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Casting and Solidification of Light Alloys

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Nguyễn Gia Hào

Academic year: 2023

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The effect of alumina nanoparticles introduced into the melt by ultrasonic treatment of the melt on the structure, and the properties of pure aluminum were studied in [3]. The analysis of the effect of Al-Mg-Si solution processing on the transformation of β-AlFeSi particles into α-(FeMn)Si and the aging of the Al 6063 alloy were presented in [5]. In work [12], the structural and phase states of the TiAl system alloyed with rare earths were studied.

The structural and phase state of the TiAl system alloyed with rare earth metals from the controlled.

The Structural and Phase State of the TiAl System Alloyed with Rare-Earth Metals of the Controlled

Hydride Technology”

  • Introduction
  • Materials and Methods 1. Obtaining Alloys
  • Results and Discussion
  • Conclusions

The HT method makes it possible to avoid most of them (in particular, it excludes melting). The structural state and quantitative phase analysis of the TiAl-alloy metal (TA-REM) system synthesized by HT were studied in this work using the Rietveld method and scanning electron microscopy (SEM) [24,25]. The results of the quantitative content of the phases in the studied systems are given in Tables 1–4.

The tables also show the fraction of the calculated integrated intensity (Rwp) in the experimental diffractogram.

Figure 1. 3D lattice of the AlTi 3 alloy with the Y atom embedded in the site [0.5 0.5 0.5].
Figure 1. 3D lattice of the AlTi 3 alloy with the Y atom embedded in the site [0.5 0.5 0.5].

Microstructure of In-Situ Friction Stir Processed Al-Cu Transition Zone

  • Materials and Methods
  • Results
  • Discussion
  • Conclusions

Friction-stir processing was performed using the FSW machine (Sespel, Cheboksary, Russian) at the Institute of Strength Physics and Materials Science of the Siberian Branch of the Russian Academy of Sciences (Tomsk, Russian) (Figure 1). Improvement of microstructure, mechanical properties and corrosion resistance of cast Al-12Si alloy by friction stir processing.Trans. Effect of the processing parameters of friction stir processing on the microstructure and mechanical properties of 6063 aluminum alloy. Mater.

Microstructural characterization and properties of in situ Al-Al3Ni/TiC hybrid composite produced by friction stir processing using reactive powder. Mater. Fabrication of In-Situ Al-Cu Intermetallics on Aluminum Surface by Friction Stir Processing.Arab. Correction to: Formation of Al/(Al13Fe4+Al2O3) Nano-composites via Mechanical Alloying and Friction Stir Processing.

Microstructure and tribological performance of an aluminum alloy-based hybrid composite produced by friction stir processing. Mater. Fabrication and characterization of in-situ Al/Nb metal/intermetallic surface composite by friction stirrer processing. Mater. Effect of Pin Profile on Microstructure and Mechanical Properties of Friction Stir Spot Welded Al-Cu Dissimilar Metals.J.

The effect of ultrasonic vibrations on the formation of intermetallic compound layers in Al/Cu friction weld joints.J. Development of surface composite based on Al-Cu system by friction stir processing: Evaluation of microstructure, formation mechanism and wear behavior. Surf.

Table 1. Chemical composition of A5056 and C11000 plates.
Table 1. Chemical composition of A5056 and C11000 plates.

Microstructural Analysis of Friction Stir Butt Welded Al-Mg-Sc-Zr Alloy Heavy Gauge Sheets

The upper part of the stirring zone obtained on the 35 mm thick sheet still contains pores and discontinuities. Figure 4a shows the microstructure of sample 4.2 cut from the rear part of the exit hole, as shown in Figure 2. Kinking is also more pronounced in the lower parts of the TMAZ II where the FSW tool-induced metal flow pressure is higher.

The specifics of the TMAZ grain structure modification in the outlet hole area are shown in Figure 8. In the samples from the lower part of the joint (sections 3.5 and 3.6), the grains gradually grow from the stirring zone to the heat-affected zone (Figure 8a). This feature indicates different deformation and recrystallization processes at different distances from the FSW joint surface.

The samples cut off the central sections, with the exception of the section 1.7 sample, had a strength of about 355-365 MPa. Tests in the defect-free zone “S” (Figure 1) areas show that the ultimate tensile strength (UTS) of the specimens is around 350–390 MPa (Figure 11b). Excessive adhesion of the plasticized metal to the FSW tool can have detrimental effects on stirring and metal flow efficiency.

In addition, Figure 8a shows that some grain growth can occur near the SZ/TMAZ boundary. In the 30 mm thick sample, a stirring zone with a small lump formed along the entire length of the joint. Alternatively, it may be on the border of the rudder zone in the shoulder-driven region and in the pin-driven region.

The strength of the base metal in the tensile test in the rolling direction is 405 MPa, and 365 MPa in the transverse direction.

Figure 1. The friction stir welding (FSW) seam zones on a 35 mm thick AA1570 sheet (a), the FSW tool used for the 35 mm thick sheet after welding (b), the FSW tool used for the 30 mm thick sheet after welding (c), and the FSW tool used for the 35 mm thick
Figure 1. The friction stir welding (FSW) seam zones on a 35 mm thick AA1570 sheet (a), the FSW tool used for the 35 mm thick sheet after welding (b), the FSW tool used for the 30 mm thick sheet after welding (c), and the FSW tool used for the 35 mm thick

Wear of ZhS6U Nickel Superalloy Tool in Friction Stir Processing on Commercially Pure Titanium

Experimental Procedure

This process is similar to friction stir welding and differs only in the absence of a joint line between the two welded parts. Due to the friction between the tool and the workpiece, heating, plasticization and mixing of the material occurred. FSP was performed at constant axial load, which is a preset parameter to maintain metal flow on the tool.

The axial force on the tool during both plunging (Fpl) and processing (Fpr) was maintained at 7848 N, the traverse speed (V) was 180 mm/min, and the tool rotation rate (ω) was 950 rpm. Since the laboratory FSW machine was not attached with a liquid cooling system, unlike industrial machines, the processing was performed in successive 100 mm length passes to avoid overheating the tool. The FSP tool was not cleaned between passes so as not to interfere with the conditions created in the regular FSW process.

Qualitative as well as quantitative analysis of the weld and tool microstructure was performed using an Altami MET-1C metallographic microscope (Altami, St. Petersburg, Russia) and a Microtrac SM 3000 scanning electron microscope (Nikkiso Co. The worn surfaces of the tool were examined using an Olympus LEXT OLS4000 confocal microscope (Olympus, Tokyo, Japan). The tool was also photographed at intervals between passes to document its shape change.

Quasi-static tensile tests of the weld material were performed in a UTC 110M-100 testing machine (Testsystems, Ivanovo, Russia) at room temperature. Microhardness numbers were obtained to evaluate the local hardness in the stir zone and in the base metal.

Figure 1. Scheme of friction stir processing (a) and tool schematic (b).
Figure 1. Scheme of friction stir processing (a) and tool schematic (b).

Results and Discussion 1. Tool Wear

Figure 4 shows typical 3D images of the tool worn surfaces before machining and after traversing 2755 mm. Tungsten is also seen in deposited titanium layers, indicating the dispersion of the tool elements in the transfer layer. The highest wear is observed in the shoulder area at the base of the pin.

Figure 7 shows an SEM image of the axial section of the tool and EDX maps of Ti and tool elements. The maps demonstrate that the main elements of the tool are distributed in the contiguous titanium layer. This is probably due to the fact that titanium-rich layers are removed from the tool immediately during processing.

The shape of the arrays generally tends to be uniaxial after FSP both in the base material and in the tool. The thickness of the adhesive titanium layer on the tool is in the range of 30-80μm, which is consistent with the surface morphology measurements. Figure 9 shows SEM BSE images of the base ZhS6U alloy structure and the tool structure.

Processing quality here refers to the structure of the weld and its mechanical properties. Defect formation during tool wear can be avoided by changing machining parameters, eg, axial load.

Figure 3. General view of the tool before friction stir processing (FSP) (a), after traversing 1105 mm (b), 2335 mm (c), and 2755 mm (d).
Figure 3. General view of the tool before friction stir processing (FSP) (a), after traversing 1105 mm (b), 2335 mm (c), and 2755 mm (d).

Structure and Properties of Al–0.6 wt.%Zr Wire Alloy Manufactured by Direct Drawing of

Electromagnetically Cast Wire Rod

Experimental Methods

The specific electrical conductivity (EC) of the EMC rod and the cold-rolled strip was determined using the eddy current method with a VE-26NP vortex structure. The electrical resistivity (ER) of the EMC rod and strip was calculated from the EC data. Due to the high solidification rate of the cast ingot, the microstructure of the experimental alloy has a fine structure.

Iron-bearing particles in the form of thin veins were located along the borders of the dendritic cells. Annealing the cast rod at up to 400◦C did not make any visible changes in its microstructure. The hardness of the cold-rolled strip was higher compared to the hardness of the EMC rod (650 vs. 400 MPa).

In a range of 450–500◦C, the hardness of the EMC bar was much higher than that of the strip, but the difference decreased markedly with an increase in the annealing temperature. We assumed that the manufacturability of the as-cast EMC rod during drawing was very good. Figure 5 shows that the ER of the wire and the strip are very close after annealing.

The fracture surface of the experimental wire alloy has a homogeneous ductile pattern with fine dimples after the tensile test (Figure 8a). The size of the pits is significantly larger than the size of the iron-containing particles inside the pits (Figure 8b).

Figure 1. Processing root for experimental wire alloy (see Table 1). CD—cold drawing, A—annealing, R12—as-cast electromagnetic casting (EMC) rod, and W3—wire.
Figure 1. Processing root for experimental wire alloy (see Table 1). CD—cold drawing, A—annealing, R12—as-cast electromagnetic casting (EMC) rod, and W3—wire.

Summary

Funding: The study was conducted within the framework of the implementation of the Resolution of the Government of the Russian Federation of April 9, 2010 No. Acknowledgments: The results were obtained using the equipment of RPC Magnetic hydrodynamics LLC, Krasnoyarsk, Russia; Institute of Physics of Advanced Materials, Ufa State Aviation Technical University, Ufa, Russia; and Department of Metal Formation, National University of Science and Technology MISiS, Moscow, Russia. Effect of Zr additions and annealing temperature on electrical conductivity and hardness of hot-rolled Al plates.Trans.

In situ small-angle scattering study of the precipitation kinetics in an Al-Zr-Sc alloy. Three-dimensional atom probe study of the formation of Al3(Sc,Zr) dispersoids in aluminum alloys.Scrip. Precipitation kinetics of Al3Zr and Al3Sc in aluminum alloys modeled with cluster dynamics.Acta Mater.

Effect of heat treatments on microhardness and tensile strength of Al–0.25 wt.% Zr alloy.J. Dispersoid precipitation and process modeling in zircon containing commercial alumina alloys.Acta Mater. Distinctive features of the structure and properties of long bars of small cross-section from aluminum alloys cast in an electromagnetic mold).Tsvet. Structure and properties of Al–0.6%Zr–0.4%Fe–0.4%Si wire alloy (wt%) produced by electromagnetic casting.

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Figure 3. EDX-spectra and elemental composition of the TAY (a), TAT (b) and TAD (c) alloys.
Figure 4. Electron microscope images of the matrix of the initial alloy TA: (a) bright-field image;
Table 7. Crystallographic data of phases in the system TA.
Figure 5. Isothermal cross-sections of the TiAlY system at 1000 ◦ C [45] (a), of the TiAlDy system at 500 ◦ C [46] (b), of the TiAlTa system at 1100 ◦ C [47] (c).
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