Ductile-Phase Toughening in Niobium-Niobium Silicide Powder Processed Composites

1990 ◽  
Vol 194 ◽  
Author(s):  
Rama M. Nekkanti ◽  
Dennis M. Dimiduk
Keyword(s):  
Solid Solution ◽  
Volume Fraction ◽  
Plastic Behavior ◽  
Solid Solution Phase ◽  
Dramatic Improvement ◽  
Ductile Phase ◽  
Heat Treated ◽  
Powder Composites ◽  
Made In ◽  
Cleavage Failure

AbstractThe Nb-Si system offers a possibility of ductile-phase toughening of the brittle Nb5Si3 intermetallic with the terminal niobium-silicon solid solution. Powder composites have been made in which the volume fraction of the terminal Nb-Si phase is systematically varied in a matrix of Nb5Si3 in order to study the extent of toughening. The Nb-Si solid-solution phase was observed to exhibit cleavage failure under both as hot pressed and heat treated conditions, thereby limiting the toughening attained by the presence of this phase. Hot working of the composite results in a dramatic improvement in toughness because of a change in the plastic behavior and fracture mode of the terminal Nb-Si phase from brittle cleavage to a mixed mode of cleavage and ductile microvoid growth and coalescence (dimpled) fracture.

High Temperature Compression Properties of Ni3(Si,Ti) Based Intermetallic Compounds

2014 ◽  
Vol 783-786 ◽  
pp. 1129-1135
Author(s):  
Takehito Hagisawa ◽  
Hirokazu Madarame ◽  
Shinji Tanaka ◽  
Yasuyuki Kaneno ◽  
Takayuki Takasugi
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
High Temperature ◽  
Strain Rate ◽  
Volume Fraction ◽  
Solution Phase ◽  
Solid Solution Phase ◽  
Ti Alloy ◽  
Compression Properties ◽  
Ti Alloys

High temperature compression properties of Al-, Cr-or Nb-added Ni3(Si,Ti) based intermetallic compounds were investigated by uni-axial compression test and microstructural observation. The Al-or Cr-added Ni3(Si,Ti) alloys after homogenization heat treatment exhibited a two-phase microstructure consisting of L12and Ni-solid solution phases. The Nb-added Ni3(Si,Ti) alloy after homogenization heat treatment exhibited a triple-phase microstructure consisting of G-phase with D8a structure and Ni-solid solution phase in the L12matrix. The volume fraction of Ni-solid solution phase increased in order of Cr-, Nb-and Al-added Ni3(Si,Ti) alloys. The Cr-added Ni3(Si,Ti) alloy was deformable at high strain rate, while the Nb-added one was deformable at low strain rate. It can be considered that the deformability of Ni3(Si,Ti) at high temperature is closely correlated with volume fraction of Ni-solid solution phase and recrystallization behavior.

Formation of Alloy Phases at Fe-Al Interface by Ion Beam Mixing, asRevealed by Interface-Sensitive Conversion Electron Mössbauer Spectroscopic Measurements

1983 ◽  
Vol 25 ◽  
Author(s):  
V.P. Godbole ◽  
V.G. Bhide ◽  
S.V. Ghaisas ◽  
S.M. Kanetkar ◽  
S.M. Chaudhari ◽  
...  
Keyword(s):  
Solid Solution ◽  
Conversion Electron ◽  
Ion Beam ◽  
Least Square ◽  
Solid Solution Phase ◽  
Heat Treated ◽  
Natural Iron ◽  
Identical Manner ◽  
Different Temperatures ◽  
Argon Ion Bombardment

ABSTRACTThe physical processes associated with the formation of various normal as well as metastable phases at an ion beam mixed Fe-Al interface are studied by using a novel interfacesensitive Conversion Electron Mbssbauer Spectroscopic (CEMS) technique.This technique which has been introduced and used for the first time in these investigations, is based on the deposition of a thin (less than 50 A°) layer of enriched Fe 5 7 isotope (95.45% by composition) at the interface between the aluminium substrate and a post-deposited 250A° film of natural iron (only 2.2% of Fe 57), leading to a considerably enhanced spatial selectivity of the M~ssbauer information regarding the reactions occurring at the interface.A number of samples prepared in the manner mentioned above are subjected to an argon ion bombardment at an incident ion energy of 100 keV and a dose of ≃ 2 × 1016 ions/cm2 The ion beam mixed samples are annealed at different temperatures in the range between 300°C to 600°C for twenty minutes, to provide the thermal energy for the growth of different Fex Aly phases at the interface.Conversion Electron Mössbauer Spectroscopy is employed at each stage of the ion beam processing and annealing of the samples, to characterize the phases formed. All the Mbssbauer spectra are least square fitted using the MOSFIT programme to obtain the best-fit values of Mössbauer parameters. The results indicate a substantial broadening of the Mössbauer lines for the as-implanted samples, a fact which can be attributed to the beam induced radiation damage. Subsequent annealing of the samples at different temperatures leads to annealing of damage and further to the formation of Fe3 Al and FeAl solid solution. Mössbauer spectra of the samples annealed at 500°C indicate segregation of Fe at the interface along with the formation of Fe3Al phase, while annealing at 600°C results in the formation of Fe-Al solid solution phase with traces of effectively unreacted metallic Fe. The unimplanted composites heat-treated in an identical manner do not show these features. These results which are supported by RBS measurements, are interpreted and discussed in terms of the non-equilibrium nature of the ion beam processing of the interface.

Solidification Processing and Fracture Behavior of RuAl-Based Alloys

2004 ◽  
Vol 842 ◽  
Author(s):  
Todd Reynolds ◽  
David Johnson
Keyword(s):  
Solid Solution ◽  
Fracture Toughness ◽  
Fracture Behavior ◽  
Room Temperature ◽  
Volume Fraction ◽  
Solidification Processing ◽  
Ductile Phase

ABSTRACTAlloys of RuAl-Ru were processed using various solidification methods, and the fracture behavior was examined. The fracture toughness values for RuAl-hcp(Ru, Mo) and RuAl-hcp(Ru, Cr) alloys ranged from 23 to 38 MPa√m, while the volume fraction of RuAl ranged from 22 to 56 percent. Increasing the volume fraction of RuAl resulted in a decrease in fracture toughness. The hcp solid solution was shown to be the more ductile phase with a fracture toughness approaching 68 MPa?m, while the B2 solid solution (RuAl) was found to have a fracture toughness less than 13 MPa√m. An alloy of Ru-7Al-38Cr (at.%) that consisted of a hcp matrix with RuAl precipitates had the highest room temperature toughness and the greatest hardness.

Facet crystallography of fractured V(2.7 wt% Si) solid solution

1994 ◽  
Vol 52 ◽  
pp. 622-623
Author(s):  
J. A. Sutliff ◽  
B. P. Bewlay ◽  
G. A. Henshall ◽  
M. J. Strum
Keyword(s):  
Solid Solution ◽  
Morphological Structure ◽  
Crystallographic Analysis ◽  
Solid Solution Alloy ◽  
Solid Solution Phase ◽  
Ductile Phase ◽  
High Temperature Alloys ◽  
Sem Micrograph ◽  
Facet Surface

V-Si binary alloys have been investigated as model high temperature alloys. Alloys with compositions between ~4 and 11 wt% Si can be fabricated as in-situ composites composed of the intermetallic V3Si phase and the V(Si) solid solution phase with a eutectic temperature of ~1870°C. The V(Si) phase is thought to be a ductile phase which provides toughness to the composite. We have previously reported on the fracture toughness of V-Si alloys.In this paper we present results on the fracture surface fractography and fracture facet crystallography of an arc-melted V(2.7 wt% Si) solid solution alloy fractured in bending. Figure 1 is a low magnification SEM micrograph of the surface of one half of a fractured bend bar. Many macroscopically flat facets can be seen and those for which crystallographic analysis was done have been labeled. Actually, the macro-facet surface as seen at higher magnification exhibits significant morphological structure, as can be observed in Figure 2 which shows detail of the facet labeled k.

scholarly journals Welding of Copper to Aluminium With Laser Beam Wavelength of 515 nm

2021 ◽  
Author(s):  
Karthik Mathivanan ◽  
Peter Plapper
Keyword(s):  
Solid Solution ◽  
Laser Beam ◽  
Laser Power ◽  
Solid Solution Phase ◽  
Research Focus ◽  
Mixed Composition ◽  
Ductile Phase ◽  
Laser Joining ◽  
Joint Fracture ◽  
Strong Joint

In laser joining of copper (Cu) and aluminum (Al) sheets, the Al sheet is widely chosen as the top surface for laser irradiation because of increased absorption of laser beam and lower melting temperature of Al in contrast to Cu. This research focus on welding from Cu side to Al sheet. The main objective of irradiating the laser beam from the copper side (Cu on top) is to exploit higher solubility of Al in Cu. A significantly lower laser power can be used with 515 nm laser in comparison to 1030 nm. In addition to low laser power, a stable welding is obtained with 515 nm. Because of this advantage, 515 nm is selected for the current research. By fusion of Cu and Al the two sheet metals are welded, with presence of beneficial Cu solid solution phase and Al+Al2Cu in the joint with the brittle phases intermixed between the ductile phase. Therefore the mixed composition strengthens the joint. However excessive mixing leads to formation of more detrimental phases and less ductile phases. Therefore optimum mixing must be maintained. Energy dispersive X-ray spectroscopy (EDS) analysis indicate that large amount of beneficial Cu solid solution and Al rich phases is formed in the strong joint. From the tensile shear test for a strong joint, fracture is obtained on the heat-affected zone (HAZ) of Al. Therefore the key for welding from copper side is to have optimum melt with beneficial phases like Cu and Al+ Al2Cu and the detrimental phases intermixed between the ductile phases

Effect of Particle Size of Mo Solid Solution on Hardness of Mo5SiB2/Mo-Based Alloys

2008 ◽  
Vol 1128 ◽  
Author(s):  
Kyosuke Yoshimi ◽  
Yusuke Kondo ◽  
Kouichi Maruyama
Keyword(s):  
Solid Solution ◽  
Particle Size ◽  
Vickers Hardness ◽  
Volume Fraction ◽  
Average Particle Size ◽  
Ternary Alloys ◽  
Average Particle ◽  
Ductile Phase ◽  
Cracking Behavior ◽  
Fine Microstructure

AbstractThree kinds of Mo-Si-B ternary alloys and a 1 at.% Al added Mo-Si-B alloy with the compositions near Mo-8.7 at.% Si-17.4 at.% B that is in the Mo5SiB2 and Mo two-phase compositional region were produced by Ar arc-melting followed by the heat treatment at 1800 °C for 24 h. These alloys have the characteristic fine microstructure composed of small Mo solid solution (Moss) particles in the Mo5SiB2 (T2) matrix with the primary phase (Moss or T2 depending on composition). The volume fraction of the Moss particles ranges from 25.5 to 30.5 % and its average size from 3.0 to 6.4 μm in the fine microstructure of the alloys. Micro cracks were introduced by Vickers hardness tests into the microstructures, and their propagation is disturbed by the small Moss particles. Thus, each hardness value seems to relate to the cracking behavior around each indent. On the other hand, Vickers hardness values do not show correlation with the volume fraction of the Moss particles, but clearly decrease with increasing the average particle size of Moss. Therefore, it should be concluded that the increase in the particle size of Moss could enhance the toughness of the Mo5SiB2/Mo-based alloys effectively by ductile phase toughening.

Multiphase Mo-Si-B alloys processed by directional solidification

2012 ◽  
Vol 1516 ◽  
pp. 303-308 ◽  
Author(s):  
Manja Krüger ◽  
Georg Hasemann ◽  
Iurii Bogomol ◽  
Petr I. Loboda
Keyword(s):  
Solid Solution ◽  
Volume Fraction ◽  
Microstructural Characterization ◽  
Zone Melting ◽  
Solution Phase ◽  
Solid Solution Phase ◽  
Creep Tests ◽  
Compression Creep ◽  
Fabrication Procedure ◽  
Cold Pressed

ABSTRACTMultiphase Mo-Si-B alloys are potential candidates for applications in the aerospace and power generation industry due to their enhanced creep and oxidation resistance at ultra-high temperatures. It is documented that the microstructure and the resulting properties of Mo-based alloys are heavily influenced by their fabrication procedure. In this study we investigate different multiphase Mo-Si-B alloys processed by zone melting (ZM) starting from cold pressed elemental powders. Microstructural characterization of zone melted alloys based on SEM investigations shows elongated arrangements of phases parallel to the growing direction as well as homogeneously distributed phases in the cross-section for some of the alloys investigated. First compression creep tests were performed at about 1100°C. In comparison to the creep resistance of powder metallurgically (PM) processed alloys the behaviour of ZM materials was found to be substantially improved. Hence, targeted application temperatures of around 1200°C to 1300°C may become feasible. Furthermore, the oxidation behaviour was found to be influenced by the volume fraction of the Mo solid solution phase since the volatilization of the Mo solid solution phase leads to a mass loss of the compound.

Fine Microstructure of a Mechanically Alloyed Oxide Dispersion Strengthened Nickel-Base Superalloy

1977 ◽  
Vol 35 ◽  
pp. 298-299
Author(s):  
Jordi Marti ◽  
Timothy E. Howson ◽  
David Kratz ◽  
John K. Tien
Keyword(s):  
Solid Solution ◽  
Volume Fraction ◽  
Stress Rupture ◽  
Oxide Dispersion Strengthened ◽  
Solid Solution Alloy ◽  
Oxide Dispersion ◽  
Creep And Stress Rupture ◽  
Mechanically Alloyed ◽  
Fine Microstructure ◽  
Nickel Base

The previous paper briefly described the fine microstructure of a mechanically alloyed oxide dispersion strengthened nickel-base solid solution. This note examines the fine microstructure of another mechanically alloyed system. This alloy differs from the one described previously in that it is more generously endowed with coherent precipitate γ forming elements A1 and Ti and it contains a higher volume fraction of the finely dispersed Y2O3 oxide. An interesting question to answer in the comparative study of the creep and stress rupture of these two ODS systems is the role of the precipitate γ' in the mechanisms of creep and stress rupture in alloys already containing oxide dispersoids.The nominal chemical composition of this alloy is Ni - 20%Cr - 2.5%Ti - 1.5% A1 - 1.3%Y203 by weight. The system receives a three stage heat treatment-- the first designed to produce a coarse grain structure similar to the solid solution alloy but with a smaller grain aspect ratio of about ten.

AEM investigation of ZrO2 solid solution formation in ZrO2/mullite composites

1984 ◽  
Vol 42 ◽  
pp. 408-409
Author(s):  
T. R. Dinger
Keyword(s):  
Solid Solution ◽  
Ion Beam ◽  
Analytical Electron Microscopy ◽  
Transformation Toughening ◽  
Solid Solution Formation ◽  
Solution Formation ◽  
Propagating Crack ◽  
Analytical Electron ◽  
Microcrack Toughening ◽  
Made In

Zirconia (ZrO2) is often added to ceramic compacts to increase their toughness. The mechanisms by which this toughness increase occurs are generally accepted to be those of transformation toughening and microcracking. The mechanism of transformation toughening is based on the presence of metastable tetragonal ZrO2 which transforms to the monoclinic allotrope when stressed by a propagating crack. The decrease in volume which accompanies this transformation effectively relieves the applied stress at the crack tip and toughens the material; microcrack toughening arises from the deflection of a propagating crack around sharply angular inclusions.These mechanisms, however, do not explain the toughness increases associated with the class of composites investigated here. Analytical electron microscopy (AEM) has been used to determine whether solid solution effects could be the cause of this increased toughness. Specimens of a mullite (3Al2O3·2SiO2) + 15 vol. % ZrO2 were prepared by the usual technique of mechanical thinning followed by ion beam milling. All observations were made in a Philips EM400 TEM/STEM microscope fitted with EDXS and EELS spectrometers.

Transition alpha structure in beta-isomorphous Nb-Hf alloys

1987 ◽  
Vol 45 ◽  
pp. 232-233
Author(s):  
R.W. Carpenter ◽  
Changhai Li ◽  
David J. Smith
Keyword(s):  
Solid Solution ◽  
Solution Phase ◽  
Miscibility Gap ◽  
Large Strains ◽  
Solid Solution Phase ◽  
Two Phase ◽  
Diffuse Intensity ◽  
Metastable Form ◽  
The Matrix ◽  
Equilibrium Morphology

Binary Nb-Hf alloys exhibit a wide bcc solid solution phase field at temperatures above the Hfα→ß transition (2023K) and a two phase bcc+hcp field at lower temperatures. The β solvus exhibits a small slope above about 1500K, suggesting the possible existence of a miscibility gap. An earlier investigation showed that two morphological forms of precipitate occur during the bcc→hcp transformation. The equilibrium morphology is rod-type with axes along <113> bcc. The crystallographic habit of the rod precipitate follows the Burgers relations: {110}||{0001}, <112> || <1010>. The earlier metastable form, transition α, occurs as thin discs with {100} habit. The {100} discs induce large strains in the matrix. Selected area diffraction examination of regions ∼2 microns in diameter containing many disc precipitates showed that, a diffuse intensity distribution whose symmetry resembled the distribution of equilibrium α Bragg spots was associated with the disc precipitate.

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