The Effects of Substitutional Additions on Tensile Behavior of Nb-Silicide Based Composites

2004 ◽  
Vol 842 ◽  
Author(s):  
Laurent Cretegny ◽  
Bernard P. Bewlay ◽  
Ann M. Ritter ◽  
Melvin R. Jackson
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
Room Temperature ◽  
High Strength ◽  
Aircraft Engine ◽  
Tensile Behavior ◽  
Strengthening Mechanisms ◽  
Temperature Capability ◽  
High Temperature Tensile

ABSTRACTNb-silicide based in-situ composites consist of a ductile Nb-based solid solution with high-strength silicides, and they show excellent promise for aircraft engine applications. The Nb-silicide controls the high-temperature tensile behavior of the composite, and the Nb solid solution controls the low and intermediate temperature capability. The aim of the present study was to understand the effects of substitutional elements on the room temperature tensile behavior and identify the principal microstructural features contributing to strengthening mechanisms.

Analyses of Eutectoid Phase Transformations in Nb–SilicideIn SituComposites

2004 ◽  
Vol 10 (4) ◽  
pp. 470-480 ◽  
Author(s):  
B.P. Bewlay ◽  
S.D. Sitzman ◽  
L.N. Brewer ◽  
M.R. Jackson
Keyword(s):  
Crystal Structure ◽  
Phase Transformation ◽  
High Temperature ◽  
Room Temperature ◽  
Bulk Composition ◽  
High Strength ◽  
Eutectoid Decomposition ◽  
Quaternary Alloys ◽  
Temperature Fracture

Nb–silicide in situ composites have great potential for high-temperature turbine applications. Nb–silicide composites consist of a ductile Nb-based solid solution together with high-strength silicides, such as Nb5Si3and Nb3Si. With the appropriate addition of alloying elements, such as Ti, Hf, Cr, and Al, it is possible to achieve a promising balance of room-temperature fracture toughness, high-temperature creep performance, and oxidation resistance. In Nb–silicide composites generated from metal-rich binary Nb-Si alloys, Nb3Si is unstable and experiences eutectoid decomposition to Nb and Nb5Si3. At high Ti concentrations, Nb3Si is stabilized to room temperature, and the eutectoid decomposition is suppressed. However, the effect of both Ti and Hf additions in quaternary alloys has not been investigated previously. The present article describes the discovery of a low-temperature eutectoid phase transformation during which (Nb)3Si decomposes into (Nb) and (Nb)5Si3, where the (Nb)5Si3possesses the hP16 crystal structure, as opposed to the tI32 crystal structure observed in binary Nb5Si3. The Ti and Hf concentrations were adjusted over the ranges of 21 to 33 (at.%) and 7.5 to 33 (at.%) to understand the effect of bulk composition on the phases present and the eutectoid phase transformation.

Tough, Ductile High-Temperature Intermetallic Compounds: Results of a Four-Year Survey.

1990 ◽  
Vol 213 ◽  
Author(s):  
R.L. Fleischer ◽  
C.L. Briant ◽  
R.D. Field
Keyword(s):  
High Temperature ◽  
Intermetallic Compounds ◽  
Room Temperature ◽  
Impact Resistance ◽  
High Strength ◽  
Aircraft Engine ◽  
High Temperature Strength ◽  
Beneficial Effects ◽  
Strength And Stiffness ◽  
Binary Compounds

ABSTRACTA four-year survey of high-temperature intermetallic compounds has been aimed at identifying potentially useful structural materials for aerospace and aircraft engine applications. Since the good properties of high strength and stiffness at high temperatures are typically negated by brittleness at ambient temperature, new materials must have roomtemperature toughness or ductility. Screening has been done of 90 binary compounds with 20 different crystal structures, and 130 ternary or higher-order alloys. Testing typically included hardness vs. temperature, elastic modulus determination, and toughness evaluation via a room-temperature chisel test. Four alloy systems, including only two types that are of the simplest structures, showed substantial room-temperature toughness: Al-Ru, Ru-Sc, Ir-Nb, and Ru-Ta. Of these the last and the first are the most promising. Special features of the Ru- Ta (L1o) alloys are their room-temperature impact resistance and high-temperature strength. AIRu (B2) alloys can be tougher than the L1o structures and most are also ductile in compression at room temperature. Alloying experiments with B, Cr, and Sc show beneficial effects on ductility, oxidation resistance, and high-temperature strength.

Creep Studies of Monolithic Phases in Nb-Silicide Based In-Situ Composites

2000 ◽  
Vol 646 ◽  
Author(s):  
B.P. Bewlay ◽  
C.L. Briant ◽  
E.T. Sylven ◽  
M.R. Jackson ◽  
G. Xiao
Keyword(s):  
Solid Solution ◽  
Creep Rate ◽  
Creep Resistance ◽  
High Strength ◽  
Aircraft Engine ◽  
Great Promise ◽  
In Situ Composites ◽  
Monolithic Phases ◽  
The Individual

ABSTRACTNb-silicide composites combine a ductile Nb-based solid solution with high-strength silicides, and they show great promise for aircraft engine applications. Previous work has shown that the silicide composition has an important effect on the creep rate. If the Nb:(Hf+Ti) ratio is reduced below ∼1.5, the creep rate increases significantly. This observation could be related to the type of silicide present in the material. To understand the effect of each phase on the composite creep resistance, the creep rates of selected monolithic phases were determined. To pursue this goal, monolithic alloys with compositions similar to the Nb-based solid solution and to the silicide phases, Laves, and T2 phases, were prepared. The creep rates were measured under compression at 1100 and 1200°C. The stress sensitivities of the creep rates of the monolithic phases were also determined. These results allow quantification of the load bearing capability of the individual phases in the Nb-silicide based in-situ composites.

The microstructure and crystallography of the Cr-Cr3Si eutectic

1991 ◽  
Vol 49 ◽  
pp. 598-599
Author(s):  
J.A. Sutlif ◽  
B.P. Bewlay ◽  
K.M. Chang ◽  
M.R. Jackson
Keyword(s):  
High Temperature ◽  
High Strength ◽  
Aircraft Engine ◽  
Microstructural Stability ◽  
Directionally Solidified ◽  
In Situ Composites ◽  
Interface Reactions ◽  
Engine Components ◽  
Directionally Solidified Eutectics

New materials for high temperature aircraft engine components should have a good combination of low density and high strength at temperatures as high as 1300-1500°C. This will probably require the use of composite materials. In-situ composites, or directionally solidified eutectics, are good candidates for this demanding application and have major advantages over alternative synthetic composites, such as MoSi2-SiC or carbon-carbon composites. The fabrication of components from eutectic castings is simpler and eutectic alloys offer some intrinsic microstructural stability with no reinforcement-matrix interface reactions at high temperatures. We are investigating the Cr-Si, Nb-Si and V-Si eutectic systems as potential high temperature in-situ composites. In this paper, we present results on the microstructure and crystallography of the Cr-Cr3Si eutectic which has a eutectic composition of ∼15 at% Si and a melting temperature of ∼1705 °C.

Tensile Test of Heterogenic Welding Joint in Ambient Temperature or High Temperature

2011 ◽  
Vol 121-126 ◽  
pp. 3053-3057
Author(s):  
Shu Xu
Keyword(s):  
High Temperature ◽  
Tensile Test ◽  
Ambient Temperature ◽  
Room Temperature ◽  
High Strength ◽  
Tensile Tests ◽  
Welding Joint ◽  
Welding Joints ◽  
High Temperature Tensile ◽  
Strength And Ductility

In this paper, the high temperature tensile tests and ambient temperature tensile tests are performed. The high strength of the welding for 1Cr9Mo/45 and 0Cr18Ni9/45 is somewhat smaller than the ambient strength, but the elongation is improved. Both the high strength and ductility are decreased compared to the results of the room tests. The rupture is located in the side of 1Cr9Mo for the welding of 1Cr9Mo/0Cr18Ni9 at the room temperature, while the rupture is located in the side of 0Cr18Ni9 at high temperature. It is concluded that the strength in high temperature is decreased for 0Cr18Ni9. The rupture happens in the side of 45 for both heterogenic welding joints of 45/0Cr18Ni9 and 45/1Cr9Mo.

High-Temperature Instability of A Cr2Nb-Nb(Cr) Microlaminate Composite

1996 ◽  
Vol 54 ◽  
pp. 374-375
Author(s):  
M. Larsen ◽  
R.G. Rowe ◽  
D.W. Skelly
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
High Temperature ◽  
Elevated Temperatures ◽  
Aircraft Engine ◽  
Lattice Parameter ◽  
Microstructural Stability ◽  
Elevated Temperature Strength ◽  
Cross Sectional ◽  
Bcc Structure

Microlaminate composites consisting of alternating layers of a high temperature intermetallic compound for elevated temperature strength and a ductile refractory metal for toughening may have uses in aircraft engine turbines. Microstructural stability at elevated temperatures is a crucial requirement for these composites. A microlaminate composite consisting of alternating layers of Cr2Nb and Nb(Cr) was produced by vapor phase deposition. The stability of the layers at elevated temperatures was investigated by cross-sectional TEM.The as-deposited composite consists of layers of a Nb(Cr) solid solution with a composition in atomic percent of 91% Nb and 9% Cr. It has a bcc structure with highly elongated grains. Alternating with this Nb(Cr) layer is the Cr2Nb layer. However, this layer has deposited as a fine grain Cr(Nb) solid solution with a metastable bcc structure and a lattice parameter about half way between that of pure Nb and pure Cr. The atomic composition of this layer is 60% Cr and 40% Nb. The interface between the layers in the as-deposited condition appears very flat (figure 1). After a two hour, 1200 °C heat treatment, the metastable Cr(Nb) layer transforms to the Cr2Nb phase with the C15 cubic structure. Grain coarsening occurs in the Nb(Cr) layer and the interface between the layers roughen. The roughening of the interface is a prelude to an instability of the interface at higher heat treatment temperatures with perturbations of the Cr2Nb grains penetrating into the Nb(Cr) layer.

High temperature tensile behavior of Mg-2Al and Mg-6Al alloys

2018 ◽  
Vol 109 (1) ◽  
pp. 28-33 ◽  
Author(s):  
Jun Qiao ◽  
Long Zheng ◽  
Jiaxing Ji ◽  
Fubo Bian ◽  
Min He ◽  
...  
Keyword(s):  
High Temperature ◽  
Tensile Behavior ◽  
High Temperature Tensile

scholarly journals Europium monoxide as a basis for creating a high-temperature spin injector in the semiconductor spintronics

2020 ◽  
Vol 6 (3) ◽  
pp. 113-123
Author(s):  
Arnold S. Borukhovich
Keyword(s):  
Magnetic Field ◽  
Solid Solution ◽  
Composite Material ◽  
High Temperature ◽  
External Magnetic Field ◽  
Room Temperature ◽  
Spin Electronics ◽  
Wide Range ◽  
Semiconductor Spintronics ◽  
Europium Monoxide

The results of the creation of a high-temperature spin injector based on EuO: Fe composite material are discussed. Their magnetic, electrical, structural and resonance parameters are given in a wide range of temperatures and an external magnetic field. A model calculation of the electronic spectrum of the solid solution Eu–Fe–O, responsible for the manifestation of the outstanding properties of the composite, is performed. The possibility of creating semiconductor spin electronics devices capable of operating at room temperature is shown.

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