A microstructural investigation of a Na2SO4 activated cement-slag blend

2021 ◽  
Vol 150 ◽  
pp. 106609
Author(s):  
Jiayi Fu ◽  
Mark W. Bligh ◽  
Igor Shikhov ◽  
Adele M. Jones ◽  
Camille Holt ◽  
...  
Keyword(s):  
Microstructural Investigation

Microstructural investigation of surface roughness in MBE-grown AlAs

1995 ◽  
Vol 53 ◽  
pp. 454-455
Author(s):  
R. Rajesh ◽  
R. Droopad ◽  
C. H. Kuo ◽  
R. W. Carpenter ◽  
G. N. Maracas
Keyword(s):  
Thin Film ◽  
Real Time ◽  
Growth Control ◽  
Native Oxide ◽  
Effusion Cell ◽  
Surface Oxide Layer ◽  
Microstructural Investigation ◽  
Mbe Growth ◽  
Film Substrate ◽  
And Control

Knowledge of material pseudodielectric functions at MBE growth temperatures is essential for achieving in-situ, real time growth control. This allows us to accurately monitor and control thicknesses of the layers during growth. Undesired effusion cell temperature fluctuations during growth can thus be compensated for in real-time by spectroscopic ellipsometry. The accuracy in determining pseudodielectric functions is increased if one does not require applying a structure model to correct for the presence of an unknown surface layer such as a native oxide. Performing these measurements in an MBE reactor on as-grown material gives us this advantage. Thus, a simple three phase model (vacuum/thin film/substrate) can be used to obtain thin film data without uncertainties arising from a surface oxide layer of unknown composition and temperature dependence.In this study, we obtain the pseudodielectric functions of MBE-grown AlAs from growth temperature (650°C) to room temperature (30°C). The profile of the wavelength-dependent function from the ellipsometry data indicated a rough surface after growth of 0.5 μm of AlAs at a substrate temperature of 600°C, which is typical for MBE-growth of GaAs.

scholarly journals Characterization of Al2O3 Samples and NiAl–Al2O3 Composite Consolidated by Pulse Plasma Sintering

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3398
Author(s):  
Katarzyna Konopka ◽  
Marek Krasnowski ◽  
Justyna Zygmuntowicz ◽  
Konrad Cymerman ◽  
Marcin Wachowski ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Mechanical Alloying ◽  
Ceramic Composites ◽  
Pulse Plasma ◽  
High Plasticity ◽  
Composite Powders ◽  
Microstructural Investigation ◽  
Al2o3 Powder ◽  
Plasma Sintering ◽  
Pulse Plasma Sintering

The paper describes an investigation of Al2O3 samples and NiAl–Al2O3 composites consolidated by pulse plasma sintering (PPS). In the experiment, several methods were used to determine the properties and microstructure of the raw Al2O3 powder, NiAl–Al2O3 powder after mechanical alloying, and samples obtained via the PPS. The microstructural investigation of the alumina and composite properties involves scanning electron microscopy (SEM) analysis and X-ray diffraction (XRD). The relative densities were investigated with helium pycnometer and Archimedes method measurements. Microhardness analysis with fracture toughness (KIC) measures was applied to estimate the mechanical properties of the investigated materials. Using the PPS technique allows the production of bulk Al2O3 samples and intermetallic ceramic composites from the NiAl–Al2O3 system. To produce by PPS method the NiAl–Al2O3 bulk materials initially, the composite powder NiAl–Al2O3 was obtained by mechanical alloying. As initial powders, Ni, Al, and Al2O3 were used. After the PPS process, the final composite materials consist of two phases: Al2O3 located within the NiAl matrix. The intermetallic ceramic composites have relative densities: for composites with 10 wt.% Al2O3 97.9% and samples containing 20 wt.% Al2O3 close to 100%. The hardness of both composites is equal to 5.8 GPa. Moreover, after PPS consolidation, NiAl–Al2O3 composites were characterized by high plasticity. The presented results are promising for the subsequent study of consolidation composite NiAl–Al2O3 powder with various initial contributions of ceramics (Al2O3) and a mixture of intermetallic–ceramic composite powders with the addition of ceramics to fabricate composites with complex microstructures and properties. In composites with complex microstructures that belong to the new class of composites, in particular, the synergistic effect of various mechanisms of improving the fracture toughness will be operated.

scholarly journals Microstructural Investigation of a Friction-Welded 316L Stainless Steel with Ultrafine-Grained Structure Obtained by Hydrostatic Extrusion

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1537
Author(s):  
Beata Skowrońska ◽  
Tomasz Chmielewski ◽  
Mariusz Kulczyk ◽  
Jacek Skiba ◽  
Sylwia Przybysz
Keyword(s):  
Stainless Steel ◽  
Electron Microscope ◽  
Friction Welding ◽  
High Speed ◽  
316L Stainless Steel ◽  
Welded Joint ◽  
Microstructural Investigation ◽  
Ultrafine Grained Structure ◽  
Ultrafine Grained ◽  
Friction Joint

The paper presents the microstructural investigation of a friction-welded joint made of 316L stainless steel with an ultrafine-grained structure obtained by hydrostatic extrusion (HE). Such a plastically deformed material is characterized by a metastable state of energy equilibrium, increasing, among others, its sensitivity to high temperatures. This feature makes it difficult to weld ultra-fine-grained metals without losing their high mechanical properties. The use of high-speed friction welding and a friction time of <1 s reduced the scale of the weakening of the friction joint in relation to result obtained in conventional rotary friction welding. The study of changes in the microstructure of individual zones of the friction joint was carried out on an optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and electron backscattered diffraction (EBSD) analysis system. The correlation between the microstructure and hardness of the friction joint is also presented. The heat released during the high-speed friction welding initiated the process of dynamic recrystallization (DRX) of single grains in the heat-affected zone (HAZ). The additional occurrence of strong plastic deformations (in HAZ) during flash formation and internal friction (in the friction weld and high-temperature HAZ) contributed to the formation of a highly deformed microstructure with numerous sub-grains. The zones with a microstructure other than the base material were characterized by lower hardness. Due to the complexity of the microstructure and its multifactorial impact on the properties of the friction-welded joint, strength should be the criterion for assessing the properties of the joint.

Microstructural investigation of slag-blended UHPC: The effects of slag content and chemical/thermal activation

2021 ◽  
Vol 292 ◽  
pp. 123455
Author(s):  
Omar M. Abdulkareem ◽  
Amor Ben Fraj ◽  
Marwen Bouasker ◽  
Lahcen Khouchaf ◽  
Abdelhafid Khelidj
Keyword(s):  
Thermal Activation ◽  
Microstructural Investigation ◽  
Slag Content

Deformation and Fracture Behaviors in the Freestanding APS-TBC - Effects of Process Parameters and Thermal Exposure

2007 ◽  
Vol 353-358 ◽  
pp. 1935-1938 ◽  
Author(s):  
Yasuhiro Yamazaki ◽  
T. Kinebuchi ◽  
H. Fukanuma ◽  
N. Ohno ◽  
K. Kaise
Keyword(s):  
Mechanical Properties ◽  
Process Parameters ◽  
Gas Turbines ◽  
Thermal Exposure ◽  
Substrate Material ◽  
Process Variables ◽  
Microstructural Investigation ◽  
Deformation And Fracture ◽  
Industrial Gas Turbines ◽  
Tbc Systems

Thermal barrier coatings (TBCs), that reduce the temperature in the underlying substrate material, are an essential requirement for the hot section components of industrial gas turbines. Recently, in order to take full advantage of the potential of the TBC systems, experimental and analytical investigations in TBC systems have been performed. However there is a little information on the deformation behavior of the top coating. In addition, the effects of the thermal exposure and the process parameters on the mechanical properties of the top coating have never been clarified. From these backgrounds, the effects of the process variables in APS and the thermal exposure on the mechanical properties were investigated in order to optimize the APS process of top coatings. The experimental results indicated that the mechanical properties of the APS-TBC, i.e. the tensile strength and the elastic modulus, were significantly changed by the process variables and the long term thermal exposure. The microstructural investigation was also carried out and the relationship between the mechanical properties and the porosity was discussed.

Microstructural changes in soft quick clay at failure

1970 ◽  
Vol 7 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Roland Pusch
Keyword(s):  
Shear Deformation ◽  
Shear Zone ◽  
Residual Strength ◽  
Rigid Bodies ◽  
Compression Tests ◽  
Unconfined Compression ◽  
Shear Forces ◽  
Microstructural Investigation ◽  
Shear Process ◽  
Quick Clay

A series of unconfined compression tests has been made on a marine, quick clay and small specimens were extracted for microstructural investigation. The natural microstructural pattern was characterized by a network of small aggregates connected by links of particles. The links broke down successively at increasing shear deformation and formed domain-like groups of particles. In the macroscopic shear zone the shear forces tended to orient and deform the aggregates.The aggregates behaved as rigid bodies to a certain stress level during the shear process. The concept of residual strength may correspond to the state where the majority of the links have been broken while the aggregates are still intact.

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