The effect of high-temperature and high-stress martensite aging on martensitic transformation and microstructure of Ti–51.5 at % Ni single crystals

2020 ◽  
Author(s):  
E. E. Timofeeva ◽  
E. Yu. Panchenko ◽  
A. S. Eftifeeva ◽  
E. I. Yanushonite ◽  
M. V. Zherdeva ◽  
...  
Keyword(s):  
High Temperature ◽  
Martensitic Transformation ◽  
Single Crystals ◽  
High Stress

Effect of Thermomechanical Treatment on Superelasticity in Ni54Fe19Ga27 Single Crystals

2014 ◽  
Vol 1040 ◽  
pp. 24-28
Author(s):  
Anton Tagil'tsev ◽  
Ekaterina Timofeeva ◽  
Elena Panchenko ◽  
Yuri Chumlyakov
Keyword(s):  
High Temperature ◽  
Martensitic Transformation ◽  
Single Crystals ◽  
Yield Stress ◽  
Thermomechanical Treatment ◽  
Treatment Result

In the present study the effects of thermomechanical treatment on the stress-induced martensitic transformation and superelasticity of [001]-oriented Ni54Fe19Ga27 (at.%) single crystals were investigated. It is shown that high-temperature superelasticity is observed up to 453 K in the as-grown Ni54Fe19Ga27 single crystals. Thermomechanical treatment result in increasing of the martensite yield stress, and so the SE interval, which is observed up to 523 K.

Effect of High Temperature and High Stress-Assisted Austenite Aging on Martensitic Transformations in High-Strength Ti – 51.8 ат.% Ni Single Crystals

2020 ◽  
Vol 63 (1) ◽  
pp. 126-133
Author(s):  
E. E. Timofeeva ◽  
E. Yu. Panchenko ◽  
A. I. Tagiltsev ◽  
Yu. I. Chumlyakov ◽  
M. V. Zherdeva ◽  
...  
Keyword(s):  
High Temperature ◽  
Single Crystals ◽  
High Stress ◽  
High Strength ◽  
Martensitic Transformations

Precipitation of NiHfsi phase in NiAl single crystals containing Hf

1995 ◽  
Vol 53 ◽  
pp. 532-533
Author(s):  
A. Garg ◽  
R. D. Noebe ◽  
R. Darolia
Keyword(s):  
High Temperature ◽  
Single Crystals ◽  
High Temperature Strength ◽  
Bridgman Technique ◽  
Shell Mold ◽  
Third Phase ◽  
Unknown Phase ◽  
Transmission Electron ◽  
Two Phases ◽  
Nial Matrix

Small additions of Hf to NiAl produce a significant increase in the high-temperature strength of single crystals. Hf has a very limited solubility in NiAl and in the presence of Si, results in a high density of G-phase (Ni16Hf6Si7) cuboidal precipitates and some G-platelets in a NiAl matrix. These precipitates have a F.C.C structure and nucleate on {100}NiAl planes with almost perfect coherency and a cube-on-cube orientation-relationship (O.R.). However, G-phase is metastable and after prolonged aging at high temperature dissolves at the expense of a more stable Heusler (β'-Ni2AlHf) phase. In addition to these two phases, a third phase was shown to be present in a NiAl-0.3at. % Hf alloy, but was not previously identified (Fig. 4 of ref. 2 ). In this work, we report the morphology, crystal-structure, O.R., and stability of this unknown phase, which were determined using conventional and analytical transmission electron microscopy (TEM).Single crystals of NiAl containing 0.5at. % Hf were grown by a Bridgman technique. Chemical analysis indicated that these crystals also contained Si, which was not an intentional alloying addition but was picked up from the shell mold during directional solidification.

Crystallization sequence of an A1N-Y2O3-SiO2 glass-ceramic

1986 ◽  
Vol 44 ◽  
pp. 446-447
Author(s):  
T.R. Dinger ◽  
G. Thomas
Keyword(s):  
High Temperature ◽  
Glass Ceramic ◽  
Crystallization Behavior ◽  
High Stress ◽  
Crystallization Sequence ◽  
Sio2 Glass ◽  
Structural Applications ◽  
Ceramic Precursors

The use of Si3N4, alloys for high temperature, high stress structural applications has prompted numerous studies of the oxynitride glasses which exist as intergranular phases in their microstructures. Oxynitride glasses have been investigated recently in their bulk form in order to understand their crystallization behavior for subsequent Si3N4 applications and to investigate their worth as glass-ceramic precursors. This research investigates the crystallization sequence of a glass having a normalized composition of Y26Si30Al11 ON11 and lying in the A1N-Y2O3-SiO2 section of the Y-Si-Al-O-N system. Such glasses exist as intergranular phases in the technologically important Y2O3/Al2O3-fluxed Si3N4 alloys.

Effect of Carbide Content on Temper Embrittlement of 2.25Cr1Mo Steel

2016 ◽  
Author(s):  
Yian Wang ◽  
Guoshan Xie ◽  
Zheng Zhang ◽  
Xiaolong Qian ◽  
Yufeng Zhou ◽  
...  
Keyword(s):  
High Temperature ◽  
Pressure Vessel ◽  
High Stress ◽  
Temper Embrittlement ◽  
Damage Mechanism ◽  
Pressure Vessels ◽  
Nondestructive Method ◽  
Operating Conditions ◽  
Low Alloy Steels ◽  
Carbide Content

Temper embrittlement is a common damage mechanism of pressure vessels in the chemical and petrochemical industry serviced in high temperature, which results in the reduction of roughness due to metallurgical change in some low alloy steels. Pressure vessels that are temper embrittled may be susceptible to brittle fracture under certain operating conditions which cause high stress by thermal gradients, e.g., during start-up and shutdown. 2.25Cr1-Mo steel is widely used to make hydrogenation reactor due to its superior combination of high mechanical strength, good weldability, excellent high temperature hydrogen attack (HTHA) and oxidation-resistance. However, 2.25Cr-1Mo steel is particularly susceptible to temper embrittlement. In this paper, the effect of carbide on temper embrittlement of 2.25Cr-1Mo steel was investigated. Mechanical properties and the ductile-brittle transition temperature (DBTT) of 2.25Cr-1Mo steel were measured by tensile test and impact test. The tests were performed at two positions (base metal and weld metal) and three states (original, step cooling treated and in-service for a hundred thousand hours). The content and distribution of carbides were analyzed by scanning electron microscope (SEM). The content of Cr and Mo elements in carbide was measured by energy dispersive X-ray analysis (EDS). The results showed that the embrittlement could increase the strength and reduce the plasticity. Higher carbide contents appear to be responsible for the higher DBTT. The in-service 2.25Cr-1Mo steel showed the highest DBTT and carbide content, followed by step cooling treated 2.25Cr-1Mo steel, while the as-received 2.25Cr-1Mo steel has the minimum DBTT and carbide content. At the same time, the Cr and Mo contents in carbide increased with the increasing of DBTT. It is well known that the specimen analyzed by SEM is very small in size, sampling SEM specimen is convenient and nondestructive to pressure vessel. Therefore, the relationship between DBTT and the content of carbide offers a feasible nondestructive method for quantitative measuring the temper embrittlement of 2.25Cr-1Mo steel pressure vessel.

Magnetic and superconducting properties of single crystals of Sr2HoRu1−xCuxO6 grown from high temperature solutions

2006 ◽  
Vol 89 (23) ◽  
pp. 232509 ◽  
Author(s):  
S. M. Rao ◽  
K. J. Wang ◽  
N. Y. Yen ◽  
Y. Y. Chen ◽  
C. B. Tsai ◽  
...  
Keyword(s):  
High Temperature ◽  
Single Crystals ◽  
Superconducting Properties

High temperature solution growth of perovskite Pb2CoWO6 single crystals

1991 ◽  
Vol 112 (1) ◽  
pp. 71-83 ◽  
Author(s):  
B.N. Sun ◽  
R. Boutellier ◽  
Ph. Sciau ◽  
E. Burkhardt ◽  
V. Rodriguez ◽  
...  
Keyword(s):  
High Temperature ◽  
Single Crystals ◽  
Solution Growth ◽  
High Temperature Solution ◽  
Temperature Solution
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