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Article
Creep in Polycrystalline Aluminum
This paper presents a study of creep in polycrystalline aluminum. The sample was deformed in a scanning electron microscope and local strain was measured by analyzing micrographs taken during the test. EBSP wa...
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Article
Fatigue Crack Initiation In WASPALOY at 20 °C
In two WASPALOY specimens, the orientations of grains that initiated fatigue cracks and adjacent ograins were measured using electron backscattered diffraction patterns (EBSP). Crystallographic relationships w...
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Article
Microstructural and fracture characterization of Nb-Cr-Ti mechanically alloyed materials
Three materials containing Nb, Cr, and Ti were fabricated by consolidating powders made by mechanical alloying. The Nb/Ti ratio was maintained at about 1.3 and Cr was increased to form the intermetallic Cr2Nb. X-...
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Article
Dislocation structures in a deformed Nb-Cr-Ti solid solution alloy
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Article
Fracture toughness of fabrics as composite reinforcements
An experimental technique is developed to measure the fracture toughness of fabrics using the variables normally associated with fracture mechanics: stress and crack length. The technique uses a fabric with a ...
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Article
Fatigue and fracture toughness of a Nb-Ti-Cr-Al-X single-phase alloy at ambient temperature
The fatigue and fracture resistance of a commercially made, single-phase Nb-base alloy with 35 at. pct Ti, 5 at. pct Cr, 6 at. pct Al, and several elements to increase solid solution strengthening have been in...
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Article
The fatigue and fracture resistance of a Nb-Cr-Ti-Al alloy
The microstructure, fatigue, and fracture behaviors of a cast and heat-treated Nb-Cr-Ti-Al alloy were investigated. The microstructure of the cast alloy was manipulated by annealing at a temperature ranging fr...
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Article
Optimizing the design of particulate composites for maximum fracture resistance through modeling
The failure modes of particulate reinforced metallic alloys are reviewed with special emphasis on in situ intermetallic particle reinforced niobium alloys, but information derived from ceramic reinforced alumi...
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Article
Fracture toughness and fatigue crack growth in rapidly quenched Nb-Cr-Ti In situ composites
In situ composites based on the Nb-Cr-Ti ternary system were processed by rapid solidification in order to reduce the size of the reinforcing intermetallic phase. Two-phase microstructures with s...
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Article
Local constraint near fatigue cracks in alloys and particulate composites
An experimental method with high spatial resolution has been developed for determining material constraint on the surface of specimens. The method uses strains computed from stereoimaging measurements of displ...
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Article
The effects on fracture toughness of ductile-phase composition and morphology in Nb-Cr-Ti and Nb-Siin situ composites
Niobium-chromium alloys, both single and two phase, were alloyed with titanium in order to enhance fracture toughness and fatigue crack growth resistance. The selection of titanium as an alloying element and t...
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Article
Cu-bearing high-strength low-alloy steels: The influence of microstructure on the initiation and growth of small fatigue cracks
The fatigue characteristics of a Cu-bearing high-strength low-alloy (HSLA) steel were investigated in air, relative humidity ≈50 pct, as a function of microstructure, which was altered by heat treatments and w...
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Article
The crack-tip mechanics and growth rates of small fatigue cracks in ASTROLOY
The micromechanics of naturally initiated small fatigue cracks in coarse- and fine-grained nickelbased ASTROLOY have been studied at ambient and elevated temperature using a cyclic loading stage for the scanni...
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Article
Molybdenum-Rhenium Disilicide Alloys
Rhenium was added to MoSi2 in two concentrations and billets were made by hot pressing powders. The microstructures obtained are reviewed. Fracture toughness was measured at 20 and 800°C, hardness was measured at...
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Article
Fatigue crack growth through the lamellar microstructure of an alloy based on TiAl at 25 °C and 800 °C
Fatigue cracks were grown at 25 °C and 800 °C in a titanium aluminide alloy heat-treated to give a γ+ α2 lamellar microstructure. These lamellae, having widths of =0.5 to 2 μm, were in colonies approximately 1.2 ...
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Article
Fatigue and Fracture of Nb3Al/Nb In Situ Composites Based on an Nb 18 at.% Al Alloy
Near Nb3Al alloys, having Nb3Al with the ordered A15 crystalographic structure within regions of Nb solid solution, can be considered as in-situ reinforced composites. Nb-18 at.%Al ingots were arc melted and heat...
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Article
The micromechanics of fatigue crack growth at 25 °C in Ti-6Al-4V reinforced with SCS-6 fibers
Micromechanics parameters for fatigue cracks growing perpendicular to fibers were measured for the center-notched specimen geometry. Fiber displacements, measured through small port holes in the matrix made by...
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Article
Near-tip behavior of deflected creep cracks
Near-tip displacement fields of a creep crack which exhibited moderate deflection from its initially mode I condition have been measured using the stereoimaging technique. From the measured displacement fields...
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Article
The initiation and growth of fatigue cracks in a titanium aluminide alloy
The micromechanics of small, naturally initiated fatigue cracks and large through-thickness fatigue cracks have been studied in the titanium aluminide alloy Super Alpha 2. The microstructure investigated had e...
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Article
Effects of interfacial strength on fatigue crack growth in a fiberreinforced Ti-alloy composite
The fatigue crack growth behavior of a Ti-6A1-4V composite with boron fibers was previously studied in the as-received and thermally exposed conditions. Fracture strengths of the composite, fiber, and interfac...
