54 Result(s)
within
K.S. Chan
Materials Science
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Article
MicroROM: A Physics-Based Constitutive Model for Ni-Based Superalloys
In this article, a physics-based constitutive model is developed for representing the stress–plastic strain response of Ni-based superalloys by considering the hardening mechanisms that contribute to the macro...
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Article
Fatigue Crack Prognostics by Optical Quantification of Defect Frequency
Defect frequency, a fatigue crack prognostics indicator, is defined as the number of microcracks per second detected using a laser beam that is scanned across a surface at a constant predetermined frequency. I...
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Article
Fracture toughness of zirconia nanoparticle-filled dental composites
The fracture toughness of dental composites containing zirconia nanoparticles dispersed in a bisphenol A glycol dimethacrylate-based monomer blend (GTE) was studied for several yttria contents. Three-point ben...
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Article
Evolution of Slip Morphology and Fatigue Crack Initiation in Surface Grains of Ni200
The evolution of slipbands into fatigue cracks in surface grains of commercially pure Ni, Ni200 (99.35Ni-0.4Fe-0.25Cu, in wt pct), was studied at ambient temperature. Round-bar specimens with electropolished s...
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Article
In-Situ Fracture Studies and Modeling of the Toughening Mechanism Present in Wrought Low-Carbon Arc-Cast Molybdenum, Titanium-Zirconium-Molybdenum, and Oxide-Dispersion-Strengthened Molybdenum Flat Products
In-situ testing, ultrasonic C-scans, and metallography were used to show that a crack-divider delamination form of thin-sheet toughening occurs in wrought low-carbon arc-cast (LCAC) unall...
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Article
Effects of Deformation-Induced Constraint on High-Cycle Fatigue in Ti Alloys with a Duplex Microstructure
The effects of the deformation behaviors of individual phases in Ti alloys with a duplex microstructure containing a mixture of primary α grains and lamellar α + β colonies have been analyzed by applying the fini...
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Article
An Experimental Study of Fracture of LIGA Ni Micro-Electro-Mechanical Systems Thin Films
This article presents the results of an experimental study of fracture in LIGA Ni micro-electro-mechanical systems (MEMS) thin films. Microtesting techniques are developed for the study of the J-resistance curve ...
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Article
A Probabilistic-Micromechanical Methodology for Assessing Zirconium Alloy Cladding Failure
Cladding failure of fuel rods caused by hydride-induced embrittlement is a reliability concern for spent nuclear fuel after extended burnup. Uncertainties in the cladding temperature, cladding stress, oxide la...
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Article
Durability of Fe-Co thin films on Ti-6Al-4V
The durability of Fe-Co thin films bonded on Ti-6Al-4V was studied as a function of layer thickness at ambient temperature. Interface toughness of the thin films was characterized by indentation and analyzed u...
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Article
First-principles computations of mechanical properties of Ni2Cr and Ni2Mo
Nickel-based alloys are being considered for use as the outer container of the waste package for the disposal of high-level nuclear waste. During fabrication processes and long-term storage, Ni-based alloy out...
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Article
Cyclic-Oxidation Resistance of Niobium-Base in situ Composites: Modeling and Experimentation
Despite significant improvements in recent years, the oxidation resistance of niobium-base in situ composites is still inadequate for high-temperature applications because of their fast oxidation and the diffi...
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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
An In-Situ Study of Crack Propagation in Binary Lamellar TiAl
Single-colony thick compact tension specimens of binary lamellar Ti-46.5%Al were tested within a scanning electron microscope to examine the contribution of colony boundaries to crack growth resistance under m...
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Article
Constitutive properties of hard-alpha titanium
The flow and fracture behavior of hard-alpha Ti was studied as a function of nitrogen content, stress state, strain rate, and temperature. Hard-alpha Ti specimens with nitrogen contents ranging from 2 to 11.6 ...
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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
Scientific Bases for Cladding Credit as a Barrier to Radionuclide Release at the Proposed Yucca Mountain Repository
The performance of Zircaloy nuclear fuel cladding in the environment of the proposed Yucca Mountain (YM) high-level waste (HLW) repository is evaluated. Because the uniform aqueous corrosion/oxidation rate is ...
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Article
Fundamental aspects of fatigue and fracture in a TiAl sheet alloy
The fatigue mechanisms in a TiAl sheet alloy, heat treated to the lamellar and equiaxed microstructures, were studied to determine the effects of microstructure on the initiation of microcracks and their subse...
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Article
The Effect of Tensile Strain on AlGaAs/GaAsP Interdiffused Quantum Well Laser
In this paper, we study the interdiffusion of tensile strained GaAsyPi.y /A10 33Ga0 67As single QW structures with a well width of 60 Å. Different P concentrations in the as-grown well are chosen to obtain dif...
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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...
