scholarly journals The Effect of Molybdenum on Precipitation Behaviour in Austenitic Strip-Cast Steels Containing Niobium

2020 ◽  
Author(s):  
Lu Jiang ◽  
Ross Marceau ◽  
Thomas Dorin ◽  
Huaying Yin ◽  
Xinjun Sun ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Energy Barrier ◽  
The Other ◽  
Transmission Electron ◽  
Cast Steels ◽  
Precipitation Behaviour ◽  
Strip Cast ◽  
Electron Energy Loss

Two low-C steels microalloyed with Nb were fabricated by simulated strip casting, one with Mo and the other without Mo. Both alloys were coiled at 900 °C to investigate the effect of Mo on the precipitation behaviour in austenite in low-C strip-cast Nb steels. The mechanical properties results show that during the coiling at 900 °C the hardness of both alloys increases and reaches a peak after 3000 s and then decreased after 10,000 s. Additionally, the hardness of the Mo-containing alloy is higher than that of the Mo-free alloy in all coiling conditions. Thermo-Calc predictions suggest that MC-type carbides exist in equilibrium at 900 °C, which are confirmed by transmission electron microscopy (TEM). TEM examination shows that precipitates are formed after 1000 s of coiling in both alloys and the size of the particles is refined by the addition of Mo. Energy dispersive spectroscopy (EDS) and electron energy loss spectroscopy (EELS) reveal that the carbides are enriched in Nb and N. The presence of Mo is also observed in the particles in the Nb-Mo steel during coiling. The concentration of Mo in the precipitates decreases with increasing particle size and coiling time. The precipitates in the Nb-Mo steel provide significant strengthening increments of up to 140 MPa, much higher than that in the Nb steel, ~ 96 MPa. A thermodynamic rationale is given, which explains that the enrichment of Mo in the precipitates reduces the interfacial energy between precipitates and matrix. This is likely to lower the energy barrier for their nucleation and also reduce the coarsening rate, thus leading to finer precipitates during coiling at 900 °C.

scholarly journals The Effect of Molybdenum on Precipitation Behaviour in Austenite of Strip-Cast Steels Containing Niobium

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1330
Author(s):  
Lu Jiang ◽  
Ross K. W. Marceau ◽  
Thomas Dorin ◽  
Huaying Yin ◽  
Xinjun Sun ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Energy Barrier ◽  
Isothermal Holding ◽  
The Other ◽  
Transmission Electron ◽  
Cast Steels ◽  
Heat Treated ◽  
Precipitation Behaviour ◽  
Strip Cast ◽  
Electron Energy Loss

Two low-C steels microalloyed with niobium (Nb) were fabricated by simulated strip casting, one with molybdenum (Mo) and the other without Mo. Both steels were heat treated to simulate coiling at 900 °C to investigate the effect of Mo on the precipitation behaviour in austenite in low-C strip-cast Nb steels. The mechanical properties results show that during the isothermal holding at 900 °C the hardness of both steels increases and reaches a peak after 3000 s and then decreased after 10,000 s. Additionally, the hardness of the Mo-containing steel is higher than that of the Mo-free steel in all heat-treated conditions. Thermo-Calc predictions suggest that MC-type carbides exist in equilibrium at 900 °C, which are confirmed by transmission electron microscopy (TEM). TEM examination shows that precipitates are formed after 1000 s of isothermal holding in both steels and the size of the particles is refined by the addition of Mo. Energy dispersive spectroscopy (EDS) and electron energy loss spectroscopy (EELS) reveal that the carbides are enriched in Nb and N. The presence of Mo is also observed in the particles in the Nb-Mo steel during isothermal holding at 900 °C. The concentration of Mo in the precipitates decreases with increasing particle size and isothermal holding time. The precipitates in the Nb-Mo steel provide significant strengthening increments of up to 140 MPa, higher than that in the Nb steel, ~96 MPa. A thermodynamic rationale is given, which explains that the enrichment of Mo in the precipitates reduces the interfacial energy between precipitates and matrix. This is likely to lower the energy barrier for their nucleation and also reduce the coarsening rate, thus leading to finer precipitates during isothermal holding at 900 °C.

Influence of Coiling on Microstructural Evolution and Mechanical Properties of Strip-Cast Low-Carbon Low-Niobium Steel

2016 ◽  
Vol 879 ◽  
pp. 1182-1187 ◽  
Author(s):  
Lu Jiang ◽  
Thomas Dorin ◽  
Ross Marceau ◽  
Nicole Stanford ◽  
Peter Hodgson
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Microstructural Evolution ◽  
Strong Influence ◽  
Low Carbon ◽  
Strengthening Mechanisms ◽  
Transmission Electron ◽  
Final Microstructure ◽  
Strip Cast

As-cast low-carbon low-niobium steels fabricated by direct strip casting (DSC) were treated by simulated coiling in the lab. Coiling temperatures were carefully selected: (1) 900 ̊C (in the austenite); (2) 700 ̊C (during the austenite-to-ferrite transformation); (3) 650 ̊C (in the ferrite). Optical microscopy and transmission electron microscopy were used to examine the microstructure constituents and the precipitates. Mechanical properties were evaluated by Vickers macrohardness measurements. The results show that coiling treatment has a strong influence on the final microstructure and mechanical properties, thus highlighting the necessity to carefully design the coiling treatment. In addition, the differences in hardness for the three coiling temperatures derive from a complex combination of different strengthening mechanisms.

Nonorthogonal Twining in Epitaxial SrRuO3 Thin Films Grown on (001) LaAlO3

2001 ◽  
Vol 7 (S2) ◽  
pp. 332-333
Author(s):  
W. Tian ◽  
J. C. Jiang ◽  
X. Q. Pan
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Rf Sputtering ◽  
Perovskite Oxides ◽  
The Other ◽  
Formation Mechanisms ◽  
Spatially Resolved ◽  
Transmission Electron ◽  
Electron Energy Loss

Nonorthogonal twinings have commonly been observed in perovskite oxides such as SrTi03 and BaTi03. Among them, the ﹛111﹜ Σ3 type twining exists with a relative large amount of population and has been extensively studied. By combining quantitative high resolution transmission electron microscopy (HRTEM) and spatially resolved electron energy loss spectroscopy (EELS), one was able to determine the atomic structure of the ﹛111﹜Σ3 twin boundary in these oxides.[l] On the other hand, nonorthogonal twinings in SrRuO3 have been much less studied. SrRu03, a ternary ruthenium metal oxide, has a perovskite-compatible structure and exhibits low electrical resistivity (10-4 Ω•cm), showing an unparallel technique importance in microelectronic applications. Since the properties of material strongly depend on the microstructure and defect configurations, it is important to study the twining structures and their formation mechanisms in SrRuO3 thin films.Transmission electron microscopy (TEM) was used to study the SrRuO3 thin films grown on (001) LaAlO3 by 90° off-axis rf sputtering.

The Influence of Iron on the Physical and Mechanical Properties of β-Nial

1994 ◽  
Vol 364 ◽  
Author(s):  
Y. J. Lim ◽  
K. T. Hong ◽  
V. Levit ◽  
M. J. Kaufmann
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Electrical Resistivity ◽  
Magnetic Susceptibility ◽  
Low Temperatures ◽  
Physical And Mechanical Properties ◽  
The Other ◽  
Resistivity Data ◽  
Transmission Electron

AbstractThe influence of iron on the the microstructure and properties of B2 NiAl has been investigated using electrical resistivity, magnetic susceptibility, microhardness and transmission electron microscopy. The resistivity data suggest that quenched-in vacancies (1) enhance iron rearrangement at low temperatures (600–800 K) and (2) annihilate above 800 K. These effects depend strongly on Ni/Al ratio and are greatest for Ni/Al=1. It is also shown that these data correlate directly with the results obtained using the other experimental techniques.

Phase Transformations in Ti-7w/oMo-3w/oMe Alloy

1974 ◽  
Vol 32 ◽  
pp. 514-515
Author(s):  
S. Fujishiro
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Mechanical Processing ◽  
Ray Method ◽  
X Ray ◽  
Transmission Electron ◽  
Water Quench ◽  
Alpha Beta

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.

Investigation of Switching Mechanism in HfO2-Based Oxide Resistive Memories by In-Situ Transmission Electron Microscopy and Electron Energy Loss Spectroscopy

2017 ◽  
Author(s):  
T. Dewolf ◽  
D. Cooper ◽  
N. Bernier ◽  
V. Delaye ◽  
A. Grenier ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Hafnium Dioxide ◽  
Switching Mechanism ◽  
Transmission Electron ◽  
Electron Energy Loss

Abstract Forming and breaking a nanometer-sized conductive area are commonly accepted as the physical phenomenon involved in the switching mechanism of oxide resistive random access memories (OxRRAM). This study investigates a state-of-the-art OxRRAM device by in-situ transmission electron microscopy (TEM). Combining high spatial resolution obtained with a very small probe scanned over the area of interest of the sample and chemical analyses with electron energy loss spectroscopy, the local chemical state of the device can be compared before and after applying an electrical bias. This in-situ approach allows simultaneous TEM observation and memory cell operation. After the in-situ forming, a filamentary migration of titanium within the dielectric hafnium dioxide layer has been evidenced. This migration may be at the origin of the conductive path responsible for the low and high resistive states of the memory.

Effect of Coupled Conditions of Thermal Cycle and Dump Environment on Conductivity of 5mol% Yttria Stabilized Zirconia

2013 ◽  
Vol 591 ◽  
pp. 245-248 ◽  
Author(s):  
Jin Feng Xia ◽  
Hong Qiang Nian ◽  
Tao Feng ◽  
Hai Fang Xu ◽  
Dan Yu Jiang
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
Thermal Cycle ◽  
Oxygen Sensor ◽  
Yttria Stabilized Zirconia ◽  
Cyclic Change ◽  
Stabilized Zirconia ◽  
Transmission Electron

In some applications such as automotive oxygen sensor, 5mol% Y2O3stabilized zirconia (5YSZ) is generally used because it has both excellent ionic conductivity and mechanical properties. The automotive oxygen sensor would experience a cyclic change from high temperature (engine running) environment to the low temperature damp environment (in the tail pipe when vehicle stops). The conductivity change with coupled conditions of thermal cycle and dump environment in the 5mol%Y2O3ZrO2(5YSZ) system was examined by XRD,Impedance spectroscopy and transmission electron microscopy (SEM) in this paper.

Application and Study of Reactive Polyacrylate Microgel in Pigment Paint of Printed Fabric

2011 ◽  
Vol 311-313 ◽  
pp. 1044-1048
Author(s):  
Hong Long Xing ◽  
Shui Lin Chen
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Sodium Dodecyl ◽  
Ammonium Persulfate ◽  
Color Fastness ◽  
Adhesive Film ◽  
Transmission Electron ◽  
Divinyl Benzene

Polyacrylate microgel emulsion was prepared by emulsion polymerization using styrene, α-n-butyl acrylate and methyl methacrylate as monomer, polyoxyethylene octylphenol ether (TX-30) and sodium dodecyl sulfate(SDS) as combine emulsifier, divinyl benzene and ammonium persulfate (APS) as initiator，respectively. The prepared microgel was analyzed by a variety of measurment methods, such as Fourier transform infrared spectroscopy and transmission electron microscopy. The effect of microgel on the rheological properties of adhesives, leveling, mechanical properties and pigment printing performance was studied. The rhelogy and the color fastness of the pigment printing binder of printed fabrics were measured by rheometer and friction color fastness test instruments, respectively. At the same time, the mechanical properties of the adhesive film was measured by strength tester. The results show that the thixotropy, leveling and mechanical properties of adhesive printing binder and pringting quality of coating fabrics were improved when the microgel was added.

Mechanical Properties and Microstructure Evolution of Typical Over-Aging State Al-Zn-Mg-Cu Alloy during Thermal Exposure

2021 ◽  
Vol 1026 ◽  
pp. 84-92
Author(s):  
Tao Qian Cheng ◽  
Zhi Hui Li
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Mechanical Property ◽  
Electrical Conductivity ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Thermal Exposure ◽  
Cu Alloy ◽  
Transmission Electron ◽  
Thermal Stability Of

Al-Zn-Mg-Cu alloy have been widely used in aerospace industry. However, there is still a lack of research on thermal stability of Al-Zn-Mg-Cu alloy products. In the present work, an Al-Zn-Mg-Cu alloy with T79 and T74 states was placed in the corresponding environment for thermal exposure experiments. Performance was measured by tensile strength, hardness and electrical conductivity. In this paper, precipitation observation was analyzed by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HREM). The precipitations of T79 state alloy were GPⅡ zone, η' phase and η phase while the ultimate tensile strength, hardness and electrical conductivity were 571MPa, 188.2HV and 22.2MS×m-1, respectively. The mechanical property of T79 state alloy decreased to 530MPa and 168.5HV after thermal exposure. The diameter of precipitate increased and the precipitations become η' and η phase at the same time. During the entire thermal exposure, T74 state alloy had the same mechanical property trend as T79 state alloy. The precipitate diameter also increased while the types of precipitate did not change under thermal exposure. The size of precipitates affected the choice of dislocation passing through the particles to affect the mechanical properties.

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