Article
Mechanics
Stephen Daynes, Joseph Lifton, Wen Feng Lu, Jun Wei, Stefanie Feih
Summary: Metallic lattice structures are known for their high specific elastic moduli and strength, but their resistance to fracture is not well understood. In this study, Ti-6Al-4V lattice structures were additively manufactured using selective laser melting, and their fracture toughness characteristics were investigated under Mode-I loading. The results showed that toughness increases with relative density in a power law manner, and a new functional grading optimisation methodology was introduced to increase fracture toughness. After size optimisation, initiation fracture toughness was improved by up to 37%.
EUROPEAN JOURNAL OF MECHANICS A-SOLIDS
(2021)
Article
Engineering, Mechanical
A. Diaz, J. M. Alegre, I. I. Cuesta, E. Martinez-Paneda, Z. Zhang
Summary: This study numerically investigates the influence of mechanical properties on the notch fracture resistance of Ti-6Al-4V produced by Selective Laser Melting. The results show that heat treatment and hot isostatic pressing enhance the ductility of the material, while the presence of oxygen uptake in non-inert atmospheres leads to brittle fracture.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2022)
Article
Chemistry, Physical
Yujian Wang, Junjie Li, Jianwei Li, Lei Zhang, Jiankai Ma, Zhijun Wang, Feng He, Jincheng Wang
Summary: Coarsening of the basketweave alpha + beta microstructure in Ti-6Al-4V during thermal cycling is driven by multiple dissolution and precipitation transformations instead of conventional Ostwald ripening. This study reveals that the vanishing of alpha plates continues during repeated thermal cycling through two mechanisms, which are related to the Gibbs-Thomson effect. The influence of cycling frequency and total duration on the coarsening transformation is also detected. Long cycling duration leads to severe coarsening, while the final coarsening of alpha plates is almost independent of the cycling frequency.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Nanoscience & Nanotechnology
Lu Yang, Saranarayanan Ramachandran, Axieh Bagasol, Qiyu Guan, Weiguang Wang, David J. Browne, Denis Dowling, Wajira Mirihanage
Summary: Laser powder bed fusion (LPBF) technology enables the production of metallic components without conventional design and manufacturing constraints. By reconstructing the as-solidified microstructure across the LPBF build volume, the initial solidification microstructure of Ti-6Al-4V alloy can be revealed, providing insights into the early stages of solidification. This approach also has the potential to explore solidification microstructure and defect formation in titanium alloys during additive manufacturing.
SCRIPTA MATERIALIA
(2023)
Article
Materials Science, Multidisciplinary
X. X. Yao, X. Gao, Z. Zhang
Summary: Remelting and grain growth have a significant impact on microstructural evolution during the multilayer printing process. The study found that undercooling determines the extent of heterogeneous nucleation and controls the columnar-to-equiaxed transition (CET). Thermal undercooling contributes more to grain formation, and increasing build height is beneficial for CET. Additionally, decreasing the scanning velocity leads to grain coarsening.
JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T
(2022)
Article
Materials Science, Multidisciplinary
Xinyu Yang, Richard A. Barrett, Noel M. Harrison, Sean B. Leen
Summary: A physically-based, mixed-phase structure-property model is developed for analyzing the microstructure-sensitivity of tensile stress-strain response in additively manufactured Ti-6Al-4V, considering the effects of solutes, grain size, phase volume fraction, and dislocation density. The model incorporates solid-state phase transformation and dislocation density evolution to simulate the effects of martensite dissolution and a -b transformation at high temperature, allowing for rapid process-structure-property prediction and optimization.
MATERIALS & DESIGN
(2021)
Article
Nanoscience & Nanotechnology
M. Doroszko, A. Falkowska, A. Seweryn
Summary: This work focuses on numerically modeling the deformation process and mechanical properties of structures obtained by LPBF, using geometric models and CT/micro-CT to map realistic shapes. The study investigates the relationship between shape accuracy and mechanical properties, as well as identifies fracture initiation locations in titanium cellular structures, with results verified by experimental tests.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Mechanics
Emre Akgun, Xiang Zhang, Tristan Lowe, Yanhui Zhang, Matthew Dore
Summary: Defects in metal additive manufacturing play a significant role in causing failure under cyclic loading, with crack-initiating defects often located at the lower end of a positive-skewed size distribution and showing a tendency towards the free surface. By measuring fatigue crack growth rates using the replica technique, it was found that crack initiation life from porosity can contribute to at least 50% of the total fatigue life. These findings challenge the common assumption of crack initiation from the very first cycle and emphasize the importance of considering defects in predicting fatigue life.
ENGINEERING FRACTURE MECHANICS
(2022)
Article
Chemistry, Analytical
Yihang Cui, Jiacheng Cai, Zhiguo Li, Zhenyu Jiao, Ling Hu, Jianbo Hu
Summary: Additive manufacturing is a rapidly developing manufacturing technology that allows for active control of the microstructure of materials. The study shows that the porosity of materials significantly affects their dynamic response.
Article
Materials Science, Multidisciplinary
William J. Davids, Hansheng Chen, Keita Nomoto, Hao Wang, Sudarsanam Babu, Sophie Primig, Xiaozhou Liao, Andrew Breen, Simon P. Ringer
Summary: The study reveals significant variations in beta phase fraction within a given build and categorizes high-temperature beta phase into two types based on their formation temperature, providing new insights into the phase transformation pathway during additive manufacturing.
Article
Nanoscience & Nanotechnology
Atasi Ghosh, Vivek Kumar Sahu, Nilesh Prakash Gurao
Summary: The ratcheting behavior of additively manufactured and thermo-mechanically treated Ti-6Al-4V alloy was investigated. The as-built additively manufactured sample showed a lower fatigue life compared to the thermo-mechanically treated sample, and this decreased further after heat treatment. The combined hardening model in the Finite Element Method could not accurately predict the macroscopic stress-strain behavior of the additively manufactured alloy due to the heterogeneous evolution of microscopic strain. The presence of multi-variant needle-shaped martensite was found to increase crack propagation resistance and fatigue life in the as-built additively manufactured alloy.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2022)
Article
Engineering, Manufacturing
O. Dolev, S. Osovski, A. Shirizly
Summary: The tensile behavior and fracture toughness of a hybrid Ti-6Al-4V alloy were examined, showing good properties without a preference for crack growth. The hybrid manufacturing approach studied here expands the current limitations of large-scale critical components and allows for higher throughput.
ADDITIVE MANUFACTURING
(2021)
Article
Engineering, Manufacturing
Mohammadreza Asherloo, Ziheng Wu, Melody H. Delpazir, Eyob Ghebreiesus, Sara Fryzlewicz, Runbo Jiang, Benjamin Gould, Mike Heim, Dave Nelson, Mike Marucci, Muktesh Paliwal, Anthony D. Rollett, Amir Mostafaei
Summary: This study compares the performance of HDH Ti-6Al-4V powders with different size distributions and reveals that a suitable combination of laser power-velocity-hatch spacing can achieve part production with a relative density of > 99.5%. Analysis shows that the lower packing density of coarse powder and high keyhole fluctuation result in higher proportions of porosity within builds during the LB-PBF process.
ADDITIVE MANUFACTURING
(2022)
Article
Chemistry, Physical
Michal Doroszko
Summary: This study investigates the influence of defects in struts under tension, obtained using the laser powder bed fusion method, on stress and strain distributions. The results show that micronotches on the external surface have a greater impact on stress and strain distribution compared to micropores inside. Additionally, the interactions between defects also affect stress distributions and the formation of high-stress bands inside the material.
Article
Materials Science, Multidisciplinary
Weizhao Sun, Feihu Shan, Nanfu Zong, Hongbiao Dong, Tao Jing
Summary: This research investigates the phase transformation of Ti-6Al-4V during wire laser additive manufacturing using a density-based constituent phase simulation method. By increasing temperature and decreasing cooling rate, the undesirable alpha' phase can be narrowed or even eliminated. Additionally, the laser power of 3000 W results in more transformed alpha(B) without increasing alpha-lath thickness compared to the 2500 W case. The simulation shows promising prospects in predicting phase transformation and optimizing processing parameters.
MATERIALS & DESIGN
(2021)
Article
Materials Science, Multidisciplinary
Z. K. Feng, Y. Hong, G. Wang, X. H. Wu, D. C. Zeng
MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING
(2018)
Article
Materials Science, Multidisciplinary
X. H. Wu, G. Wang, L. Z. Zhao, Y. Hong, Z. K. Feng, D. C. Zeng
MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING
(2018)
Article
Materials Science, Multidisciplinary
Hao Li, Gang Wang, Zhaoguo Qiu, Zhigang Zheng, Dechang Zeng
Summary: The effects of alloy composition, cooling rate, and external magnetic field on the microstructures and magnetic properties of Nd-Fe-B alloy are investigated. The regional distribution in the alloy is formed due to the temperature gradient. Nd19Fe71.5B9.5 (at%) exhibits the highest coercivity and good magnetic properties. Cooling rate affects grain size and amorphous phase. Applying an external magnetic field can enhance the coercivity and remanence.
ADVANCED ENGINEERING MATERIALS
(2023)
Article
Chemistry, Physical
Wenjie Yang, Junjie Liu, Xiangfeng Yu, Gang Wang, Zhigang Zheng, Jianping Guo, Deyang Chen, Zhaoguo Qiu, Dechang Zeng
Summary: This paper investigates the influence of thickness and deposition temperature on the magnetic properties of FeCo thin films. The results show that increasing the film thickness and deposition temperature can significantly reduce the coercivity and increase the saturation magnetization. Especially for thicker films, high-temperature deposition has a more pronounced effect on improving the soft magnetic properties.
Article
Physics, Applied
L. Huo, R. Schiedung, H. Li, G. Wang, Y. Hong, A. Gruenebohm, I Steinbach
Summary: There is a need to optimize the microstructure of magnetic materials used in wind turbines and electric motors, which depends on the microstructure evolution during sintering or heat treatment. Most simulation packages do not allow for simultaneous modeling of both the structural and magnetic degrees of freedom. Therefore, we extend an open-source software project to implement the necessary micromagnetic equations and apply it to field-assisted grain growth in Sm2Co17 polycrystal films.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Chemistry, Physical
Z. G. Zheng, X. L. Chen, H. Y. Wang, S. Da, G. Wang, Z. G. Qiu, D. C. Zeng, Q. B. Xia
Summary: In this study, high-entropy alloys (MnNiSi)1-x(FeCoGe)x (x = 0.4, 0.42, 0.45, and 0.47) were designed and the effects of the Si/Ge ratio on the magnetocaloric effect and mechanical properties were investigated. The high-entropy alloy (MnNi)0.6Si0.62(FeCo)0.4Ge0.38 exhibited a significant entropy change of 48.5 JGreek ano teleiakg � 1K-1, Vickers hardness value of 580.6HV2, and compressive strength of 267 MPa under a magnetic field of 5 T near the Curie temperature of 308.8 K. The influence mechanism of crystal structure and configurational entropy on the excellent comprehensive performance was explored.
JOURNAL OF ALLOYS AND COMPOUNDS
(2023)
