scholarly journals Analysis of γ′ Precipitates, Carbides and Nano-Borides in Heat-Treated Ni-Based Superalloy Using SEM, STEM-EDX, and HRSTEM

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4452
Author(s):  
Łukasz Rakoczy ◽  
Bogdan Rutkowski ◽  
Małgorzata Grudzień-Rakoczy ◽  
Rafał Cygan ◽  
Wiktoria Ratuszek ◽  
...  
Keyword(s):  
X Ray Diffraction ◽  
Dendritic Microstructure ◽  
X Ray ◽  
Investment Cast ◽  
Solution Treated ◽  
Heat Treated ◽  
The Matrix ◽  
The Mean ◽  
Microscopy Techniques ◽  
M23c6 Carbides

The microstructure of a René 108 Ni-based superalloy was systematically investigated by X-ray diffraction, light microscopy, energy-dispersive X-ray spectroscopy, and electron microscopy techniques. The material was investment cast in a vacuum and then solution treated (1200 °C-2h) and aged (900 °C-8h). The γ matrix is mainly strengthened by the ordered L12 γ′ phase, with the mean γ/γ′ misfit, δ, +0.6%. The typical dendritic microstructure with considerable microsegregation of the alloying elements is revealed. Dendritic regions consist of secondary and tertiary γ′ precipitates. At the interface of the matrix with secondary γ′ precipitates, nano M5B3 borides are present. In the interdendritic spaces additionally primary γ′ precipitates, MC and nano M23C6 carbides were detected. The γ′ precipitates are enriched in Al, Ta, Ti, and Hf, while channels of the matrix in Cr and Co. The highest summary concentration of γ′-formers occurs in coarse γ′ surrounding MC carbides. Borides M5B3 contain mostly W, Cr and Mo. All of MC carbides are enriched strongly in Hf and Ta, with the concentration relationship between these and other strong carbide formers depending on the precipitate’s morphology. The nano M23C6 carbides enriched in Cr have been formed as a consequence of phase transformation MC + γ → M23C6 + γ′ during the ageing treatment.

Preparation of Plate-Like Bulk Beta Iron-Disilicide Crystals Using Metal to Semiconductor Phase Transition by Heat Treatment

2002 ◽  
Vol 749 ◽  
Author(s):  
Masato Osamura ◽  
Hidetaka Ishihara ◽  
Zhengxin Liu ◽  
Hisao Tanoue ◽  
Shirou. Sakuragi ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Chemical Vapor Transport ◽  
Annealing Duration ◽  
Bulk Crystals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Flat Surfaces ◽  
The Matrix ◽  
The Mean ◽  
Micro Analysis

ABSTRACTPlate-like β-FeSi2 bulk crystals with size of 10×10 mm2 and thickness of 1 mm were fabricated by annealing CVT (chemical vapor transport)-grown plate-like α-Fe2Si5 at 800°C in Ar atmosphere. Before annealing, α-Fe2Si5 crystals were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM) to be single crystals with flat surfaces. XRD measurements of β-FeSi2 crystals subjected to annealing showed that they had a po lycrystalline structure. The mean Fe/Si co mposit ion rat io of β-FeSi2 crystal measured by energy dispersive x-ray spectroscopy (EDX) was 31/69 and it was the same as that of α-Fe2Si5 bulk crystal before annealing. SEM, Raman scattering and electron probe micro-analysis (EPMA) measurements identified that there existed small Si precipitates mixed in the matrix of β-FeSi2 crystals. At annealing temperature of 800°C, the plate-like β-FeSi2 bulk was obtained even the annealing duration time was as short as 5 hours.

Effects of Zr on Microstructures and Properties of a β Matrix Mg-13Li-3Al-0.7Zr Alloy

2005 ◽  
Vol 488-489 ◽  
pp. 155-160 ◽  
Author(s):  
Bin Chen ◽  
Lin Ping Feng ◽  
Tie Tao Zhou ◽  
Pei Ying Liu ◽  
Huan Xi Li
Keyword(s):  
Tensile Properties ◽  
Grain Refinement ◽  
Age Hardening ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microstructure And Properties ◽  
Heat Treated ◽  
The Matrix ◽  
Cold Rolled ◽  
Zr Alloy

The effects of Al, Zr additions on the microstructure and properties of a β matrix Mg-Li-Al-Zr alloy of hot forged, cold rolled and heat- treated states have been systematically investigated. The tensile properties of the alloy was tested, and microstructure was studied by X-ray diffraction and SEM methods. The results showed that the addition of zirconium in the aluminum containing Mg-Li alloy was effective for grain refinement. The alloy containing zirconium of rolled state exhibited higher strength and satisfied ductility compared with the alloy without zirconium. The existence of zirconium in the alloy was mainly in the form of Al-Zr compounds of Al2Zr andAl3Zr. The reason for less age-hardening effect may be caused by the capture of aluminum by zirconium and as a consequent by the lake of aluminum in the matrix.

scholarly journals Microstructural evolution of a modified HP alloy: experimental and complementary computational study

2017 ◽  
pp. 5141-5145
Author(s):  
Sandra Simonetti ◽  
C. Lanz ◽  
G. Brizuela ◽  
A. Juan
Keyword(s):  
Computational Study ◽  
Microstructural Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Eutectic Carbides ◽  
The Matrix ◽  
Secondary Precipitates ◽  
M23c6 Carbides ◽  
Cast Condition

In this work is presented results of the microstructural characterization of austenitic stainless steel (HP series) modified with Nb, aged at temperatures of 750, 800, 850, 900 and 950oC in air at different times. Microstructural changes were analyzed using optical microscopy, scanning electron microscopy (SEM) equipped with (EDS), x-ray diffraction and Vickers hardness. In the as-cast condition, the microstructure consists of an austenitic matrix and eutectic carbides network, Cr, Nb-rich carbides. The Cr-rich carbides are M7C3 type, whereas, those rich in Nb are NbC. During aging, there is a second precipitation in the matrix of very fine needle form of M23C6 carbides, which leads to an increase in hardness. After that, the decreasing in hardness is associated with a coalescence phenomenon of the secondary precipitates. Computational modeling shows that M23C6 is lesser stable than M7C3 carbide.

Nickel oxide–silica and nickel–silica aerogel and xerogel nanocomposite materials

2000 ◽  
Vol 15 (10) ◽  
pp. 2187-2194 ◽  
Author(s):  
M. F. Casula ◽  
A. Corrias ◽  
G. Paschina
Keyword(s):  
Nickel Oxide ◽  
Sol Gel ◽  
Supercritical Drying ◽  
Nanocomposite Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
The Matrix ◽  
Drying Conditions ◽  
Microscopy Techniques

The sol-gel method was used to prepare nickel oxide–silica and nickel–silica nanocomposite materials and the corresponding silica matrices. Different drying conditions were used to obtain aerogel and xerogel materials. The samples were characterized by thermal analysis, x-ray diffraction, N2–physisorption, transmission electron microscopy techniques, and infrared spectroscopy. Aerogel samples had a much higher surface area than the xerogel samples; moreover, different supercritical drying conditions gave rise to a different porous structure, which influenced the size and distribution of the nanoparticles in the matrix.

Fracture Toughness of Tungsten Carbide Reinforced Fe-Matrix Surface Composites

2017 ◽  
Vol 898 ◽  
pp. 1453-1458
Author(s):  
Xi Zhang ◽  
Li Sheng Zhong ◽  
Xin Wang ◽  
Yun Hua Xu ◽  
Hong Wu ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Tungsten Carbide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Surface Composites ◽  
Heat Treated ◽  
Matrix Surface ◽  
The Matrix ◽  
Grey Cast

Tungsten carbide (WC) reinforced Fe-matrix surface composites were prepared by in-situ synthesis between tungsten plate and graphite in grey cast iron. The microstructure, fracture toughness, and fracture of the WC layer were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD) and the Vickers indentation technique, respectively. The results revealed that heat treated at 1125°C for 135min in argon atmosphere the main phase was WC with a bit of α-Fe. The fracture toughness (KIC) of the WC layer calculated using the Niihara’s equation, was 5.21 MPa·m1/2. Fractographic observations revealed that cracks propagated along the grain boundary under 2 kg loads. Moreover, both the WC particles and the interface between the WC layer and the matrix had a strong bonding strength.

Characterization and Dissolution of ZrTh3UO10 and Th3UO8 Ceramics

2002 ◽  
Vol 713 ◽  
Author(s):  
Gini Curran ◽  
Yoann Sevestre ◽  
Wendy Rattray ◽  
Patrick G. Allen ◽  
Ken R. Czerwinski
Keyword(s):  
Oxidation State ◽  
X Ray Diffraction ◽  
X Ray ◽  
Uranium Oxidation ◽  
Absorption Studies ◽  
The Matrix ◽  
Microscopy Techniques ◽  
Long Term Behavior ◽  
Electron Energy Loss ◽  
X Ray Absorption

ABSTRACTThoria-urania-zirconia ceramics were studied in order to investigate the long-term behavior of potential thorium fuels in a repository environment. The ceramics were prepared by coprecipitation of the metal salts. Zirconia was added to determine if further stabilization against dissolution of the thoria-urania system could be achieved. In addition, 0.5 wt% MgO was added to some samples to increase stability and density. The inclusion of Zr in the ceramics did not dramatically decrease the leaching of thorium from the matrix.Material properties of the ceramic were analyzed using electron microscopy techniques such as Energy Dispersive X-ray (EDX) analysis and Electron Energy Loss Spectroscopy (EELS). X-ray diffraction and synchrotron-based x-ray absorption studies including extended xray fine structure (EXAFS) and x-ray absorption near edge spectroscopy (XANES) were also used to reveal elements of the phase structure and chemistry of the ceramics. X-ray diffraction (XRD) and EDX show that these ceramics separate into a zirconium-based phase and an actinide-based phase with low mutual affinity of thorium and zirconium, as well as partial solubilization of uranium in zirconium. The comparison of EELS spectra collected for the ceramics with spectra collected for UO2 and U3O8 reference materials also allow the assessment of uranium oxidation state independently in the two separate phases. Assessment of the bulk oxidation state using XANES correlated well with the EELS analysis. Interatomic distances and the bulk crystal structure were determined using EXAFS.

Effect of Addition of Quasicrystals in the Formation of Geopolymer Matrix Composites

2012 ◽  
Vol 727-728 ◽  
pp. 1479-1484 ◽  
Author(s):  
Adiana Nascimento Silva ◽  
Jaqueline Dias Altidis ◽  
Romualdo Rodrigues Menezes ◽  
Tibério Andrade dos Passos ◽  
Silvio Romero de Barros ◽  
...  
Keyword(s):  
Sodium Aluminate ◽  
Matrix Composites ◽  
X Ray Diffraction ◽  
X Ray ◽  
Industrial Sectors ◽  
Lamellar Morphology ◽  
Geopolymer Matrix ◽  
Heat Treated ◽  
The Matrix ◽  
Diffraction Peaks

The geopolymer although being a recently discovered material, it is already present in many industrial sectors. This range of applications is due to the commitment of the scientific community to understand and manipulate the material, seeking a contribution in this regard, it has produced geopolymer matrix composites with quasicrystalline and reinforcement, Al62,2Cu25,5Fe12,3 in the proportion of 10%, 20% and 30% by volume. These composites were obtained by manual production and heat treated at 400 º C for two hours. The characterization was made with the aid of scanning electron microscopy (SEM) and x-ray diffraction (XRD). Diffractograms of composites without heat treatment showed characteristic peaks of the phases present in the matrix and reinforcement. For the composites with heat-treated, it was observed that besides the phases mentioned above the presence of diffraction peaks possibly associated phase silica sodium aluminate. The composite showed good interface quasicrystal / geopolymer, showing the existence of a phase with lamellar morphology in the treated material.

Effect of Ultrasonication on Synthesis of Forsterite Ceramics

2012 ◽  
Vol 576 ◽  
pp. 252-255 ◽  
Author(s):  
K.Y. Sara Lee ◽  
K.M. Christopher Chin ◽  
Ramesh Singh ◽  
C.Y. Tan ◽  
M.A. Hassan ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Crystallite Size ◽  
Ball Milling ◽  
Magnesium Oxide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
The Matrix ◽  
Processing Steps

The current study is to examine the effect of ultrasonication on the synthesis of forsterite (Mg2SiO4) powder. Ultrasonication and ball milling were performed using talc and magnesium oxide as starting precursors, followed by heat treatment to obtain forsterite. The X-ray diffraction results of the powders heat treated at 1200°C showed that the 2 hours ultrasonication followed by 3 hours ball milling was beneficial in retaining the forsterite phase in the matrix. The results were similar to ball milling for 10 hours prior to heat treatment. The derived powders also exhibited very fine crystallite size in the range of 28 to 35 nm thus indicating the viability of using ultrasonication as part of the processing steps in the synthesizing of forsterite ceramics.

Effect of Solution Treatment on Microstructure and Mechanical Properties in an Al-9.3Zn-2.0Mg-1.8Cu Alloy

2016 ◽  
Vol 877 ◽  
pp. 606-610
Author(s):  
Kai Wen ◽  
Bai Qing Xiong ◽  
Yong An Zhang ◽  
Xi Wu Li ◽  
Zhi Hui Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Solution Treatment ◽  
Second Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Residual Phase ◽  
Solution Treated ◽  
Treatment Parameter ◽  
The Matrix

The microstructure solution treated by various temperatures of 2h in as-extruded Al-9.3Zn-2.0Mg-1.8Cu alloy was investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) analysis. The mechanical properties treated at 465oC for various times were tested by room temperature tensile mechanical properties test. The results indicated that second phase of the as-extruded alloy mainly consists of Mg (Zn,Cu,Al)2 and Fe-rich phases. Mg (Zn,Cu,Al)2 phase completely dissolved into the matrix solution treated at 465oC or higher for 2h while residual phase was mainly Fe-rich phase. The mechanical properties treated at 465oC for various time were tested and optimized solution treatment parameter was chosen as 465°C/1.5h.

Research on Microstructure Evolution in Al-9.8Zn-2.0Mg-1.8Cu Alloy during Solution Treatment

2016 ◽  
Vol 879 ◽  
pp. 2336-2341
Author(s):  
Bai Qing Xiong ◽  
Kai Wen ◽  
Yong An Zhang ◽  
Xi Wu Li ◽  
Zhi Hui Li ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Solution Treatment ◽  
Electron Back Scatter Diffraction ◽  
Solution Time ◽  
Second Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Solution Treated ◽  
The Matrix

The microstructure of as-extruded Al-9.8Zn-2.0Mg-1.8Cu aluminum alloy and its evolution during solution treatment were investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), differential scanning calorimetry (DSC) analysis and electron back-scatter diffraction (EBSD). The results indicated that second phase of the as-extruded alloy mainly consisted of Mg (Zn, Cu, Al)2 and Fe-rich phases. After solution treated at 475°C for 4h, Mg (Zn, Cu, Al)2 phases were dissolved into the matrix, while Fe-rich phases still existed. Fe-rich phases cannot dissolve by prolonging solution time. The room temperature tensile strength gradually increased by prolonging solution time at 475oC. The ultimate tensile strength of the alloy reached 700MPa after both single and two-step solution treatments.

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