Grain-Coarsening Resistance and the Stability of Second-Phase Dispersions in Rapidly Solidified Steels

1981 ◽  
Author(s):  
G. B. Olson ◽  
H. C. Ling ◽  
J. S. Montgomery ◽  
J. B. Vander Sande ◽  
M. Cohen
Keyword(s):  
Second Phase ◽  
Grain Coarsening ◽  
The Stability ◽  
Rapidly Solidified

Grain-Coarsening Resistance and The Stability of Second-Phase Dispersions in Rapidly Solidified Steels

1981 ◽  
Vol 8 ◽  
Author(s):  
G. B. Olson ◽  
H. C. Ling ◽  
J. S. Montgomery ◽  
J. B. Vander Sande ◽  
M. Cohen
Keyword(s):  
Rare Earth ◽  
Grain Boundary ◽  
Alloy Composition ◽  
Second Phase ◽  
Alloy Development ◽  
Grain Coarsening ◽  
Dispersed Phases ◽  
Grain Boundary Pinning ◽  
The Stability ◽  
Rapidly Solidified

ABSTRACTControl of alloy composition and processing to achieve grain coarsening resistance in rapidly solidified alloys is examined via the theory of grain boundary pinning and particle coarsening. The principles are illustrated for the case of manganese sulfides in steels. A thermodynamic survey of potential stable dispersed phases identifies TiN and rare-earth sulfides as particularly promising for alloy development via rapid solidification.

Oxide Dispersions in Rapidly Solidified Ti Alloys

1983 ◽  
Vol 28 ◽  
Author(s):  
D.G. Konitzer ◽  
R. Kirchheim ◽  
H.L. Fraser
Keyword(s):  
Heat Treatment ◽  
Rare Earth ◽  
Rare Earth Oxide ◽  
Rapid Solidification Processing ◽  
Laser Surface ◽  
Second Phase ◽  
Solidification Processing ◽  
Ti Alloys ◽  
The Stability ◽  
Rapidly Solidified

ABSTRACTTechniques of rapid solidification processing were used to refine a dispersion of rare earth oxides in Ti. The dispersion was produced by laser surface melting and subsequent heat treatment of a Ti-Er alloy. The second phase was identified as the rare earth oxide. The stability of the dispersion was investigated analytically and experimentally and the correlation between the analysis and experiments was shown to be very good.

An analysis of the transport properties and mechanical stability of rapidly solidified Al-Sb alloy

2015 ◽  
Vol 10 (2) ◽  
pp. 2663-2681
Author(s):  
Rizk El- Sayed ◽  
Mustafa Kamal ◽  
Abu-Bakr El-Bediwi ◽  
Qutaiba Rasheed Solaiman
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Melt Spinning ◽  
Elastic Moduli ◽  
Mechanical Stability ◽  
Microstructural Analysis ◽  
Alloy System ◽  
Antimony Content ◽  
The Stability ◽  
Rapidly Solidified

The structure of a series of AlSb alloys prepared by melt spinning have been studied in the as melt–spun ribbons  as a function of antimony content .The stability  of these structures has  been  related to that of the transport and mechanical properties of the alloy ribbons. Microstructural analysis was performed and it was found that only Al and AlSb phases formed for different composition.  The electrical, thermal and the stability of the mechanical properties are related indirectly through the influence of the antimony content. The results are interpreted in terms of the phase change occurring to alloy system. Electrical resistivity, thermal conductivity, elastic moduli and the values of microhardness are found to be more sensitive than the internal friction to the phase changes. 

Stability-Guaranteed Two-Phase Design of Odd-Order Variable-Magnitude Digital Filters

2016 ◽  
Vol 26 (02) ◽  
pp. 1750033
Author(s):  
Tian-Bo Deng
Keyword(s):  
Transfer Function ◽  
Digital Filter ◽  
Digital Filters ◽  
Tuning Parameter ◽  
Second Phase ◽  
Variable Model ◽  
Odd Order ◽  
Order Variable ◽  
The Stability ◽  
Fifth Order

Guaranteeing the stability is one of the most critical issues in designing a variable recursive digital filter. In this paper, we first present an odd-order recursive variable model (transfer function) that is used for designing an odd-order variable-magnitude (VM) digital filter, and then we replace the original coefficients of the denominator of the odd-order transfer function with a set of new parameters. These new parameters can ensure that they can take arbitrary values without incurring instability of the designed odd-order VM filter. To make the VM filter coefficients variable, we find all the VM filter coefficients as polynomial functions of the tuning parameter, which includes two phases. The first phase designs a set of recursive digital filters with fixed coefficients (constant filters), and the second phase utilizes a curve-fitting scheme to represent each coefficient as a polynomial function. As a result, the VM filter coefficients become variable, and the proposed parameter-substitution-based denominator coefficients ensure the filter stability. This is the most important contribution of the parameter-substitution-based design scheme. This paper uses the fifth-order demonstrative example to verify the stability guarantee as well as the design accuracy of the obtained the fifth-order VM filter.

Microstructural Instability in Mosi2/Sic Nanolayers

1997 ◽  
Vol 3 (S2) ◽  
pp. 399-400
Author(s):  
Y.C. Lu ◽  
H. Kung ◽  
J-P Hirvonen ◽  
T.R. Jervis ◽  
M. Nastasi ◽  
...  
Keyword(s):  
High Temperature ◽  
Ion Irradiation ◽  
High Temperature Strength ◽  
Second Phase ◽  
Microstructural Stability ◽  
Factors Affecting ◽  
Structural Applications ◽  
Thermal Compatibility ◽  
Two Phases ◽  
The Stability

Thin film multilayers have been the focus of extensive studies recently due to the interesting properties they exhibit. Since the improvement in properties can be attributed directly to the unique nanoscale microstructures, it is essential to understand the factors affecting the microstructural stability in these nanolayer structures. The intermetallic compound, MoSi2, despite its superior oxidation resistance and high melting point, suffers from inadequate high temperature strength and low temperature ductility, properties which hinder its high temperature structural applications [1]. SiC is a potential second phase reinforcement due to its high temperature strength and thermal compatibility with MoSi2. The addition of SiC in a nanolayered configuration has been shown to exhibit significant increase in hardness after annealing [2]. It has also been shown that when annealed above 900°C, the layers break down and grain growth sets in, with a significant decrease in hardness and. Due to the lack of a thermochemical driving force, the two phases remain separate at all temperatures investigated. In this study, the stability of the MoSi2/SiC nanolayers structure under ion irradiation has been investigated.

Microstructure and Properties of Rapidly Solidified Al-Zn-Mg-Cu Alloy

2020 ◽  
Vol 993 ◽  
pp. 203-207
Author(s):  
Wei Min Ren ◽  
Zi Yong Chen ◽  
Zhi Lei Xiang ◽  
Li Hua Chai
Keyword(s):  
Aluminum Alloy ◽  
Aluminum Alloys ◽  
Cooling Rate ◽  
Rapid Solidification ◽  
Second Phase ◽  
Alloy Strip ◽  
Roller Speed ◽  
Microstructure And Properties ◽  
Cu Alloy ◽  
Rapidly Solidified

Refining grain plays an important role in improving the mechanical properties of aluminum alloys. However, the conventional casting method with a slow cooling rate can be easy to cause coarseness of the microstructure and serious segregation. In this paper, the rapid solidification of Al-Zn-Mg-Cu alloy was prepared by the single-roller belt method. The alloy strip was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and hardness test to study the microstructure and properties of the rapidly solidified aluminum alloy. The results show that the roller speed was an important parameters affecting the formability of the alloy. When the roller speed was 15 m/s, the aluminum alloy produced a thin bandwidth of 5 mm and a thickness of 150 um. As the rotation speed of the roller increased, the cooling rate of the melt increased, and the microstructure of the rapidly solidified Al-Zn-Mg-Cu aluminum alloy strip improved in grains refinement. Compared with the conventionally cast Al-Zn-Mg-Cu aluminum alloys, the Al-Zn-Mg-Cu aluminum alloys prepared by rapid solidification showed much finer crystal grains, and enhanced solid solubility of alloying elements with less precipitation of second phase and high hardness.

scholarly journals Effect of CO2 on the processing of Y–Ba–Cu–O superconductors

1992 ◽  
Vol 7 (2) ◽  
pp. 283-291 ◽  
Author(s):  
G. Selvaduray ◽  
C. Zhang ◽  
U. Balachandran ◽  
Y. Gao ◽  
K.L. Merkle ◽  
...  
Keyword(s):  
Thin Layer ◽  
Grain Boundaries ◽  
Stability Region ◽  
Gas Mixtures ◽  
Grain Structure ◽  
Second Phase ◽  
Superconducting Properties ◽  
Different Temperatures ◽  
The Stability

The superconducting properties of YBa2Cu3O6+x reacted with various known ratios of O2/CO2 gas mixtures during sintering at different temperatures were studied. Jc was found to decrease drastically upon reaction with CO2, becoming zero at certain CO2 activities. The stability region for the 123 superconductor, as a function of CO2 activity and temperature, was empirically formulated as follows: log pCO2 < (−45,000)/T + 33.4. The grain boundaries in sintered samples with Jc = 0 were investigated with HRTEM in conjunction with EDS. Two distinct types of grain boundaries were observed. Approximately 10% of the grain boundaries were wet by a thin layer of a second phase, deduced to be BaCuO2. The remaining boundaries were sharp grain boundaries. The grain structure near the sharp grain boundaries was tetragonal. These two types of grain boundaries are thought to be responsible for Jc being zero.

Étude de la pénétrabilité du coulis de ciment microfin sous pression dans les structures de maçonnerie dégradées à caractère historique : effet d'un agent colloïdal

2000 ◽  
Vol 27 (4) ◽  
pp. 642-654 ◽  
Author(s):  
Danielle Palardy ◽  
Stéphanie Perret ◽  
Gérard Ballivy ◽  
Robert Laporte
Keyword(s):  
Structural Integrity ◽  
Cement Grout ◽  
Public Works ◽  
Second Phase ◽  
Masonry Structures ◽  
Flow Rates ◽  
The Past ◽  
Microfine Cement ◽  
The Stability ◽  
Rideau Canal

Several masonry structures, built over the past centuries, have to be restored to ensure their structural integrity and their conservation. Important research and development projects have been initiated by Public Works and Government Services Canada to rehabilitate some of these structures, such as the Rideau canal locks, by using a cement-based grouting technique. By following grouting pressures and flow rates, the stability of the structure is protected and the efficiency to fill openings is assured by using microfine cement-based grouts with admixtures. However, cement grout penetration cannot be observed with precision during the injection. The project described in this paper presents the grouting treatment of a Rideau canal lock sill wall that had to be demolished and reconstructed. The penetration of two different grout mixes was observed by removing the front row of blocks, piece by piece. A second phase of this study was conducted in the laboratory to compare the penetration of different grouts in a reconstructed granular material which simulated the lock's interior walls.Key words: restoration, masonry, grouting, groutability, cement grout, colloidal agent.

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