High Strength Mg-Zn-Y-Ce-Zr Alloy Bars Prepared by RS and Extrusion Technology

2005 ◽  
Vol 488-489 ◽  
pp. 495-498 ◽  
Author(s):  
Xuefeng Guo ◽  
Jacob Kinstler ◽  
Lilia Glazman ◽  
Dan Shechtman
Keyword(s):  
Grain Boundaries ◽  
High Strength ◽  
Submicron Particles ◽  
Commercial Alloy ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Matrix ◽  
Extrusion Technology ◽  
Scanning Electron ◽  
Zr Alloy

Based on the commercial alloy ZK60 which contains 6%Zn, high strength Mg-6.0%Zn-1.0%Y-0.6%Ce-0.6%Zr magnesium alloy bars of 10 to 50 mm in diameters were prepared by rapid solidification (RS) and extrusion processes （RSE）. For those RSE solid bars, the ultimate tensile strengths steadily maintain on a level of 490 to 520 MPa, the elongations are between 6 to 10%. The HV50 hardness is between 85 and 90. In order to reveal materials microstructures both RS ribbons and RSE solid bars, the Mg-6.0%Zn-1.0%Y-0.6%Ce-0.6%Zr alloy was analyzed with an optical microscopy (OM), a scanning electron microscopy (SEM) equipped with an energy-dispersive X-ray spectrometer (EDS) and an X-ray diffraction apparatus. It was found that the microstructure of the RS ribbon consists of super saturated (Mg) solid solution; thermally stable Mg3Y2Zn3 (W) and Mg7Ce2 intermetallic compound particles which uniformly dispersed interior grains and W and Mg7Ce2 compound networks at grain boundaries. After extrusion, the microstructure of RSE Mg-6.0%Zn-1.0%Y-0.6%Ce-0.6%Zr solid bar consists of the same phases as the RS ribbons. The networks existing at RS ribbon’s grain boundaries were break up into submicron particles and dispersed uniformly on the matrix formed after extrusion.

Characteristics of Ni–Cr–Fe laser clad layers on EA4T steel

2017 ◽  
Vol 31 (16-19) ◽  
pp. 1744031
Author(s):  
Wenjing Chen ◽  
Hui Chen ◽  
Yongjing Wang ◽  
Congchen Li ◽  
Xiaoli Wang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cladding Layer ◽  
Metallurgical Bonding ◽  
The Matrix ◽  
Feeding Speed ◽  
Upper Bainite ◽  
Scanning Electron

The Ni–Cr–Fe metal powder was deposited on EA4T steel by laser cladding technology. The microstructure and chemical composition of the cladding layer were analyzed by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The bonding ability between the cladding layer and the matrix was measured. The results showed that the bonding between the cladding layer and the EA4T steel was metallurgical bonding. The microstructure of cladding layer was composed of planar crystals, columnar crystals and dendrite, which consisted of Cr2Ni3, [Formula: see text] phase, M[Formula: see text]C6 and Ni3B phases. When the powder feeding speed reached 4 g/min, the upper bainite occurred in the heat affected zone (HAZ). Moreover, the tensile strength of the joint increased, while the yield strength and the ductility decreased.

Effect of FLiBe Infiltration Pressure on Microstructure of Matrix for TMSR Fuel Elements (FEs)

2017 ◽  
Vol 373 ◽  
pp. 189-192
Author(s):  
Hong Xia Xu ◽  
Jun Lin ◽  
Yu Chen ◽  
Bing Chuan Gu ◽  
Bang Jiao Ye ◽  
...  
Keyword(s):  
Positron Lifetime ◽  
X Ray Diffraction ◽  
X Ray ◽  
Positron Annihilation Lifetime ◽  
Infiltration Pressure ◽  
Matrix Graphite ◽  
The Matrix ◽  
Diffraction Patterns ◽  
Fuel Elements ◽  
Scanning Electron

The matrix graphite of fuel elements (FEs) with infiltration of 2LiF-BeF2(FLiBe) at different pressures varying from 0.4 MPa to 1.0 MPa, has been studied by X-ray diffraction (XRD), scanning electron microscope (SEM) and positron annihilation lifetime (PAL) measurement. The result of XRD reveals that diffraction patterns of FLiBe appear in matrix graphite infiltrated with FLiBe at a pressure of 0.8 MPa and 1.0 MPa. The surface morphology from SEM shows that FLiBe mainly distributes within macro-pores of matrix graphite. PAL measurement indicates that there are mainly two positron lifetime components in all specimens:τ1~0.21 ns and τ2 ­~0.47 ns, ascribed to annihilation of positrons in bulk and trapped-positrons at surface, respectively. The average positron lifetime decreases with infiltration pressure, due to the decrease in annihilation fraction of positrons with surface after infiltration of FLiBe into macro-pores.

scholarly journals Effect of CNT Contents on the Microstructure and Properties of CNT/TiMg Composites

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1620
Author(s):  
Xiaomin Yuan ◽  
Haonan Zhu ◽  
Huiling Ji ◽  
Yiwei Zhang
Keyword(s):  
Cross Section ◽  
Optical Microscope ◽  
Solution Phase ◽  
Solid Solution Phase ◽  
Wet Milling ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microstructure Observation ◽  
The Matrix ◽  
Scanning Electron

Carbon nanotubes (CNTs), dispersed in absolute ethanol, were evenly mixed into Ti/MgH2 powders by wet milling. Then, we applied the vacuum hot-pressed sinteringmethod to the CNTs/TiMg composite materials. An optical microscope (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and a field emission scanning electron microscope (FESEM) were used for the microstructure observation and phase analysis of samples. The mechanical properties were measured via the micro-vickers hardness. The results show that the main phases in the composites were Ti, Mg and C. Meanwhile, a small amount of Ti-Mg solid solution phase was also found. The cross-section morphology of the composites shows that the melted magnesium fills the grain interface during extrusion and that the composites have a better compactness.The microstructures of the composites have been greatly refined as the CNT contents increased. The structure of the composites was further refined when 0.5 wt.% CNTs were added. The fracture surface is obviously a ductile fracture. The microhardness increases obviously with the CNT content increasing. When the content of the CNTs is 1.0 wt.%, the microhardness of the composites reaches 232 HV, which is 24% higher than that of the matrix.

Fabrication of TiAl/Ti2AlC Composite by Reaction Hot Pressing

2011 ◽  
Vol 52-54 ◽  
pp. 842-845 ◽  
Author(s):  
Jian Feng Zhu ◽  
Wen Wen Yang ◽  
Yi Ping Gong
Keyword(s):  
Electron Microscopy ◽  
Reaction Process ◽  
Hot Press ◽  
X Ray Diffraction ◽  
X Ray ◽  
In Situ Composite ◽  
The Matrix ◽  
Morphology Characteristics ◽  
Scanning Electron

TiAl/Ti2AlC in situ composite was successfully fabricated by hot-press-assisted reaction process from the mixture of Ti, Al and carbon black. The phase formation and transformation were investigated in detail by X-ray diffraction (XRD) and the morphology characteristics were also studied by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that when the mixed powders were hot pressed at 1300 °C for 1 h, full dense and highly pure TiAl/Ti2AlC composite was synthesized. The TiAl was the matrix phase and the in situ synthesized Ti2AlC was reinforcing phase. The reaction process was also discussed.

Influence of Annealing Time on Microstructure of Ni-W Alloys

2013 ◽  
Vol 747-748 ◽  
pp. 613-618
Author(s):  
Qiao Zhang ◽  
Shu Hua Liang ◽  
Chen Zhang ◽  
Jun Tao Zou
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Grain Size ◽  
Grain Boundaries ◽  
Annealing Time ◽  
Single Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Average Grain Size ◽  
Scanning Electron

The as-cast Ni-W alloys with 15wt%W, 25wt%W and 30wt%W were annealed in hydrogen at 1100. The effect of the annealing time on the microstructure of Ni-W alloys was studied, and the phase constituents and microstructure of annealed Ni-W alloys were characterized by the X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that no any phase changed for Ni-15%W, Ni-25%W and Ni-30%W alloys annealed for 60 min, 90 min and 150 min, which were still consisted of single-phase Ni (W) solid solution. However, microstructure had a significant change after annealing. With increase of annealing time, the microstructure of Ni-15%W alloy became more uniform after annealing for 90 min, and the average grain size was 95μm, whereas the grain size of Ni-15%W alloy increased significantly after annealing for 150 min. For Ni-25%W and Ni-30%W, there was no obvious change on the grain size with increase of annealing time, and the amount of oxides at grain boundaries gradually reduced. After annealing for 150 min, the impurities at grain boundaries almost disappeared. Subsequently, the annealing at 1100 for 150 min was beneficial for the desired microstructure of Ni-25%W and Ni-30%W alloys.

Powder characteristics and sintering behavior of Ag-doped YBa2Cu3O7−x produced by aerosol decomposition

1992 ◽  
Vol 7 (4) ◽  
pp. 827-836 ◽  
Author(s):  
Timothy L. Ward ◽  
Toivo T. Kodas ◽  
Altaf H. Carim ◽  
Donald M. Kroeger ◽  
Huey Hsu
Keyword(s):  
Submicron Particles ◽  
Sintering Behavior ◽  
X Ray Diffraction ◽  
Powder Synthesis ◽  
X Ray ◽  
Grain Sizes ◽  
Powder Characteristics ◽  
Scanning Electron ◽  
Nitrate Solutions ◽  
Reaction Routes

YBa2Cu3O7−x (1-2-3) powders and 1-2-3 powders doped with 14 wt. % Ag (AgYBa2Cu3O7−x) were produced using aerosol decomposition of nitrate solutions. Powder produced at T > 900 °C consisted of submicron particles and had Tc ≍ 92 K in magnetic susceptibility measurements. As-produced Ag-doped powder was a composite of nearly phase-pure 1-2-3 and crystalline Ag (by x-ray diffraction) for reactor temperatures between 900 °C and 950 °C, whereas powder produced at T≥ 970 °C contained significant amounts of Y2BaCuO5 which were not found in 1-2-3 synthesis in the absence of Ag. This implied that the melting of Ag (∼960 °C) or the Ag-O eutectic (∼940 °C) promoted decomposition of 1-2-3 during powder synthesis. Dilatometry showed that 1-2-3 and Ag/1-2-3 powders densified rapidly between 800 °C and 875 °C, achieving nearly 90% of theoretical density after heating to 875 °C at 5 °C/min in air. Pellets of the Ag-doped powder were also sintered for 2-60 h at 895 °C in air. Scanning electron and optical microscopy revealed that Ag grains remained fine and uniformly distributed, varying in size from ∼1 μm after 2 h to 3–7 μm after 60 h, while 1-2-3 grains became plate-shaped with thicknesses of 1–5 μm and lengths of 10–30 μm after 60 h. Thus, the use of aerosol Ag /1-2-3 powders allows the use of lower processing temperatures and shorter times to produce dense ceramics with smaller Ag and 1-2-3 grain sizes than can be obtained using solid-state reaction routes.

Experimental Research on High-Strength Super Sulphate Cement Paste Mixed with Superfine Mineral Admixtures

2014 ◽  
Vol 629-630 ◽  
pp. 150-155
Author(s):  
Jun Wang ◽  
Bao Ying Yu ◽  
Long Yang ◽  
Yu Xin Gao ◽  
Jia Yu Xiang
Keyword(s):  
Silica Fume ◽  
High Strength ◽  
Hydration Product ◽  
Mineral Admixtures ◽  
Hydration Reaction ◽  
X Ray Diffraction ◽  
Cement Ratio ◽  
X Ray ◽  
Early Strength ◽  
Scanning Electron

Aimed at the performance affect of high-strength super sulphate cement (SSC) paste mixed with superfine mineral admixtures, influence of microbead and silica fume replacing SSC quantity on high-strength SSC paste compression strength were studied under water-cement ratio 0.18; Hydration product morphology and phase were further compared by scanning electron microscopy and X-ray diffraction analyzer in this paper. Results show that, compared with sample HS-1, 3-day strength of HS-2 and HS-3 were increased by 5% and 10%, 28d strength basically unchanged; Furthermore, early strength of HS-7 sample slightly higher and late strength basically unchanged. SSC by adding 5% microbead and 3% silica fume (HS-11) has compressive strength 50.8MPa at 3 days and 86.1MPa at 28 days is significantly higher than other samples. Early strength of HS-11sample mainly depends on hydration reaction of SSC and particle filling effect of admixtures, later strength is due to accelerating consumption of gypsum and promoting formation of ettringite.

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 Enhancing the Oxidation Resistance of Al2O3-SiC-C Castables via Introducing Micronized Andalusite

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4775 ◽  
Author(s):  
Xiaoyu Wang ◽  
Saixin Wang ◽  
Yuandong Mu ◽  
Ruijie Zhao ◽  
Qingfeng Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Oxygen Diffusion ◽  
Area Ratio ◽  
Modulus Of Rupture ◽  
Thermal Shock Test ◽  
X Ray Diffraction ◽  
Shock Test ◽  
X Ray ◽  
The Matrix ◽  
Scanning Electron

Additions of andalusite aggregates (19 wt%) were shown in previous literature to enhance the antioxidation of Al2O3-SiC-C (ASC) castables. This work aims to investigate whether micronized andalusite has a greater influence on antioxidation improvement than andalusite aggregates. Various low contents (5 wt% and below) of micronized andalusite (≤5 μm) were introduced as a substitute for brown fused alumina in the matrix of ASC castables. The antioxidation of castable specimens was estimated by the oxidized area ratio on the fracture surface after a thermal shock test. The microstructure and phases of micronized andalusite and the castable specimens were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The results suggest that the antioxidation effects of ASC castables with a low addition of micronized andalusite are effectively enhanced. The heat-induced transformation of andalusite produces SiO2-rich glass, favoring the sintering of the castable matrix and impeding oxygen diffusion into the castable’s interior. Therefore, the castable antioxidation is enhanced without deteriorating the hot modulus of rupture.

scholarly journals Evolution of Free Volumes in Polycrystalline BaGa2O4 Ceramics Doped with Eu3+ Ions

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1515
Author(s):  
Halyna Klym ◽  
Ivan Karbovnyk ◽  
Andriy Luchechko ◽  
Yuriy Kostiv ◽  
Viktorija Pankratova ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Phase Composition ◽  
Grain Boundaries ◽  
Solid Phase ◽  
X Ray Diffraction ◽  
Spectroscopy Technique ◽  
X Ray ◽  
Positron Annihilation Lifetime ◽  
Scanning Electron

BaGa2O4 ceramics doped with Eu3+ ions (1, 3 and 4 mol.%) were obtained by solid-phase sintering. The phase composition and microstructural features of ceramics were investigated using X-ray diffraction and scanning electron microscopy in comparison with energy-dispersive methods. Here, it is shown that undoped and Eu3+-doped BaGa2O4 ceramics are characterized by a developed structure of grains, grain boundaries and pores. Additional phases are mainly localized near grain boundaries creating additional defects. The evolution of defect-related extended free volumes in BaGa2O4 ceramics due to the increase in the content of Eu3+ ions was studied using the positron annihilation lifetime spectroscopy technique. It is established that the increase in the number of Eu3+ ions in the basic BaGa2O4 matrix leads to the agglomeration of free-volume defects with their subsequent fragmentation. The presence of Eu3+ ions results in the expansion of nanosized pores and an increase in their number with their future fragmentation.

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