Papers by Keyword: Homogenization

Abstract: Interpenetrating Phase Composites (IPCs) with biomimetic properties are promising materials for strengthening orthopaedic implants while also increasing their biocompatibility. Thanks to additive manufacturing techniques, lattice structures can be employed to develop biomaterials with controlled architectures, enabling the replication of human bone structures and offering advantages in terms of strength-to-weight ratio. This study investigates the behaviour of a bi-material steel-polymer lattice structure, observing that the epoxy resin increases the mechanical strength of gyroid, leaving the lightweight properties unchanged. Moreover, an equivalent constitutive model was calibrated, and a homogenization procedure based on the Representative Volume Element theory was applied. The effect on mechanical strength due to the 316L powder dispersed within the epoxy resin was investigated as well.

Abstract: Microstructural evolution during D.C. casting and subsequent homogenization of non-heat-treatable aluminium alloys involves complex phenomena, including micro-segregation of alloying elements and intermetallic phase selection during solidification as well as phase transformations of both primary (constituents - intergranular) and secondary (dispersoids - intragranular) intermetallic phases. In this study, we simulated the microstructural evolution of AA3003 using a CALPHAD-based modelling framework implemented in ThermoCalc®. The framework integrates a Scheil-Gulliver solidification model coupled with a 1-D micro-segregation alleviation and diffusional phase transformation model (DICTRA®) and a Kampmann-Wagner Numerical (KWN) model for dispersoid precipitation (TC-PRISMA®). According to this approach, the development of a robust computational methodology is aimed at accurately predicting the influence of homogenization cycles on dispersoid precipitation, which in turn affects recrystallization behaviour via the well-known Smith-Zener drag phenomenon. Additionally, these CALPHAD-based simulations facilitate the assessment of impurity content effects on dispersoid precipitation, considering the increasing use of scrap in the fabrication of non-heat-treatable aluminium alloys. Furthermore, they provide precise estimates of Smith-Zener pinning forces as inputs for downstream mesoscale full-field process models, contributing to a holistic through-process modelling approach.

Abstract: This work presents a theoretical and numerical study on the nonlinear free vibrations of orthotropic laminated composite beams, with a focus on different material orientations such as cross-ply, balanced, and woven configurations. Based on the Euler-Bernoulli beam theory and Von Karman’s geometric nonlinearity, we develop an analytical and matrix formulation using Hamilton’s principle. The novelty lies in the use of a homogenization approach to derive equivalent stiffness properties, allowing the comparison between symmetrical and asymmetrical composite beams. Despite limitations inherent to Euler-Bernoulli assumptions, results show the significant influence of layer orientation on the nonlinear frequency and displacement behavior. This study is valuable for structural applications in aerospace and mechanical systems.

Abstract: Out-of-furnace treatment of steel has many possibilities for correcting the iron-carbon semi-product obtained at the previous stage of steel production. This is ensured both by various methods of maintaining the temperature and by introducing the necessary correcting or modifying additives into the ladle with subsequent averaging stirring of the melt. At the same time, the bottom type of purging through one or more purging units became the most widespread. The paper presents the results of research on the nature of the flows created during bottom purging through a block with non-directional porosity. The research was conducted with the help of a full-scale physical model using water as a model fluid and using the conductometric method of establishing the homogeneity of the liquid bath and dissolution additives of the “heavy” type (using NaCl salt for modelling). Those additives dissolve mostly at the bottom and, for their volume distribution, require the creation of sufficient mixing flows. The study was carried out at different intensities of gas supply for purging according to the purging modes corresponding to industrial conditions. It was established that during purging in the bubbling mode through a block with non-directional porosity, the largest change in concentration during purging occurs in the volume of the liquid bath at the level of more than 25% from the bottom of the ladle. A large change in concentration indicates a significant volume of dissolution of “heavy” additives that dissolve at the bottom. This can be explained by the formation of conditions for the spiral rotation of the grouped bubble flow that breaks into individual bubbles at a distance of approx. 75% from the bottom of the ladle. Such flows create active horizontal mixing of the liquid bath. The best conditions for mixing the liquid bath, under conditions of addition of “heavy” additives that dissolve at the bottom, with the shortest homogenization time among the studied conditions were purging with an intensity of gas supply of 0.684-1.026 m³/t steel per h.

Abstract: Homogenization treatment is usually indispensable to obtain a good microstructure pattern and brilliant final performance of Al-Cu-Li alloys. In the present study, the effect of different Mg contents on the microstructure of Al-Cu-Li alloys during homogenization was investigated utilizing optical microscopy (OM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analysis. The results indicated that the higher Mg content changed the type of grain boundary phase in the as-cast alloy. The eutectic phases in the low Mg alloy were dominated by Cu-rich phases while the high Mg alloy also had many Ag-containing Al₂CuMg phases. The difference in Mg contents did not affect the grain morphology, while the high Mg content in the Cu-rich phase caused a decrease in its melting point. Suitable homogenization treatments for the low and high Mg alloys are 520 °C/12 h and 495 °C/24h + 505 °C/48 h, respectively. This provides a reference for studies related to the effect of composition evolution on the dissolution of the second phase during the homogenization treatment.

Abstract: The dissolution of second phase with relatively high melting point in as-cast Al-Zn-Mg-Cu alloys was closely related to Mg and Cu contents. In present work, second phases in three Al-Zn-Mg-Cu alloys with simultaneously enhanced Mg and Cu contents (named by LMC alloy, MMC alloy and HMC alloy as Mg and Cu contents progressively enhanced) were analyzed and the correlated dissolution during homogenization was investigated. The results showed that both Mg(Zn,Cu,Al)₂ phase and Cu-rich phase existed in as-cast alloys while HMC alloy possessed more eutectic phases. As homogenized by 470°C/24h, Mg(Zn,Cu,Al)₂ phase had dissolved completely, LMC alloy contained little Al₂CuMg phase and the amount of it for the three alloys was arranged as LMC alloy < MMC alloy < HMC alloy. As furtherly homogenized by a second stage at 480°C for 12h, no endothermic peak for Al₂CuMg phase was observed for LMC alloy and only Fe-rich phase existed. Meanwhile, Al₂CuMg phase still remained in MMC and HMC alloy. As the homogenization time prolonging to 36h, Al₂CuMg phase in MMC alloy dissolved completely while that still existed in HMC alloy. Adding a third stage at 490°C for HMC alloy, no Al₂CuMg phase could be observed for 24h. This gave rise to a method by incrementally grading homogenization temperature combined with prolonging soaking time to fulfill the dissolution of second phase for Al-Zn-Mg-Cu alloys with enhanced Mg and Cu contents

Abstract: Homogenization treatment is vital for eliminating eutectic structure and ensuring a preferable microstructure foundation for Aluminum Lithium (Al-Li) alloys. In this paper, solidification phases in an as-cast Al-Li alloy were revealed and their evolutions during multiple homogenization processes were analyzed by means of scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and differential scanning calorimetry (DSC) analysis. The results showed that the as-cast microstructure mainly contained needlelike Al₂CuLi and Al₂Cu phase, large size Cu-rich phases and netlike Ag-containing phases attached to them. As the alloy homogenized by 455°C/16h, except for needle-like phases inside grains, part of phases on grain boundaries had dissolved into the matrix and exhibited rounded shapes. As homogenized by 455°C/16h+495°C/16h, Ag-containing phase had completely dissolved into the matrix while the Cu-rich phases remained and showed two different morphologies depending on whether Mg element was contained. Prolonging the second homogenization time to 28h, no obvious change occurred for the Cu-rich phase. As homogenized by 455°C/16h+495°C/20h+512°C/20h, most Cu-rich phase had dissolved into the matrix while residual phase was mainly Fe-containing phase. This proposes an effective way to eliminate various solidification phases in Al-Li alloys and identify their contents.

Abstract: The effect of Zn/Mg ratio on the as-cast microstructure and its evolution during homogenization of Al-Zn-Mg-Cu alloys was investigated by optical microscopy (OM), differential scanning calorimetry (DSC), scanning electron microscope (SEM) and X-ray diffraction (XRD). Experimental results showed that serious dendritic segregation existed in the as-cast microstructures while the second phases were mainly AlZnMgCu phase and Al₂Cu phase. With the Zn/Mg ratio increasing from 1.5 to 2.0, the area fraction of AlZnMgCu phase decreased from 2.85% to 2.53%, which was attributed to the content of Mg element. Non-equilibrium eutectic phases dissolved into the matrix during homogenization and phase transformation from AlZnMgCu phase to Al₂CuMg phase (S phase) was observed in low-Zn/Mg ratio alloy and mid-Zn/Mg ratio alloy. In the high Zn/Mg ratio alloy, the eutectic AlZnMgCu phase directly dissolved into the matrix during the homogenization, and no transformation from AlZnMgCu phase to S phase was found. A higher number of S phases appeared in low-Zn/Mg ratio alloy during homogenization treatment compared with mid-Zn/Mg ratio alloy with a regime of 465°C/24h. It could be inferred that low-Zn/Mg ratio alloys had a stronger phase transformation tendency from AlZnMgCu phase to S phase. Increasing the homogenization treatment temperature could impair the transition tendency from AlZnMgCu phase to S phase.

Abstract: The microstructures of as-cast and homogenized Al-Cu-Mg-Ag alloys with 1.98, 3.66 and 5.16 wt.% Cu contents (Alloy 1, Alloy 2, Alloy 3, respectively) were investigated by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and calculation of phase diagram. The results indicate that the second phases in the as-cast alloys consist of θ (Al₂Cu), ternary α (Al)-θ (Al₂Cu)-S(Al₂CuMg) eutectic and Fe-enriched phase. The invariant reactions are L→α (Al) + θ (Al₂Cu) at 542°C and L→α (Al) + θ (Al₂Cu) + S(Al₂CuMg) at 505°C during solidification. An increase of Cu content promotes the formation of θ (Al₂Cu) phase, therefore leading to the total second phases increasing in the as-cast alloys. The ternary eutectic completely dissolves into the matrix after the first-step homogenization at 490°C, and θ (Al₂Cu) phase dissolves subsequently after the second-step homogenization at 510°C. It is suggested that the proper homogenization treatments are 490°C/24 h for Alloy 1, 490°C/24 h + 510°C/24 h for Alloy 2 and 490°C/24 h + 510°C/48 h for Alloy 3.

Abstract: Development an ingot originated from the waste of aluminum product had many the advantages and could reduce the cost of aluminum metal production compared to primary process from ore. In this research used the waste of beverage aluminum cans One of the manufacturing methods conducted recycling aluminum waste is the casting process, Commonly, the problem with this casting process was that they are not homogeneous in the as-cast due to segregation. So that in this study a homogenization process on recycling aluminum castings would be carried out to obtain more homogeneous mechanical properties and microstructure. The variables that influence during the homogenization process was heating temperature and holding time. The heating temperature for this was in range from 450 C to 550 C, and the holding time was 2 to 4 hours. Further the effect of the parameter would observe. The observation included mechanical properties, such as tensile strength and hardness, and Microstructure of the ingot. The operation temperature and holding time influenced to grain size and hardness of Aluminum. In general, increasing homogenization temperature would reduce mechanical properties.