Materials Science and Engineering: A最新文献

{"title":"Exploring room-temperature deformation mechanisms of a B2-strengthened refractory compositionally complex alloy","authors":"Aparajita Pramanik ,&nbsp;Chethan Konkati ,&nbsp;Stephan Laube ,&nbsp;Liu Yang ,&nbsp;Sandipan Sen ,&nbsp;Alexander Kauffmann ,&nbsp;Martin Heilmaier ,&nbsp;Ankur Chauhan","doi":"10.1016/j.msea.2025.148180","DOIUrl":"10.1016/j.msea.2025.148180","url":null,"abstract":"<div><div>The room-temperature deformation mechanisms in a B2-precipitation-strengthened 27.3Ta–27.3Mo–27.3Ti–8Cr–10Al (at.%) body-centered cubic (BCC) refractory compositionally complex alloy (RCCA) was examined using nanoindentation under two aging conditions. Aging at 900 °C for 1 h resulted in nearly spherical B2 precipitates with an average diameter of (5 ± 1) nm. Prolonged aging for 1000 h resulted in coarsened, elongated precipitates aligned along three orthogonal &lt;001&gt; directions, averaging (80 ± 16) nm in length, (26 ± 4) nm in width, and a volume fraction of 0.25 ± 0.05. The precipitates maintained a coherent interface with the matrix under both aging conditions. After 1000 h of aging, a small lattice parameter mismatch of + (0.6 ± 0.4) % was estimated, demonstrating good microstructural stability. Deformation at room temperature involved cooperative shearing of B2 precipitates by paired a/2⟨111⟩ dislocations, with an antiphase boundary energy of (150 ± 39) mJ/m². The dislocation-precipitate interaction evolved from weakly to strongly coupled pairwise cutting between the 1 h and 1000 h aged samples, leading to an approximately 6–12 % hardness reduction. The estimated critical radius and precipitation strengthening contribution further validate this transition, showing reasonable agreement with TEM observations. No Orowan looping, twinning, or phase transformation was observed.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"931 ","pages":"Article 148180"},"PeriodicalIF":6.1,"publicationDate":"2025-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143632196","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}

{"title":"Characterization of the milling-induced hardness gradient in the near-surface material volume of high manganese TWIP steel 1.7401 by nanoindentation","authors":"S. Wolke,&nbsp;M. Smaga,&nbsp;T. Beck","doi":"10.1016/j.msea.2025.148183","DOIUrl":"10.1016/j.msea.2025.148183","url":null,"abstract":"<div><div>The hardness gradient induced by up and down milling in the near-surface material volume of high-manganese TWIP steel 1.7401 was characterised up to a surface distance of 50 μm using nanoindentation. Hereby, even the influence of various small indentation depths was such pronounced that the indentation size effect influenced the measured hardness significantly and was, hence, studied. In a first step, the effect of uniaxial, quasi-static deformation on hardness was investigated, which serves as a comparison to hardening by milling which is associated with a complex, multiaxial deformation. Subsequently, suitable parameters for characterization of the milling induced hardness gradient were identified through variation of indentation depths and indentation depth-to-indent spacing ratios. Additionally, the near-surface hardness gradient was examined transversely and longitudinally to the feed direction to analyse whether possible process-induced differences occur due to intermittent cutting. Furthermore, the hardness in the nanocrystalline layer was examined in detail and correlated with the respective microstructures, observed through FIB cutting and ion beam imaging. Finally, the hardness gradients after up and down milling were compared, the effect of electrolytic polishing on the near surface hardness gradient was analysed and the hardness in the rolling skin, representing the initial state, was studied. Milling results in a maximum increase in hardness of approximately 50 % in comparison with the base material, and the hardness decreases degressively with increasing distance to the surface up to a depth of approximately 20 μm. Hardness increases in the milling-induced near-surface material which can be attributed to higher dislocation density. The near-surface layer, measuring 1–2 μm in depth, consists of fine-grained material, and the transition to coarser grains corresponds with a change in hardness slope. No significant hardness gradient was detected along the feed direction, and up and down milling results in similar hardness gradients.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"931 ","pages":"Article 148183"},"PeriodicalIF":6.1,"publicationDate":"2025-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143628161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Achieving superior strength and plasticity in cold metal transfer plus pulse wire arc additive manufacturing of a novel Al-Si-Mg-Cu-Zn alloy via in-situ laser remelting","authors":"Meng Cao ,&nbsp;Shuncun Luo ,&nbsp;Xianwei Jiang ,&nbsp;Xiaonan Wang ,&nbsp;Hiromi Nagaumi ,&nbsp;Zengrong Hu","doi":"10.1016/j.msea.2025.148165","DOIUrl":"10.1016/j.msea.2025.148165","url":null,"abstract":"<div><div>Al-Si-Mg alloys are widely used in aerospace and automotive industries due to their excellent casting properties and wear resistance. However, a key challenge in wire arc additive manufacturing of Al-Si-Mg alloys is the presence of metallurgical defects and inferior mechanical properties, areas that have received limited attention in existing research. Critical factors impacting performance include the porosity in deposited layers and the formation of columnar grains caused by high energy input. This study explores the application of interlayer laser remelting to a novel Al-Si-Mg-Cu-Zn alloy produced via the Cold Metal Transfer plus Pulse (CMT-P) process and provides a comprehensive analysis of their microstructure, mechanical properties, and strengthening mechanisms. The findings reveal that interlayer laser remelting significantly reduces porosity, suppresses the growth of columnar grains, and promotes the formation of equiaxed grain zones with a higher density of low-angle grain boundaries. Furthermore, the laser-affected zone generated during remelting results in finer and denser precipitates, thereby effectively enhancing the mechanical properties. Notably, the CMT-P+2.2 kW laser-remelted samples demonstrate an average ultimate tensile strength of 373.48 ± 0.51 MPa, yield strength of 267.33 ± 9.61 MPa, and an elongation of 11.3 ± 0.5 %, reflecting improvements of 29.24 %, 42.6 %, and 11.5 %, respectively, compared to the CMT-P samples. The study also analyzed the effects of four strengthening mechanisms during the laser remelting process, identifying precipitation strengthening and solid solution strengthening as the most significant contributors to the enhanced performance of the Al-Si-Mg-Cu-Zn alloy. This research presents an innovative and feasible approach for fabricating Al-Si-Mg-Cu-Zn alloys with excellent mechanical properties through additive manufacturing.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"930 ","pages":"Article 148165"},"PeriodicalIF":6.1,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143601565","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}

{"title":"Crystal plasticity analysis of instrumented indentation on a service-aged Cr–Mo steel","authors":"Zhe Lyu,&nbsp;Leijun Li","doi":"10.1016/j.msea.2025.148118","DOIUrl":"10.1016/j.msea.2025.148118","url":null,"abstract":"<div><div>Samples extracted from pressure vessels that had been in service for 40 years at 480 °C revealed a 37% increase in tensile strength and a 24% decrease in elongation compared with new material. However, artificially aging at 700 °C for 2 h revealed a decrease in tensile strength and a slight decrease in elongation despite having a similar Holloman–Jaffe (HJ) tempering parameter to the service-exposed samples. Mesoscale crystal plasticity simulations were conducted to understand the aging microstructure on microhardness indentation, incorporating a dislocation density-based constitutive law. Experimental results in dislocation density, grain orientations, and particle sizes were used as inputs for the crystal plasticity model. Atomic force microscopy (AFM) was used to measure the depth profile of the nanoindentation marks, validating the model. Both experimental and simulation results indicated that precipitation hardening by nanoscale semi-coherent Mo₂C significantly strengthened the ferrite matrix during aging. The dissolution of Fe₃C in pearlite had decreased the tensile strength, while the increased carbide precipitation and dislocation densities had increased the tensile strength of the ferrite matrix in the service-exposed samples. An indentation model for microhardness of the pearlite regions confirmed that the spheroidization of carbides in pearlite during artificial aging had contributed to the decrease in hardness and strength.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"930 ","pages":"Article 148118"},"PeriodicalIF":6.1,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143601563","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"ConvFeatNet ensemble: Integrating microstructure and pre-defined features for enhanced prediction of porous material properties","authors":"Yuhai Li ,&nbsp;Tianmu Li ,&nbsp;Longwen Tang ,&nbsp;Shiyu Ma ,&nbsp;Qinglin Wu ,&nbsp;Puneet Gupta ,&nbsp;Mathieu Bauchy","doi":"10.1016/j.msea.2025.148173","DOIUrl":"10.1016/j.msea.2025.148173","url":null,"abstract":"<div><div>This study introduces ConvFeatNet, a deep learning framework specifically designed to predict the mechanical properties of porous materials based on their microstructures. Despite dataset limitations, ConvFeatNet integrates both structural and predefined features with deep learning techniques to enhance predictive accuracy. The ensemble version of ConvFeatNet achieves a mean absolute error (MAE) of <strong>0.85 J/m²</strong> in predicting fracture energy using 1000 samples, outperforming a simple MLP (MAE: <strong>1.08 J/m²</strong>) and CNN (MAE: <strong>1.38</strong> J/m²) by <strong>21 %</strong> and <strong>38 %</strong>, respectively. Expanding the dataset to 10,000 samples further reduces the MAE to <strong>0.51 J/m²</strong>, representing a <strong>24 %</strong> improvement over the MLP and a <strong>9 %</strong> improvement over the CNN. Additionally, SHAP analysis is employed to interpret model predictions, revealing the key structural determinants influencing mechanical behavior. This study highlights the synergy between deep learning and domain knowledge, offering a robust approach for deciphering the mechanical properties of porous materials.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"931 ","pages":"Article 148173"},"PeriodicalIF":6.1,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143620069","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}

{"title":"Unveiling the strength-plasticity synergy in Ti-doped CoCrFeNi2-based high-entropy alloys with precipitate phase heterostructures","authors":"Zhenyu Wu ,&nbsp;Zhiqin Wen ,&nbsp;Li Tang ,&nbsp;Taoyi Lu ,&nbsp;Qiucai Luo ,&nbsp;Xinhuan Ban ,&nbsp;Yuhong Zhao","doi":"10.1016/j.msea.2025.148178","DOIUrl":"10.1016/j.msea.2025.148178","url":null,"abstract":"<div><div>Face-centered cubic (FCC) high-entropy alloys (HEAs) are constrained by their relatively low yield strengths, while heterostructures have emerged as a cutting-edge topic offering a promising method to solve the strength-plasticity trade-off dilemma. In this work, the multi-phase heterogeneous structure CoCrFeNi₂Ti_<em>x</em> HEAs (<em>x</em> = 0, 0.4, 0.8 and 1.2) is developed by adding large atomic radii Ti into CoCrFeNi₂ matrix to improve the mechanical properties. With the addition of Ti, the alloys transform from a single solid solution to a multi-phase heterogeneous structure, and Ti0.8 exhibits a precipitated phase heterostructure consisting of a soft FCC phase and a hard <em>ƞ</em>-Ni₃Ti + <em>σ</em> phase. Phase components of CoCrFeNi₂Ti_<em>x</em> are also proved by phase formation theory and phase diagram calculations (CALPHAD). It is noteworthy that the increase in Ti content results in a substantial improvement of the strength, and Ti0.8 HEAs shows the optimal balance of strength and plasticity with a compressive yield strength of 1177 MPa and a compressive strain of 24.4 %. The non-uniformity between the soft phase and the hard phase leads to high back stresses in the FCC grains and high forward stresses in the <em>ƞ</em>-Ni₃Ti+<em>σ</em> grains, which triggers a composite heterogeneous deformation-induced (HDI) strengthening, which allows the alloys to increase the strength without compromising its plasticity. The fracture mechanism of Ti0.8 HEAs is mainly a mixture of shear and disintegration-based fracture mode and accompanied by tough nests. In addition, dislocation strengthening and precipitation strengthening play a dominant role in the strengthening of CoCrFeNi₂Ti_<em>x</em> HEAs. The above phenomena are further confirmed by the fracture mechanism and strengthening mechanism. The present work provides new insights for further development of high-performance HEAs, paving the way for tailored microstructures with exceptional properties.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"930 ","pages":"Article 148178"},"PeriodicalIF":6.1,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143601564","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}

{"title":"Correlation of TRIP effect and Lüders band in a 2.3 GPa ultra-high yield strength medium Mn steel with martensite matrix","authors":"Yi Liu ,&nbsp;Jiale Jiang ,&nbsp;Yunjie Li ,&nbsp;Jian Kang ,&nbsp;Xiaolin Li ,&nbsp;Guo Yuan ,&nbsp;Guodong Wang","doi":"10.1016/j.msea.2025.148172","DOIUrl":"10.1016/j.msea.2025.148172","url":null,"abstract":"<div><div>Enhancing the ductility of ultra-high-yield-strength steel materials exceeding 2 GPa presents a significant challenge due to the intrinsic trade-off between strength and ductility. Strain-aging processes have shown potential to increase yield strength while mitigating the exhaustion of work hardening, facilitating the combination of ultra-high yield strength and exceptional ductility in Transformation-Induced Plasticity (TRIP)-assisted steels. However, the underlying mechanisms of Lüders band formation and its quantitative relationship with the TRIP effect in steels with a yield strength above 2 GPa remain to be fully elucidated. In this study, we prepared an easily formable initial medium Mn steel with martensite/austenite microstructure through low-cost composition design and a simplified process (hot rolling + tempering). The strain aging process endows this steel with a yield strength as high as 2294 MPa and a uniform elongation exceeding 10 %. The results demonstrate that with the increase in pre-strain, some block austenite gradually transforms into fresh martensite and high-density of dislocation can be obtained, which leads to a very high bake hardening response of 531–569 MPa, making significant contributions to the enhancement of yield strength. The strain mechanism of Lüders band is analyzed by digital image correlation method (DIC). When the pre-strain increases from 3 % to 4 %, the strain value of Lüders band increase, and the austenite fraction in the strain interval of Lüders zone changes little, which indicates that there is little TRIP effect in Lüders band deformation. At the same time, a large amount of austenite performs TRIP effect in the hardening stage after Lüders band deformation, which provides enough work hardening and obtains a very high uniform elongation of about 10 % at 2.3 GPa. The main mechanism in Lüders zone strain is dislocation slip, accompanied by dislocation multiplication behavior.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"930 ","pages":"Article 148172"},"PeriodicalIF":6.1,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143609474","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}

{"title":"Low-cost secondary hardening steel under double ageing: Dual-precipitation control, austenite modification and strength-toughness improvement","authors":"Haofei Zhu ,&nbsp;Zhiping Xiong ,&nbsp;Jianwen Mao ,&nbsp;Xingwang Cheng","doi":"10.1016/j.msea.2025.148159","DOIUrl":"10.1016/j.msea.2025.148159","url":null,"abstract":"<div><div>Reducing cobalt content in secondary hardening ultra-high strength steels (UHSSs) is eager for cost reduction, but meanwhile the M₂C precipitation decreases resulting in a decrease in strength. Adding aluminum to induce NiAl precipitation can increase the strength but the toughness is reduced. Therefore, it remains a challenge to keep decent toughness through NiAl and M₂C dual precipitation when reducing Co content. Here, double ageing is proposed in a low-cost UHSSs to achieve good combination of strength and toughness through dual-precipitation control and austenite modification. Ageing at 482 °C for 32 h followed by ageing at 600 °C for 20 min (DA482 + 600) exhibits a smaller size of M₂C carbide and a smaller number density of NiAl particle than that ageing at 600 °C for 20 min followed by ageing at 482 °C for 32 h (DA600 + 482). Additionally, the DA482 + 600 sample obtains a larger volume fraction of film reversed austenite and a smaller size of blocky reversed austenite. These make it have higher impact toughness. Although the precipitation strengthening for NiAl particles and M₂C carbides is different in two samples, when considering the interaction during dislocation movement through these precipitates, Pythagorean addition rule indicates that the total precipitation strengthening is similar. Additionally, the course of heat treatment is the same and, in turn, the solid solution, dislocation density and width of martensitic laths are comparable, leading to similar strengthening contributions. As a result, the yield strength remains comparable high. When comparing strength-toughness and raw materials cost with representative secondary hardening UHSSs, the DA482 + 600 sample exhibits superior combination.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"931 ","pages":"Article 148159"},"PeriodicalIF":6.1,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143628164","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}

{"title":"Unique discontinuous yielding mechanism of fine-grained metastable β-type Ti-Nb-Mo alloy","authors":"Bingjie Zhang ,&nbsp;Shewei Xin ,&nbsp;Mingda Huang ,&nbsp;Jingzhe Niu ,&nbsp;Qian Li ,&nbsp;Yan Zhang ,&nbsp;Xi Pan ,&nbsp;Xingwu Li ,&nbsp;Jun Cheng ,&nbsp;Wenqi Mao ,&nbsp;Tianlong Zhang ,&nbsp;Nobuhiro Tsuji","doi":"10.1016/j.msea.2025.148168","DOIUrl":"10.1016/j.msea.2025.148168","url":null,"abstract":"<div><div>The fundamental mechanisms of discontinuous yielding in a ternary Ti-Nb-Mo alloy with a fine-grained microstructure were investigated using the in-situ synchrotron radiation X-ray technique. The findings indicate that although the martensitic transformation initiated at the elastic deformation stage and progressed with the propagation of the Lüders-like deformation, the rapid large-scale dislocation multiplication within the β-matrix was the underlying cause of the discontinuous yielding phenomenon. Furthermore, the presence of high-density dislocations facilitated martensitic transformation within the Lüders band, which allowed the martensitic transformation to persist even after the front of the Lüders band passed, resulting in an unconventional propagation behavior of the Lüders band. This unique deformation mechanism enables the alloy to rapidly regenerate work hardening after the yield drop, leading to a markedly increase in uniform elongation of the present alloy. This study provides new information on the discontinuous yielding of the metastable Ti-based alloys.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"930 ","pages":"Article 148168"},"PeriodicalIF":6.1,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143609475","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}

{"title":"Microstructure and very high cycle fatigue characteristics of powder bed fused – laser beam (PBF-LB) scandium-free Al-Mg-Zr alloy","authors":"Shawkat I. Shakil ,&nbsp;Wiktor Bednarczyk ,&nbsp;Marta Gajewska ,&nbsp;Zaynab Mahbooba ,&nbsp;Ankit Saharan ,&nbsp;Andrea Tridello ,&nbsp;Davide S. Paolino ,&nbsp;Meysam Haghshenas","doi":"10.1016/j.msea.2025.148177","DOIUrl":"10.1016/j.msea.2025.148177","url":null,"abstract":"<div><div>This study investigates the microstructure and very high cycle fatigue (VHCF) behavior of a powder bed fusion–laser beam (PBF-LB) processed scandium-free Al-Mg-Zr alloy (commercially known as EOS Al5X1) through advanced microstructural characterization, defect analysis, ultrasonic fatigue testing, and detailed fractographic examination. The analysis focuses on defect-driven crack initiation, particularly process-induced volumetric defects such as pores, lack of fusion, and non-metallic (oxide) inclusions. Scanning electron microscopy-based fractography reveals that in the VHCF regime, where the number of cycles to failure (N_f) &gt; 10⁷ cycles, fatigue crack initiation predominantly shifts toward the subsurface or interior of the specimen. In multiple cases, process-induced volumetric defects facilitated crack initiation, resulting in characteristic 'fisheye' fracture morphologies. The chemical composition of these critical defects was also analyzed in detail. The study highlights the significant impact of process-induced volumetric defects on fracture morphology and examines the influence of defect size and location on VHCF performance. These findings provide deeper insight into the interplay between processing defects and crack nucleation, underscoring the necessity of advanced defect characterization to better understand VHCF life variability.</div></div>","PeriodicalId":385,"journal":{"name":"Materials Science and Engineering: A","volume":"930 ","pages":"Article 148177"},"PeriodicalIF":6.1,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143579406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}