scholarly journals 1300 K Compressive Properties of a Reaction Milled NiAl-AlN Composite

1990 ◽  
Vol 194 ◽  
Author(s):  
J. Daniel Whittenberger ◽  
Eduard Arzt ◽  
Michael J. Luton
Keyword(s):  
Stress Exponent ◽  
Nickel Aluminide ◽  
Thermomechanical Processing ◽  
Hot Isostatic Pressing ◽  
Small Diameter ◽  
Hot Extrusion ◽  
Second Phase ◽  
Strain Rates ◽  
Reaction Milling ◽  
The Matrix

AbstractCryomilling (high intensity mechanical ball milling in a liquid nitrogen bath) of the B2 crystal structure nickel aluminide leads to a NiAl-AlN composite containing about 10 vol pct second phase which is dispersed as very small diameter (< 50 nm) AlN particles in a mantle surrounding particle-free NiAl grains. The AlN particles are the result of reaction milling, where nitrogen incorporated into the matrix during cryomilling reacts with Al during subsequent thermomechanical processing to form a composite. Compressive testing at 1300 K of such materials densified by either hot extrusion or hot isostatic pressing have indicated that strength at relatively fast strain rates (>10−7 s−1 ) is dependent on the method of consolidation; however no clear dependency on densification technique appears to exist at slower rates. In addition deformation at 1300 K occurs by two distinct mechanisms, where at high strain rates the stress exponent is greater than 13 while at slower rates (< 10−7 s−1) a much lower stress exponent (∼6) was found.

scholarly journals 1300 K compressive properties of a reaction milled NiAl–AlN composite

1990 ◽  
Vol 5 (12) ◽  
pp. 2819-2827 ◽  
Author(s):  
J. Daniel Whittenberger ◽  
Eduard Arzt ◽  
Michael J. Luton
Keyword(s):  
Stress Exponent ◽  
Nickel Aluminide ◽  
Thermomechanical Processing ◽  
Milling Process ◽  
Strain Rates ◽  
Reaction Milling ◽  
The Matrix ◽  
Compressive Testing ◽  
Liquid Nitrogen Bath ◽  
Base Superalloy

Cryomilling (high intensity mechanical ball milling in a liquid nitrogen bath) of the B2 crystal structure nickel aluminide leads to a NiAl composite containing about 10 vol.% of AlN particles. This is the result of a reaction milling process, where nitrogen incorporated into the matrix during cryomilling reacts with Al during subsequent thermomechanical processing to form the composite. Compressive testing at 1300 K of such materials densified by 1505 K extrusion or isostatic pressing at 1323 K or 1623 K indicated that strength at relatively fast strain rates (>10−7 s−1) is slightly dependent on the method of consolidation. At slower rates, however, no clear dependency on densification technique appears to exist, and four different consolidation methods possessed similar creep strengths. In all cases deformation at 1300 K occurred by two distinct mechanisms: at high strain rates the stress exponent is greater than 11 while at slower rates (<10−7 s−1) a much lower stress exponent (∼6) was found. Comparison of density compensated creep strengths reveals that the properties of NiAl–AlN are similar to those of the single crystal Ni-base superalloy NASAIR 100.

Microstructure and Mechanical Bevavior of Ni3Al-Matrix Composites

1990 ◽  
Vol 194 ◽  
Author(s):  
P. C. Brennan ◽  
W. H. Kao ◽  
S. M. Jeng ◽  
J.-M. Yang
Keyword(s):  
Yield Strength ◽  
Nickel Aluminide ◽  
Fracture Stress ◽  
Room Temperature ◽  
Hot Extrusion ◽  
Matrix Composites ◽  
The Matrix ◽  
Bend Tests ◽  
Point Bend ◽  
Particulate Reinforced

AbstractAn aluminum oxide particulate-reinforced nickel-aluminide composite was fabricated by vacuum hot pressing and hot extrusion. Room temperature three point bend tests were conducted after 1 and 100 h at 1000 °C. The composite exhibited a decrease in yield strength from 772 to 517 MPa after 100 h while the ultimate fracture stress decreased from 1174 to 998 MPa. The strain to failure increased from 4.6% to 6.0% after the same exposure. Saphikon single crystal Al2O3 fibers were used to demonstrate the materials' compatibility. The fracture surfaces of the failed composites indicated ductile failures in the matrix and decohesion between the particles and matrix.

scholarly journals Hot-Extruded and Cold-Rolled Textures of the Matrix Aluminum in Deformation Processed Two-Phase Nb/Al Metal-Metal Composites

2003 ◽  
Vol 35 (3-4) ◽  
pp. 273-282 ◽  
Author(s):  
L. Q. Chen ◽  
N. Kanetake
Keyword(s):  
Cold Rolling ◽  
Hot Extrusion ◽  
Orientation Distribution ◽  
Rolling Process ◽  
Distribution Functions ◽  
Second Phase ◽  
Metal Composite ◽  
Two Phase ◽  
Metal Metal ◽  
The Matrix

In this article, the powder metallurgy technique combined with flat hot-extrusion and cold rolling processes was employed to fabricate 10 and 20vol.%Nb/Al metal–metal composite sheets. The hot-extruded and coldrolled textures of the matrix aluminum in these metal–metal composite sheets were investigated by three dimensional orientation distribution functions (ODFs) analysis. The results show that the extrusion mode and large second phase particulate metal, Nb, have strong influence on the development of the extrusion and cold rolling textures in composites’ matrix. The matrix Al forms β-fiber textures after flat hot extrusion, where the components consist of B′-{011} ‹322›, S′-{124} ‹654› and C′-{113}h332i. After cold rolling process, only B′-{011} ‹322› changed to B-{011} ‹211› while the other components remained the same. The large particles in composites affect the matrix deformation in such a way that separates the distorted or bound zones from the deformation zones, which resulted in the final cold rolling deformation textures.

TEM Studies of Grain Boundary Films in Si3N4 Ceramics

1991 ◽  
Vol 49 ◽  
pp. 930-931
Author(s):  
H.-J. Kleebe ◽  
J.S. Vetrano ◽  
J. Bruley ◽  
M. Rühle
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Hot Isostatic Pressing ◽  
Amorphous Film ◽  
Liquid Phase Sintering ◽  
Second Phase ◽  
High Temperature Mechanical Properties ◽  
Triple Points ◽  
Boundary Films

It is expected that silicon nitride based ceramics will be used as high-temperature structural components. Though much progress has been made in both processing techniques and microstructural control, the mechanical properties required have not yet been achieved. It is thought that the high-temperature mechanical properties of Si3N4 are limited largely by the secondary glassy phases present at triple points. These are due to various oxide additives used to promote liquid-phase sintering. Therefore, many attempts have been performed to crystallize these second phase glassy pockets in order to improve high temperature properties. In addition to the glassy or crystallized second phases at triple points a thin amorphous film exists at two-grain junctions. This thin film is found even in silicon nitride formed by hot isostatic pressing (HIPing) without additives. It has been proposed by Clarke that an amorphous film can exist at two-grain junctions with an equilibrium thickness.

Polishing process effect on the image of dispersed precipitates

1984 ◽  
Vol 42 ◽  
pp. 534-535
Author(s):  
C.T. Hu ◽  
C.W. Allen
Keyword(s):  
Matrix Material ◽  
Specimen Preparation ◽  
Second Phase ◽  
Precipitate Particle ◽  
Polishing Process ◽  
Second Phase Particles ◽  
The Matrix ◽  
Surface Profiles ◽  
Thinning Process

One important problem in determination of precipitate particle size is the effect of preferential thinning during TEM specimen preparation. Figure 1a schematically represents the original polydispersed Ni3Al precipitates in the Ni rich matrix. The three possible type surface profiles of TEM specimens, which result after electrolytic thinning process are illustrated in Figure 1b. c. & d. These various surface profiles could be produced by using different polishing electrolytes and conditions (i.e. temperature and electric current). The matrix-preferential-etching process causes the matrix material to be attacked much more rapidly than the second phase particles. Figure 1b indicated the result. The nonpreferential and precipitate-preferential-etching results are shown in Figures 1c and 1d respectively.

Deformation at interfaces of Ti-6Al-4V/SiC fiber composites

1992 ◽  
Vol 50 (1) ◽  
pp. 158-159
Author(s):  
Warren J. Moberly ◽  
Daniel B. Miracle ◽  
S. Krishnamurthy
Keyword(s):  
Thermal Stresses ◽  
Load Transfer ◽  
Coefficient Of Thermal Expansion ◽  
Hot Isostatic Pressing ◽  
Matrix Composites ◽  
Ongoing Research ◽  
Aerospace Applications ◽  
Sic Fiber ◽  
The Matrix ◽  
Intermetallic Matrix Composites

Titanium-aluminum alloy metal matrix composites (MMC) and Ti-Al intermetallic matrix composites (IMC), reinforced with continuous SCS6 SiC fibers are leading candidates for high temperature aerospace applications such as the National Aerospace Plane (NASP). The nature of deformation at fiber / matrix interfaces is characterized in this ongoing research. One major concern is the mismatch in coefficient of thermal expansion (CTE) between the Ti-based matrix and the SiC fiber. This can lead to thermal stresses upon cooling down from the temperature incurred during hot isostatic pressing (HIP), which are sufficient to cause yielding in the matrix, and/or lead to fatigue from the thermal cycling that will be incurred during application, A second concern is the load transfer, from fiber to matrix, that is required if/when fiber fracture occurs. In both cases the stresses in the matrix are most severe at the interlace.

The hot extrusion reaction synthesis of nickel aluminide alloys

2004 ◽  
Vol 12 (1) ◽  
pp. 75-84 ◽  
Author(s):  
E.J. Minay ◽  
H.B. McShane ◽  
R.D. Rawlings
Keyword(s):  
Nickel Aluminide ◽  
Hot Extrusion ◽  
Reaction Synthesis ◽  
Extrusion Reaction

scholarly journals Welding thermal cycle-triggered precipitation processes in steel S700MC subjected to the thermo-mechanical control processing

2017 ◽  
Vol 62 (1) ◽  
pp. 321-326 ◽  
Author(s):  
J. Górka
Keyword(s):  
Thermomechanical Processing ◽  
Control Process ◽  
Base Material ◽  
Structural Defects ◽  
Accelerated Cooling ◽  
Internal Stresses ◽  
Mechanical Control ◽  
Thin Foils ◽  
Precipitation Processes ◽  
The Matrix

Abstract This study presents tests concerned with welding thermal process-induced precipitation processes taking place in 10 mm thick steel S700MC subjected to the Thermo-Mechanical Control Process (TMCP) with accelerated cooling. The thermomechanical processing of steel S700MC leads to its refinement, structural defects and solutioning with hardening constituents. Tests of thin foils performed using a transmission electron microscope revealed that the hardening of steel S700MC was primarily caused by dispersive (Ti,Nb)(C,N) precipitates (being between several and less than twenty nanometers in size). In arc welding, depending on a welding method and linear energy, an increase in the base material in the weld is accompanied by the increased concentration of hardening microagents in the weld. The longer the time when the base material remains in the liquid state, the greater the amount of microagents dissolved in the matrix. During cooling, such microagents can precipitate again or remain in the solution. An increase in welding linear energy is accompanied by an increase in the content of hardening phases dissolved in the matrix and, during cooling, by their another uncontrolled precipitation in the form of numerous fine-dispersive (Ti,Nb)(C,N) precipitates of several nm in size, leading to a dislocation density increase triggered by type 2 internal stresses.

Recrystallization in Ultra-Fine Grain Structures of AA3104 Alloy Processed by ECAP and HPT

2012 ◽  
Vol 715-716 ◽  
pp. 346-353
Author(s):  
H. Paul ◽  
T. Baudin ◽  
K. Kudłacz ◽  
A. Morawiec
Keyword(s):  
High Pressure Torsion ◽  
Deformation Mode ◽  
Second Phase ◽  
Orientation Measurement ◽  
Angular Pressing ◽  
Second Phase Particles ◽  
Average Grain Size ◽  
The Matrix ◽  
Electron Microscopes ◽  
Different Strains

The objective of this study was to determine the effect of deformation mode on recrystallization behavior of severely deformed material. Commercial purity AA3104 aluminum alloy was deformed via high pressure torsion and equal channel angular pressing to different strains and then annealed to obtain the state of partial recrystallization. The microstructure and the crystallographic texture were analysed using scanning and transmission electron microscopes equipped with orientation measurement facilities. The nucleation of new grains was observed in bulk recrystallized samples and during in-situ recrystallization in the transmission microscope. Irrespective of the applied deformation mode, a large non-deformable second phase particles strongly influenced strengthening of the matrix through deformation zones around them. It is known that relatively high stored energy stimulates the nucleation of new grains during the recrystalization. In most of the observed cases, the growth of recrystallized grains occurred by the coalescence of neighboring subcells. This process usually led to nearly homogeneous equiaxed grains of similar size. The diameter of grains in the vicinity of large second phase particles was only occasionally significantly larger than the average grain size. Large grains were most often observed in places far from the particles. TEM orientation mapping from highly deformed zones around particles showed that orientations of new grains were not random and only strictly defined groups of orientations were observed.

Development of Ni/h-BN Self-Lubricating Composite Powder by High-Energy Ball Milling

2016 ◽  
Vol 869 ◽  
pp. 277-282
Author(s):  
Moisés Luiz Parucker ◽  
César Edil da Costa ◽  
Viviane Lilian Soethe
Keyword(s):  
Ball Milling ◽  
Milling Time ◽  
Solid Lubricants ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Second Phase ◽  
Average Particle ◽  
Composite Powders ◽  
The Matrix ◽  
Energy Ball

Solid lubricants have had good acceptance when used in problem areas where the conventional lubricants cannot be applied: under extreme temperatures, high charges and in chemically reactive environments. In case of materials manufactured by powder metallurgy, particles of solid lubricants powders can be easily incorporated to the matrix volume at the mixing stage. In operation, this kind of material provides a thin layer of lubricant that prevents direct contact between the surfaces. The present study aimed at incorporating particles of second phase lubricant (h-BN) into a matrix of nickel by high-energy ball milling in order to obtain a self-lubricating composite with homogeneous phase distribution of lubricant in the matrix. Mixtures with 10 vol.% of h-BN varying the milling time of 5, 10, 15 and 20 hours and their relationship ball/powder of 20:1 were performed. The effect of milling time on the morphology and microstructure of the powders was studied by X-ray diffraction, SEM and EDS. The composite powders showed reduction in average particle size with increasing milling time and the milling higher than 5 hours resulted in equiaxial particles and the formation of nickel boride.

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