Article
Chemistry, Physical
Cezary Rapiejko, Dominik Mikusek, Bartlomiej Januszewicz, Krzysztof J. J. Kubiak, Tadeusz Pacyniak
Summary: The microstructure of AZ91 magnesium-aluminium alloy was refined by inoculating with zirconium. A zirconium content concentration of 0.3 wt% resulted in shortened solidification time and further refinement of the microstructure.
Article
Metallurgy & Metallurgical Engineering
John Samson Khalkho, Suresh Vidyasagar Chevuri, Benny Karunakar Dagarapu
Summary: This study investigates the effect of TiO2 particles on the microstructure and mechanical properties of AA2014 composites. It is found that TiO2 promotes grain refinement and reacts with Al to form Al2O3, which improves the strength of the composites. The composite sample with 4wt% TiO2 exhibits the best combination of mechanical properties.
INTERNATIONAL JOURNAL OF METALCASTING
(2023)
Article
Nanoscience & Nanotechnology
Qiyang Tan, Zhiqi Fan, Xiaoqin Tang, Yu Yin, Gan Li, Danni Huang, Jingqi Zhang, Yingang Liu, Feng Wang, Tao Wu, Xianliang Yang, Han Huang, Qiang Zhu, Ming-Xing Zhang
Summary: The study proposed a novel strategy combining substrate modification and inoculation treatment to successfully fabricate crack-free and dense high-strength 7075 alloy using SLM. This strategy can be implemented for SLM of other engineering alloys, providing a foundation for broadening industrial applications of SLM.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Materials Science, Multidisciplinary
Cheng Zhu, Zhihao Zhao, Qingfeng Zhu, Gaosong Wang, Yubo Zuo, Qiangqiang Li, Gaowu Qin
Summary: The study proposes a technique called double-cooling field casting to address the issues of microstructure inhomogeneity and negative segregation in large-size alloy ingots. Experimental results show that the introduction of a solid insert improves grain refinement, reduces segregation, and enhances the quality of the ingot.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2022)
Article
Metallurgy & Metallurgical Engineering
C. Vian, C. Kibbey, Y. Chen, C. Kuntz, Q. Han
Summary: Die cast alloys require high pouring temperatures to avoid dendrite formation, but forming globular grains can reduce the pouring temperature and improve die life. This study successfully produced globular grains in a shot sleeve using a water-cooled ultrasound trough, which may have applications in die casting and other gravity casting processes.
INTERNATIONAL JOURNAL OF METALCASTING
(2022)
Article
Chemistry, Physical
Yukang An, Xiaolong Xu, Lei Liang, Yuhong Zhao, Hua Hou
Summary: The rapid solidification of Ni-Cu alloy was studied, revealing changes in grain refinement with increased undercooling, indicating the occurrence of recrystallization. The grain refinement at large undercooling is mainly caused by stress-induced recrystallization.
JOURNAL OF ALLOYS AND COMPOUNDS
(2021)
Article
Automation & Control Systems
Argos Soares Silva, Sarah Maria de Albuquerque Sousa, Guilherme Lisboa de Gouveia, Amauri Garcia, Jose Eduardo Spinelli
Summary: The effects of NbB addition on grain size, secondary dendrite arm spacing, and hardness of 2017 alloy samples were investigated. The results showed that the grain size decreased while the secondary dendrite arm spacing increased in DS samples, under similar cooling rates. Moreover, the grain size had little influence on the hardness of the alloys studied.
INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
(2023)
Article
Materials Science, Multidisciplinary
Mahdieh Jahanbakhshi, Salman Nourouzi, Reza Naseri, Kourosh Esfandiari
Summary: This study investigates the simultaneous use of cooling slope and mechanical vibration during solidification to improve the microstructure of as-cast A356 aluminum alloy. The results show that by using both cooling slope and mechanical vibration, finer grains can be achieved compared to using these two procedures separately. In the experimental conditions of 20 Hz vibration frequency and 3 minutes duration, an average grain size of 50 μm and a shape factor of 0.66 were obtained, while the mechanical properties of the alloy were also enhanced.
METALS AND MATERIALS INTERNATIONAL
(2022)
Article
Chemistry, Physical
M. H. Khan, A. Das, Z. Li, H. R. Kotadia
Summary: The effects of adding iron, manganese, and Al-5Ti-1B grain refiner on the solidification microstructures of 6082 alloy under different cooling rates were studied. It was found that iron and manganese can promote the refinement of primary-Al grains, but also increase the content of intermetallics, while Al-5Ti-1B grain refiner can effectively refine primary-Al grains and improve the microstructure by enhancing the nucleation of intermetallics and restricting their growth.
Article
Materials Science, Multidisciplinary
Tong Liu, Maoliang Hu, Qingyu Ran, Bo Jiang, Zesheng Ji, Xiaobing Zhou
Summary: A novel aluminum alloy refining agent was prepared using materials generated during a machining process, and the effect of temperature and time on the second phase was investigated. The results showed that the refining agent could effectively decrease the grain size of aluminum alloy and increase its tensile strength.
Article
Materials Science, Multidisciplinary
Yuan Li, Jinxiang Liu, Qiang Zhang, Weiqing Huang
Summary: The study reveals that the thick walls and junctions between thick and thin walls in cylinder heads are the main regions for porosity defects, and decreasing the cooling rate can reduce the secondary dendrite arm spacing (SDAS) of the casting, resulting in a dense microstructure. Furthermore, regular shapes and thin walls are advantageous for reducing porosity defects and obtaining uniform microstructures.
MATERIALS TODAY COMMUNICATIONS
(2021)
Article
Materials Science, Multidisciplinary
Jianhua Wu, Jixue Zhou, Shouqiu Tang, Xitao Wang, Qingyou Han
Summary: This study focused on using a simple quench method to study the effect of ablation water cooling on microstructural features and heat treatment response of A356 alloy. The results indicate that the simple method is suitable in simulating certain features of eutectic solidification during ablation casting, and the heat treatment response of water cooled samples is much faster than that of conventional castings. This could lead to reduced energy consumptions and significant cost savings if the heat treating process is optimized for ablation casting.
Article
Metallurgy & Metallurgical Engineering
M. E. Moussa, M. Amin, Khaled M. Ibrahim
Summary: The effect of ultrasonic vibration treatment on the microstructure and mechanical properties of brass alloy was investigated. The treatment significantly refined the microstructure and improved the mechanical properties, including yield strength, ultimate tensile strength, elongation, hardness, and wear resistance.
INTERNATIONAL JOURNAL OF METALCASTING
(2023)
Article
Materials Science, Multidisciplinary
Jianyue Zhang, Guanyu Zhou, Bin Jiang, Alan Luo, Xuzhe Zhao, Aitao Tang, Fusheng Pan
Summary: The novel grain refinement method using a CaMgSn intermetallic phase was found to effectively reduce the average grain size in AZ31 magnesium alloy, improving microhardness and compressive yield strength. The added CaMgSn particles acted as heterogeneous nucleation sites in the grain interiors, contributing to the refinement of microstructure and mechanical properties of Mg-Al-based alloys.
Article
Materials Science, Multidisciplinary
Sebastian Samberger, Irmgard Weissensteiner, Lukas Stemper, Christina Kainz, Peter J. Uggowitzer, Stefan Pogatscher
Summary: This study presents age-hardenable, fine-grained AlMgZnCu crossover alloys intended for superplastic and quick plastic forming processes. These alloys utilize T-phase (Mg32(Al,Zn)49) to refine the grain structure and increase age-hardening. The study demonstrates the importance of particle stimulated nucleation (PSN) using T-phase particles, which leads to a fine grain size as low as 4 μm. The resulting alloys have excellent high-temperature forming properties and high stability.
Article
Materials Science, Multidisciplinary
Reza Haghayeghi, Giulio Timelli
Summary: The experimental results indicate that stacking fault and kinks, in addition to twinning, contribute to primary Si refinement in A390 hypereutectic Al alloy. The type of alloying element determines the major contributing mechanism in primary Si evolution. Furthermore, the kink formation and its effect on primary Si refinement has yet been reported elsewhere.
Article
Automation & Control Systems
Giulia Scampone, Raul Pirovano, Stefano Mascetti, Giulio Timelli
Summary: This research aimed to study the formation and distribution of oxide-related defects in the gravity die casting process of an AlSi7Cu0.5Mg alloy. Experimental and numerical investigations were used, showing that most defects were correlated with oxide layers or bubbles entrained inside the liquid metal. The numerical simulations accurately predicted the formation of oxide-related defects.
INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
(2021)
Article
Nanoscience & Nanotechnology
Alessandro De Mori, Giulio Timelli, Alberto Fabrizi, Filippo Berto
Summary: The addition of Cu significantly improved the thermal stability and tensile/fatigue properties of AlSi7Mg0.3VZr alloy, but decreased ductility and changed fatigue failure mode.
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
(2021)
Article
Chemistry, Physical
Jacopo Fiocchi, Chiara Colombo, Laura Maria Vergani, Alberto Fabrizi, Giulio Timelli, Ausonio Tuissi, Carlo Alberto Biffi
Summary: This study explores the effect of stress relieving heat treatment on the microstructure, tensile properties, and residual stresses of laser powder bed fused AlSi9Cu3 alloy. Low temperature heat treatments are found to be desirable for promoting stress relaxation and limiting grain growth to achieve the best compromise between high strength, good elongation to failure, and limited residual stresses. Furthermore, a 59% reduction in principal residual stresses can be achieved after a 25-hour treatment, indicating a correlation with mechanical behavior.
Review
Materials Science, Multidisciplinary
Giulia Scampone, Giulio Timelli
Summary: Compared with pure aluminum and wrought aluminum alloys, anodizing Al foundry alloys is more challenging due to the high content of alloying elements, which hinders the uniform growth of the Al oxide layer and promotes the embedding of defects in the anodic film. The microstructure of the substrate and the anodizing parameters play a crucial role in determining the quality of the oxide layer. Variations in chemical composition, casting process, and pre- and post-anodizing treatments have significant effects on the anodizing response.
ADVANCED ENGINEERING MATERIALS
(2022)
Review
Materials Science, Multidisciplinary
Zohrehsadat Noohi, Simin Nosouhian, Behzad Niroumand, Giulio Timelli
Summary: Phase Change Materials (PCMs) are materials that release or absorb latent heat during their solid/liquid transformation and can be used for heating or cooling. Metallic PCMs, which have high conductivity, high latent heat storage capacity and chemical compatibility with containers, are considered the best alternative. This paper reviews the latest research achievements in low-melting point metallic PCMs and evaluates the criteria for selecting PCMs and containers.
Article
Materials Science, Multidisciplinary
Ozen Gursoy, Giulio Timelli
Summary: The effects of Bi content as a trace element on the microstructure and solidification path of A356.2 alloy have been studied. Alloys with different Bi levels (0, 20, and 200 ppm) were modified by sodium. Thermal analysis, metallography, and image analysis techniques were used to analyze the microstructural changes. The presence of Bi as a trace element affected the eutectic structure, with increased Bi levels raising the nucleation and growth temperatures of eutectic Si and coarsening the eutectic Si particles in Na-modified alloys.
ADVANCED ENGINEERING MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Cecilia Monticelli, Federica Zanotto, Andrea Balbo, Vincenzo Grassi, Alberto Fabrizi, Giulio Timelli
Summary: This research examined the corrosion behavior and susceptibility to stress corrosion cracking (SCC) of a high-pressure die-cast secondary AlSi9Cu3(Fe) alloy in 3.5% NaCl solution. Various testing methods revealed the presence of critical surface segregation zones, where strong corrosion attack occurred due to composition differences and peculiar morphology of noble Al2Cu phases. No SCC susceptibility was detected, but localized corrosion attack and hydrogen gas bubbling were observed at the interphases of noble phase/alpha-Al matrix.
Review
Materials Science, Multidisciplinary
Veronica Milani, Giulio Timelli
Summary: Aluminum recycling is a viable solution to address environmental and economic concerns. However, challenges exist in the process, including metal losses due to oxidation and the removal of impurities. This study provides an overview of the latest progress in using solid salt fluxes for secondary aluminum production and treatment of molten metal. The efficiency of solid fluxes depends on various factors, and their impact on metal cleanliness and recovery has been summarized.
Article
Metallurgy & Metallurgical Engineering
G. Scampone, G. Timelli, R. Pirovano, S. Mascetti
Summary: This study investigated the formation of entrainment defects in gravity permanent mould casting process through experiments and numerical simulations. The results showed that the entrainment of bifilms was the main cause of casting defects, and the numerical models successfully predicted the formation of oxide inclusions and the entrapment of air bubbles.
METALLURGIA ITALIANA
(2022)
Proceedings Paper
Electrochemistry
Ozen Gursoy, Giulio Timelli
Summary: This study investigated the effective holding time and fading effect of Gd in AlSi7Mg alloy. The results showed that shorter holding time can produce eutectic Si refinement, while longer holding time leads to Gd settling, grain coarsening, and formation of larger eutectic Si flakes.
Proceedings Paper
Electrochemistry
Reza Haghayeghi, Giulia Scampone, Ozen Gursoy, Giulio Timelli
Summary: This study examined the effect of casting temperature and iron content on the microstructure of A380 aluminium alloy. The results showed that the dendrite arm spacing was not significantly affected by the different casting temperatures or iron contents. Furthermore, it was found that the precipitation of harmful beta-phase was suppressed above certain temperatures, and the dominant phase in the microstructure changed to blocky or Chinese script alpha-Fe compounds. Lower iron content and a casting superheat of 100 degrees C were found to result in a uniform microstructure and removal of detrimental beta-phase.
Article
Metallurgy & Metallurgical Engineering
O. Gursoy, G. Timelli
Summary: The effect of bismuth on Na-modified eutectic Si particles in an A356 alloy was investigated in this study. It was found that the T-N, T-Min, and T-G temperatures for the Al-Si eutectic reaction decreased after Na modification, and the level of modification in the alloy also varied with the Bi content. Interactions between Bi-Na-rich intermetallic compounds in the microstructure were also observed, forming binary or triple eutectic systems with more than one compound.
METALLURGIA ITALIANA
(2021)
Article
Metallurgy & Metallurgical Engineering
M. Merlin, D. Benasciutti, L. Lattanzi, A. Fortini, G. Timelli
Summary: In this study, a secondary AlSi11Cu2(Fe) alloy was diecast with a specifically designed die and subjected to uniaxial fatigue tests with different surface finishing. It was found that sand-blasting treatment significantly improved the fatigue strength of the alloy, while both surface finishing methods showed similar statistical dispersion in fatigue life.
METALLURGIA ITALIANA
(2021)
Article
Metallurgy & Metallurgical Engineering
Z. Noohi, B. Niroumand, G. Timelli
Summary: Solidification structure has a significant impact on the mechanical and physical properties of metallic materials, and controlling this structure is a primary focus for improving material performance. This study presents preliminary results of a new method using Phase Change Materials (PCMs) to control solidification structure during casting. Experimental and simulation methods showed that PCMs can affect the local solidification cooling rate of the aluminum alloy, resulting in differences in solidification structure compared to samples without PCMs.
METALLURGIA ITALIANA
(2021)