic deformation over 10% induced stress concentration and localized plasticity near a grain boundary, which led to hydrogen-related intergranular cracking. A side of the grain boundary acting as the cracking site was composed of α' martensite; however, the other side neighboring an intergranular crack remained austenite. Interestingly, many intergranular cracks were terminated at the α'-martensite region, which indicated that the retained austenite played a significant role in hydrogen-related intergranular cracking. The retained austenite was suggested to result in a state of high hydrogen concentration at the prior austenite grain boundary.</div></div>","PeriodicalId":18727,"journal":{"name":"Materials Characterization","volume":"233 ","pages":"Article 116127"},"PeriodicalIF":5.5,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146190180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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