Fracture toughness and crack-resistance curve behavior in metallic glass-matrix composites (2009)
Launey, M. E., Hofmann, D. C., Kozachkov, H., Johnson, W. L., Ritchie, R. O.
Nonlinear-elastic fracture mechanics methods are used to assess the fracture toughness of bulk metallic glass (BMG) composites; results are compared with similar measurements for other monolithic and...
W. L. Johnson, S. Marsella, H. Vilhjálmsson
The DARWARS Tactical Language Training System (TLTS) helps learners acquire basic communicative skills in foreign languages and cultures. Learners practice their communication skills in a simulated...
Oxidation behaviour of metallic glass foams (2008)
Barnard, B. R., Liaw, P. K., Demetriou, M. D., Johnson, W. L.
In this study, the effects of porosity on the oxidation behaviour of bulk-metallic glasses were investigated. Porous Pd- and Fe-based bulk-metallic glass (BMG) foams and Metglas ribbons were studied....
Heterogeneous nucleation in a glass-forming alloy (2008)
Wall, J. J., Liu, C. T., Li, J. J. Z., Liaw, P. K., Choo, H., ...
Nucleation in the undercooled liquid state in the bulk metallic glass-forming composition Zr52.5Cu17.9Ni14.6Al10Ti5 (VIT-105), produced using high purity (PA) and commercial purity (CA) raw materials...
K. Ohsaka, S. K. Chung, W. K. Rhim, A. Peker, D. Scruggs, W. L. Johnson
The specific volumes of the Zr4 1.~Ti l~.gCu 12.5Ni
Calculation of Mechanical, Thermodynamic and Transport Properties of Metalic Glass formers (2007)
T. Cagin, Y. Qi, H. Li, Y. Kimura, H. Ikeda, W. L. Johnson, ...
Recently, wehave parametrized Sutton-Chen type empirical many body force elds for FCC transition metals to study the thermodynamic, mechanical, transport and phase behavior of metals and their...
Pseudo-binary phase diagram for Zr-based in situ ß phase composites (2007)
Lee, S. Y., Kim, C. P., Almer, J. D., Lienert, U., Ustundag, E., Johnson, W. L.
The pseudo-binary (quasi-equilibrium) phase diagram for Zr-based bulk metallic glasses with crystalline in situ precipitates (ß phase) has been constructed from high-temperature phase information...
Toward the Holodeck: Integrating Graphics, Sound, Character and Story (2007)
Swartout, W., Hill, R., Gratch, J., Johnson, W. L., Kyriakakis, C., LaBore, C., ...
We describe an initial prototype of a holodeck-like environment that we have created for the Mission Rehearsal Exercise Project. The goal of the project is to create an experience learning system...
Limited Domain Synthesis of Expressive Military Speech for Animated Characters (2007)
Johnson, W. L., Narayanan, Shrikanth, Whitney, Richard, Das, Rajat, LaBore, Catherine
Text-to-speech synthesis can play an important role in interactive education and training applications, as voices for animated agents. Such agents need high-quality voices capable of expressing...
Limited Domain Synthesis of Expressive Military Speech for Animated Characters (2007)
Johnson, W. L., Narayanan, S., Whitney, R., Das, R., Bulut, M., LaBore, C.
Text-to-speech synthesis can play an important role in interactive education and training applications, as voices for animated agents. Such agents need high-quality voices capable of expressing...
Fan, G. J., Freels, M., Choo, H., Liaw, P. K., Li, J. J. Z., Rhim, Won-Kyu, ...
By employing a containerless high-temperature high-vacuum electrostatic levitation technique, the thermophysical properties, including the ratio between the specific heat capacity and the...
On the existence of Einstein oscillators and thermal conductivity in bulk metallic glass (2006)
Zhou, Zhenhua, Uher, Ctirad, Xu, Donghua, Johnson, W. L., Gannon, W., Aronson, M. C.
Low-temperature specific heat and thermal conductivity of bulk metallic glasses are measured to identify the primary vibrational modes associated with their unique structures. An Einstein-type...
Validity of temperature and time equivalence in metallic glasses during shear deformation (2006)
Zink, Mareike, Samwer, K., Johnson, W. L., Mayr, S. G.
Competing internal and external time scales, which are determined by temperature and experimental sampling time—viz., reciprocal frequency—respectively, are essentials for understanding the...
Thermophysical properties of a Cu46Zr42Al7Y5 bulk metallic glass-forming liquid (2006)
Fan, G. J., Li, J. J. Z., Rhim, Won-Kyu, Qiao, D. C., Choo, H., Liaw, P. K., ...
The thermophysical properties, including the specific volume V, the surface tension sigma, and the viscosity eta, of a Cu46Zr42Al7Y5 bulk metallic glass in the molten state were investigated using a...
Zink, Mareike, Samwer, K., Johnson, W. L., Mayr, S. G.
Plastic deformation in metallic glasses well below their glass transition temperatures Tg occurs spatially heterogeneously within highly localized regions, termed shear transformation zones (STZs)....
Room temperature (TR) elastic constants and compressive yield strengths of ~30 metallic glasses reveal an average shear limit gammaC=0.0267±0.0020, where tauY=gammaCG is the maximum resolved shear...
Nucleation is of great concern in many cases—for example, the production of artificial rainfall and the synthesis of advanced amorphous alloys. Although exact solutions have been well known to both...
Surface pinning in an amorphous ZrTiCuNiBe alloy (2005)
Fil, V. D., Fil, D. V., Avramenko, Yu. A., Gaiduk, A. L., Johnson, W. L.
We have measured the amplitude and the phase of an electromagnetic (EM) field radiated from a superconductor (amorphous ZrTiCuNiBe alloy) in the mixed state due to the interaction of the flux lattice...
Mukherjee, S., Schroers, J., Johnson, W. L.
The time-temperature-transformation curves for three zirconium-based bulk amorphous alloys are measured to identify the primary factors influencing their glass-forming ability. The melt viscosity is...
Mukherjee, S., Johnson, W. L., Rhim, W. K.
High-temperature surface tension and viscosities for five bulk metallic glass-forming alloys with widely different glass-forming abilities are measured. The measurements are carried out in a...
Mukherjee, S., Zhou, Z., Schroers, J., Johnson, W. L., Rhim, W. K.
A pronounced effect of overheating is observed on the crystallization behavior for the three zirconium-based bulk metallic glasses: Zr41.2Ti13.8Cu12.5Ni10Be22.5, Zr57Cu15.4Ni12.6Al10Nb5, and...
Surface pinning in amorphous ZrTiCuNiBe alloy (2004)
Fil, V. D., Fil, D. V., Avramenko, Yu. A., Gaiduk, A. L., Johnson, W. L.
We have measured the amplitude and the phase of an electromagnetic (EM) field radiated from superconductor (amorphous ZrTiCuNiBe alloy) in the mixed state due to interaction of the flux lattice with...
Xu, Donghua, Lohwongwatana, Boonrat, Duan, Gang, Johnson, W. L., Garland, Carol
The compositional dependence of a glass-forming ability (GFA) was systematically studied in a binary alloy series Cu100−xZrx (x=34, 36, 38.2, 40 at.%) by the copper mold casting method. Our results...
Shear bands and cracking of metallic glass plates in bending (2003)
Conner, R. D., Johnson, W. L., Paton, N. E., Nix, W. D.
The thickness dependence of yielding and fracture of metallic glass plates subjected to bending is considered in terms of the shear band processes responsible for these properties. We argue that the...
Limited Domain Synthesis of Expressive Military Speech for Animated Characters (2002)
W. L. Johnson, S. Narayanan, R. Whitney, R. Das, M. Bulut, C. Labore
Text-to-speech synthesis can play an important role in interactive education and training applications, as voices for animated agents. Such agents need high-quality voices capable of expressing...
Hays, C. C., Schroers, J., Johnson, W. L., Rathz, T. J., Hyers, R. W., Rogers, J. R., ...
The crystallization kinetics of Zr58.5Nb2.8Cu15.6Ni12.8Al10.3 were studied in an electrostatic levitation (ESL) apparatus. The measured critical cooling rate is 1.75 K/s....
Kim, C. P., Busch, R., Masuhr, A., Choi-Yim, H., Johnson, W. L.
Carbon-fiber-reinforced bulk metallic glass composites are produced by infiltrating liquid Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 into carbon fiber bundles with diameter of the individual fiber of 5 mum....
Pekarskaya, E., Kim, C. P., Johnson, W. L.
In situ straining transmission electron microscopy (TEM) experiments were performed to study the propagation of the shear bands in the Zr56.3Ti13.8Cu6.9Ni5.6Nb5.0Be12.5 bulk metallic glass based...
Schennach, R., Grady, T., Naugle, D. G., McWhinney, H., Hays, C. C., Johnson, W. L., ...
Bulk amorphous alloys are a new class of materials with a variety of characteristics that make them useful for applications in aqueous environments. While some bulk amorphous metals show increased...
Crystallization of amorphous Cu47-Ti34-Zr11-Ni8 (2001)
Glade, S. C., Löffler, J. F., Bossuyt, S., Johnson, W. L., Miller, M. K.
The results of a study on the crystallization of amorphous Cu47-Ti34-Zr11-Ni8 with the use of differential scanning calorimetry, transmission electron microscopy (TEM), x-ray diffraction, field ion...
Bezuglyi, E. V., Gaiduk, A. L., Fil, V. D., Zherlitsyn, S., Johnson, W. L., Bruls, G., ...
The crossing of the temperature dependences of sound velocity in the normal and the superconducting state of metallic glasses indicates renormalization of the intensity of sound interaction with...
Viscous flow of the Cu47-Ti34-Zr11-Ni8 glass forming alloy (2000)
The viscosity of the Cu47-Ti34-Zr11-Ni8 glass forming alloy was determined by beam bending experiments and by a noncontact oscillating drop technique. These viscosity data can be described with the...
Glade, S. C., Busch, R., Lee, D. S., Johnson, W. L., Wunderlich, R. K., Fecht, H. J.
The differences in the thermodynamic functions between the liquid and the crystalline states of three bulk metallic glass forming alloys, Cu47Ti34Zr11Ni8, Zr52.5Cu17.9Ni14.6Al10Ti5, and...
Hays, C. C., Kim, C. P., Johnson, W. L.
Results are presented for a ductile metal reinforced bulk metallic glass matrix composite based on glass forming compositions in the Zr-Ti-Cu-Ni-Be system. Primary dendrite growth and solute...
Bezuglyi, E. V., Gaiduk, A. L., Fil, V. D., Zherlitsyn, S. V., Johnson, W. L., Bruls, G., ...
The crossing of temperature dependencies of sound velocity in the normal and the superconducting state of metallic glasses indicates renormalization of the intensity of sound interaction with...
Sound attenuation in the superconducting amorphous alloy ZrTiCuNiBe (1999)
Bezuglyi, E. V., Gaiduk, A. L., Fil, V. D., Johnson, W. L., Bruls, G., Lüthi, B., ...
The superconducting energy gap and the parameter eta determining the intensity of electron scattering at two-level systems in amorphous ZrTiCuNiBe are determined from the results of measurements of...
Sound attenuation in the superconducting amorphous alloy ZrTiCuNiBe (1999)
Bezuglyi, E. V., Gaiduk, A. L., Fil, V. D., Johnson, W. L., Bruls, G., Luethi, B., ...
The superconducting energy gap and the parameter of the intensity of electron scattering at two-level systems in amorphous ZrTiCuNiBe are determined from the results of measurements of sound...
Hays, C. C., Kim, C. P., Johnson, W. L.
Results of calorimetric, differential thermal analysis, and structural measurements are presented for a series of bulk metallic glass forming compositions in the Zr-Ti-Cu-Ni-Be alloy system. The...
Schroers, J., Busch, R., Masuhr, A., Johnson, W. L.
Isothermal crystallization studies are performed on Zr41Ti14Cu12Ni10Be23 melts between the liquidus and the glass transition temperature. The resulting time–temperature-transformation diagram is in...
Liu, W., Johnson, W. L., Schneider, S., Geyer, U., Thiyagarajan, P.
We report on a small-angle x-ray-scattering (SAXS) and differential scanning calorimetry study of phase separation and crystallization in rapidly quenched amorphous Mg62Cu25Y10Li3 alloy samples....
Masuhr, A., Waniuk, T. A., Busch, R., Johnson, W. L.
The shear viscosity of liquid Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 has been measured. At the liquidus temperature we find an extremely high viscosity of 2.5 Pa s, favoring glass formation. At deep...
Samwer, K., Busch, R., Johnson, W. L.
The change of the compressibility at the glass transition Tg is evaluated from pressure experiments in the liquid and the glassy state of the ZrTiCuNiBe bulk metallic glass forming system. Via the...
Strain Rate Induced Amorphization in Metallic Nanowires (1999)
H. Ikeda, Y. Qi, T. Cagin, K. Samwer, W. L. Johnson, W. A. Goddard, ...
Using molecular dynamics simulations with a many-body force field, we studied the deformation of metal alloy nanowires subjected to various strain rates. For all strain rates, the Ni nanowire is...
Melt infiltration casting of bulk metallic-glass matrix composites (1998)
Dandliker, R. B., Conner, R. D., Johnson, W. L.
The authors describe a technique for melt infiltration casting of composites with a metallic-glass matrix. We made rods 5 cm in length and 7 mm in diameter. The samples were reinforced by continuous...
Choi-Yim, H., Busch, R., Johnson, W. L.
Composites of the Cu47Ti34Zr11Ni8 bulk metallic glass, reinforced with up to 30 vol % SiC particles are synthesized and characterized. Results based on x-ray diffraction, optical microscopy, scanning...
Viscosity and enthalpy relaxation from the amorphous state into the supercooled liquid state was investigated in the bulk metallic glass forming Zr46.75Ti8.25Cu7.5Ni10Be27.5 alloy below the...
Thermodynamics and kinetics of the Mg65Cu25Y10 bulk metallic glass forming liquid (1998)
Busch, R., Liu, W., Johnson, W. L.
The thermodynamics and kinetics of the bulk metallic glass forming Mg65Cu25Y10 liquid were investigated using differential scanning calorimetry and three-point beam bending. The experiments lead to...
Bezuglyi, E. V., Gaiduk, A. L., Fil, V. D., Johnson, W. L., Bruls, G., Luethi, B., ...
The crossing of temperature dependences of the sound velocity in normal and superconducting state of metallic glasses points out unambiguously the renormalization of the intensity of sound...
Bulk metallic glass matrix composites (1997)
Composites with a bulk metallic glass matrix were synthesized and characterized. This was made possible by the recent development of bulk metallic glasses that exhibit high resistance to...
Low-temperature acoustic characteristics of the amorphous alloy Zr41.2Ti13.8Cu12.5Ni10Be22.5 (1997)
Gaiduk, A. L., Bezuglyi, E. V., Fil, V. D., Johnson, W. L.
The temperature dependences of the sound velocity v and attenuation alpha of high-frequency (50–160 MHz) sound in the bulk amorphous alloy Zr41.2Ti13.8Cu12.5Ni10Be22.5 are studied at helium...
Fracture toughness and fatigue-crack propagation in a Zr–Ti–Ni–Cu–Be bulk metallic glass (1997)
Gilbert, C. J., Ritchie, R. O., Johnson, W. L.
The recent development of metallic alloy systems which can be processed with an amorphous structure over large dimensions, specifically to form metallic glasses at low cooling rates (similar to 10...
Collected Papers of the Soar/IFOR Project. Spring 1995. (1997)
Johnson, W. L., Jones, Randolph M., Koss, Frank V., Laird, John E., Lehman, Jill F.
Since the summer of 1992, the Soar/IFR research group has been building intelligent automated agents for tactical air simulation. The Soar/IFOR research project exists at three sites, the University...
Ohsaka, K., Chung, S. K., Rhim, W. K., Peker, A., Scruggs, D., Johnson, W. L.
The specific volumes of the Zr41.2Ti13.8CU12.5Ni10.0Be2.25 alloy as a function of temperature, T, are determined by employing an image digitizing technique and numerical calculation methods applied...
Noncontact modulation calorimetry of metallic liquids in low Earth orbit (1997)
Wunderlich, R. K., Lee, D. S., Johnson, W. L.
Noncontact modulation calorimetry using electromagnetic heating and radiative heat loss under ultrahigh-vacuum conditions has been applied to levitated solid, liquid, and metastable liquid samples....
Oxidation and crystallization of an amorphous Zr60Al15Ni25 alloy (1996)
Sun, X., Schneider, S., Geyer, U., Johnson, W. L., Nicolet, M-A.
The amorphous ternary metallic alloy Zr60Al15Ni25 was oxidized in dry oxygen in the temperature range 310 ±C to 410 ±C. Rutherford backscattering (RBS) and cross-sectional transmission electron...
Geyer, U., Johnson, W. L., Schneider, S., Qiu, Y., Tombrello, T. A.
Be diffusivity data in the bulk metallic glass forming alloy Zr46.7Ti8.3Cu7.5Ni10Be27.5 are reported for temperatures between 530 and 710 K, extending 85 K into the supercooled liquid state of the...
Precipitation of bcc nanocrystals in bulk Mg–Cu–Y amorphous alloys (1996)
Coexistent amorphous and nanoscale bcc-Mg7Li3 phases were found in slowly quenched alloys of the Mg65–xLixCu25Y10 system containing 3 to 15 at.% Li. The crystallization behavior of these alloys has...
Surface microstructure of Zr41.25Ti13.75Cu12.5Ni10.0Be22.5, a bulk metallic glass (1996)
LaMadrid, M. A., O'Connor, S. D., Peker, A., Johnson, W. L., Baldeschwieler, J. D.
The surface of Zr41.25Ti13.75Cu12.5Ni10.0Be22.5, a bulk metallic glass prepared by RF induction melting, has been imaged using atomic force microscopy. The untreated surfaces were very smooth;...
Supercooled melting in multicomponent Zr–Al–Cu–Ni diffusion couples (1996)
Busch, R., Bakke, E., Johnson, W. L.
Diffusion couples combining a hcp Zr90Al10 supersaturated solid solution with a fcc Cu64Ni36 solid solution were annealed at 410 °C for different times. The reaction at the interface was...
Kim, Y. J., Busch, R., Johnson, W. L., Rulison, A. J., Rhim, W. K.
High temperature high vacuum electrostatic levitation was used to determine the complete time–temperature–transformation (TTT) diagram of the Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 bulk metallic glass...
The dynamic compressive behavior of beryllium bearing bulk metallic glasses (1996)
Bruck, H. A., Rosakis, A. J., Johnson, W. L.
In 1993, a new beryllium bearing bulk metallic glass with the nominal composition of Zr41.25Ti13.75Cu12.5Ni10Be22.5 was discovered at Caltech. This metallic glass can be cast as cylindrical rods as...
Schneider, S., Thiyagarajan, P., Johnson, W. L.
Primary crystallization and decomposition in the bulk amorphous alloy Ar41.2Ti13.8Cu12.5Ni10Be22.5 have been studied by small angle neutron scattering (SANS), transmission electron microscopy (TEM),...
Formation of Ti–Zr–Cu–Ni bulk metallic glasses (1995)
Formation of bulk metallic glass in quaternary Ti–Zr–Cu–Ni alloys by relatively slow cooling from the melt is reported. Thick strips of metallic glass were obtained by the method of metal mold...
Bakke, E., Busch, R., Johnson, W. L.
The viscosity of the Zr46.75Ti8.25Cu7.5Ni10Be27.5 bulk metallic glass forming alloy in the supercooled liquid was measured using parallel plate rheometry. The measurements were carried out with...
Geyer, U., Schneider, S., Johnson, W. L., Qiu, Y., Tombrello, T. A.
The self-diffusivity of Be in the bulk metallic amorphous alloy Zr41.2Ti13.8Cu12.5Ni10Be22.5 is investigated. Below the glass transition temperature the data suggest a single atomic jump diffusion...
Decomposition and primary crystallization in undercooled Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 melts (1995)
Busch, R., Schneider, S., Peker, A., Johnson, W. L.
Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 bulk metallic glasses were prepared by cooling the melt with a rate of about 10 K/s and investigated with respect to their chemical and structural homogeneity by atom...
Busch, R., Kim, Y. J., Johnson, W. L., Rulison, A. J., Rhim, W. K., Isheim, D.
High-temperature high-vacuum electrostatic levitation (HTHVESL) and differential scanning calorimetry (DSC) were combined to determine the hemispherical total emissivity epsilon T, and the specific...
Busch, R., Kim, Y. J., Johnson, W. L.
Differential scanning calorimetry (DSC) was used to determine the thermodynamic functions of the undercooled liquid and the amorphous phase with respect to the crystalline state of the...
Kim, Y. J., Busch, R., Johnson, W. L., Rulison, A. J., Rhim, W. K.
Various sample sizes of Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 with masses up to 80 mg were undercooled below Tg (the glass transition temperature) while electrostatically levitated. The final solidification...
A highly processable metallic glass: Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 (1993)
We report on the properties of one example of a new family of metallic alloys which exhibit excellent glass forming ability. The critical cooling rate to retain the glassy phase is of the order of 10...
Search for instability-induced amorphization in deuterated ErFe2 (1993)
Li, J., Yelon, W. B., Johnson, W. L.
Experimental evidence–in the form of a specific-heat anomaly–for instability-induced amorphization of ErFe2 by hydrogenation was recently reported by Fecht, Fu, and Johnson [Phys. Rev. Lett. 64,...
Gibbs free-energy difference between the glass and crystalline phases of a Ni-Zr alloy (1993)
Ohsaka, K., Trinh, E. R., Holzer, J. C., Johnson, W. L.
The heats of eutectic melting and devitrification, and the specific heats of the crystalline, glass, and liquid phases have been measured for a Ni24Zr76 alloy. The data are used to calculate the...
Mechanically driven alloying and grain size changes in nanocrystalline Fe-Cu powders (1993)
Eckert, J., Holzer, J. C., Johnson, W. L.
Highly supersaturated nanocrystalline FexCu100-x alloys (10 less-than-or-equal-to x less-than-or-equal-to 95) have been prepared by mechanical alloying of elemental crystalline powders. The...
Eckert, J., Holzer, J. C., Johnson, W. L.
X-ray diffraction, transmission electron microscopy, and differential scanning calorimetry were used to study the thermal stability of highly supersaturated nanocrystalline FexCu100−x alloys (10
Ohsaka, K., Trinh, E. H., Holzer, J. C., Johnson, W. L.
The heat of fusion and the specific heats of the solid and liquid have been experimentally determined for a Ti60Cr40 alloy. The data are used to evaluate the Gibbs free energy difference, DELTA-G,...
Kittl, J. A., Johnson, W. L., Nieh, C. W.
We have analyzed epitaxial, c-axis oriented YBa2Cu3O7–delta thin films grown in situ by sequential ion-beam sputtering on (100) SiTiO3 and (100) MgO substrates. X-ray diffraction studies showed the...
Fecht, H. J., Perepezko, J. H., Lee, M. C., Johnson, W. L.
The heat capacities of liquid and crystalline Au-Pb-Sb alloys in the glass-forming composition range were measured with droplet emulsion and bulk samples. Based on the measured Cp data, the entropy,...
Kittl, J. A., Nieh, C. W., Lee, D. S., Johnson, W. L.
We have studied the correlations between deposition parameters and structural and electrical properties of YBa2Cu3O7–delta thin films grown in situ by sequential ion beam sputtering. Epitaxial,...
Specific-heat anomaly during vitrification of hydrided Fe2Er single crystals (1990)
Fecht, H. J., Fu, Z., Johnson, W. L.
A solid-state amorphization reaction is observed on hydrided, initially single-crystalline, Fe2Er powder samples (Fe2ErHx, 3.0 < x
Metastable phase formation in the Zr-Al binary system induced by mechanical alloying (1990)
Fecht, H. J., Han, G., Fu, Z., Johnson, W. L.
We have studied the sequence of phase transformations induced in the Zr-Al binary system by mechanical alloying of mixed Zr and Al powders. The structure of these materials has been studied by...
Fecht, H.J., Perepezko, J.H., LEE, M.C., JOHNSON, W.L.
This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying...
Ion mixing of metal/Al bilayers near 77 K (1989)
Ma, E., Workman, T. W., Johnson, W. L., Nicolet, M-A.
The efficiency of interfacial ion mixing is measured for metal/Al (metal=Ti, Cr, Ni, and Mo) thin-film bilayers irradiated with 285 keV Xe + ions near 77 K. The results indicate that, as a group,...
Structural and thermodynamic properties of heavily mechanically deformed Ru and AlRu (1989)
Hellstern, E., Fecht, H. J., Fu, Z., Johnson, W. L.
We report on high-energy ball milling of Ru and AlRu. The deformation results in a drastic decrease of the crystal size to a nanometer scale and in an increase of atomic-level strain. This is...
X-ray diffractometer stage for in situ structural analysis of thin films (1988)
Johnson, R. W., Johnson, W. L.
A theta-two theta x-ray diffractometer stage has been developed for in situ structural characterization of thin-film samples. This stage integrates an ultrahigh vacuum dc ion-beam thin-film sample...
Simultaneous planar growth of amorphous and crystalline Ni silicides (1988)
Ma, W., Meng, W. J., Johnson, W. L., Nicolet, M-A., Nathan, M.
We report a solid-state interdiffusion reaction induced by rapid thermal annealing and vacuum furnace annealing in evaporated Ni/Si bilayers. Upon heat treatment of a Ni film overlaid on a film of...
Nucleation and growth of YBaCuO on SrTiO3 (1988)
Clemens, B. M., Nieh, C. W., Kittl, J. A., Johnson, W. L., Josefowicz, J. Y., Hunter, A. T.
We have studied transmission electron microscopy (TEM) cross sections and plan views of YBaCuO films on SrTiO3 single-crystal substrates at various stages of post-deposition anneal. These TEM studies...
Cotts, E. J., Wong, G. C., Johnson, W. L.
Differential scanning calorimetry and x-ray diffraction are utilized in a study of solid-state vitrification of multilayered composites of Ni and Zr. In order to understand better and optimize the...
Maximum thickness of amorphous NiZr interlayers formed by a solid-state reaction technique (1987)
Meng, W. J., Nieh, C. W., Johnson, W. L.
Formation of the equilibrium intermetallic compound NiZr in sputter deposited Ni/Zr diffusion couples is suppressed by the formation of a metastable amorphous NiZr alloy until a critical thickness of...
Solid-state interdiffusion reactions in Ni/Ti and Ni/Zr multilayered thin films (1987)
Meng, W. J., Fultz, B., Ma, E., Johnson, W. L.
We have performed a comparative transmission electron microscopy study of solid-state interdiffusion reactions in multilayered Ni/Zr and Ni/Ti thin films. The Ni-Zr reaction product was amorphous...
Effect of thermodynamics on ion mixing (1987)
Workman, T. W., Cheng, Y. T., Johnson, W. L.
Ion mixing of elemental 4d-5d metallic bilayers at 77 K by 600 keV Xe + + ions has been studied to test the validity of the phenomenological model of ion mixing that predicts a dependence on the...
From cascade to spike — a fractal-geometry approach (1987)
The fractal nature of collisional cascades in solids is investigated by means of a model of "idealized" collisional cascade and the Winterbon-Sigmund-Sanders theory of atomic collisions. It is shown...
Electron transport in La100-xAlx metallic glasses (1986)
Delgado, R., Armbrüster, H., Naugle, D. G., Tsai, C. L., Johnson, W. L., Williams, Arthur
Values of the electrical resistivity, temperature coefficient of resistivity, thermopower, and superconducting transition temperature for a series of La100-xAlx metallic glasses prepared both as...
Cotts, E. J., Meng, W. J., Johnson, W. L.
We have utilized differential scanning calorimetry to monitor the solid-state reaction of crystalline metals to form an amorphous alloy in multilayered thin-film diffusion couples of elemental Ni and...
Banwell, T., Workman, T. W., Nicolet, M-A., Johnson, W. L.
A correlation between the cohesive energy of elemental solids and the characteristic temperature Tc for the onset of radiation-enhanced diffusion during ion mixing is established. This correlation...
Preparation of amorphous Ti1−xCux (0.10 (1986)
We show that amorphous alloy powders of Cu and Ti can be produced over a broad composition range by mechanical alloying of the elemental powders in a high-energy ball mill. The amorphous powders are...
Internat.Conf.on Rapidly Solidified Materials,
Preparation of amorphous Ti§1§-§xCu§x(0.10 (1986)
Journal of Applied Physics, 60(1986) S.1147-51
Atzmann, M., Unruh, K.M., Politis, C., Johnson, W.L.
Fall Meeting of the Materials Research Society, Boston, Mass., December 1-5, 1985
Refractory amorphous metallic (W0.6Re0.4)76B24 coatings on steel substrates (1985)
Thakoor, A. P., Lamb, J. L., Khanna, S. K., Mehra, Madhav, Johnson, W. L.
Refractory metallic coatings of (W0.6Re0.4)76B24 (WReB) have been deposited onto glass, quartz, and heat-treated AISI 52100 bearing steel substrates by dc magnetron sputtering. As-deposited WReB...
Dominant moving species in the formation of amorphous NiZr by solid-state reaction (1985)
The displacements of W and Hf markers have been monitored by backscattering of MeV He to study the growth of the amorphous NiZr phase by solid-state reaction. We find that the Ni is the dominant...
Electronic structure of amorphous Mo-Ru-Si alloys (1985)
Tenhover, M., Lukco, D., Surman, D., Johnson, W. L.
The results of x-ray photoemission spectroscopy (XPS) and electrical resistivity measurements on amorphous metal alloys of the form (Mo1−xRux)80Si20 are reported. The XPS valence band spectra are...
Correlation between cohesive energy and mixing rate in ion mixing of metallic bilayers (1985)
Van Rossum, M., Cheng, Y-T., Nicolet, M-A., Johnson, W. L.
We have compared the mixing rate of several 5d-4d metal bilayers which form ideal solutions. We observe a strong correlation between the mixing rate and the average cohesive energy of each bilayer. A...
Rutherford, B. D., Hartzler, G. O., McConahay, D. R., Johnson, W. L.
Percutaneous transluminal coronary angioplasty (PTCA) was performed during acute myocardial infarction (AMI) in 105 patients. Catheterisation was carried out from 1 to 24 h (mean 3·8 h) following...
Early stage of crystallization of (Zr1-xHfx)62Ni38 metallic glasses (1984)
Schulz, Robert, Matijasevic, V., Johnson, W. L.
This paper reports a directly observable correlation between the chemical short-range order and the electrical resistivity in metallic glasses. The phase transition corresponding to the first...
Influence of chemical driving forces in ion mixing of metallic bilayers (1984)
Cheng, Y-T., Van Rossum, M., Nicolet, M-A., Johnson, W. L.
The effective interdiffusion coefficient of metallic bilayers under ion irradiation has been correlated with the heat of mixing of corresponding binary alloys. The results are interpreted according...
Amorphization of Hf-Ni films by solid-state reaction (1984)
Van Rossum, M., Nicolet, M-A., Johnson, W. L.
We report on a detailed study of a new process to produce amorphous binary alloys by solid-state reaction of the elemental constituents from an initially thin-layer configuration. The Ni-Hf system...
Structure of glassy early-transition-metal-late-transition-metal hydrides (1983)
Hydrogen is used as a probe for obtaining structural information on metallic glasses. Results from experimental radial distribution functions of hydrided and unhydrided Zr3Rh and Zr2Pd glasses show a...
Formation of an amorphous alloy by solid-state reaction of the pure polycrystalline metals (1983)
Schwarz, R. B., Johnson, W. L.
Single-phase Au1-xLax alloys, with 0.3≲x≲0.5, have been formed through solid-state interdiffusion of pure polycrystalline Au and La thin films (100-600 Å) at temperatures of 50-80°C. The...
The use of metallic glasses in fabrication of ICF targets (1983)
The fabrication of Au-base metallic glass spheres and microballoons used for ICF targets is described. Alloys of composition Au55Pb22.5Sb22.5 were used because of its low melting point and high Z...
Ion mixing to produce amorphous Mo-Ru superconducting films (1983)
Liu, B. X., Clemens, B. M., Gaboriaud, R., Johnson, W. L., Nicolet, M-A.
Amorphous Mo55Ru45 alloy films were formed by ion mixing of multilayered samples. The ion mixed films, which contain no metalloid element, show excellent superconducting properties. The measured...
Yeh, X. L., Samwer, K., Johnson, W. L.
Noncrystalline metallic hydrides can be formed from certain crystalline Zr3Rh intermetallic phases by hydrogenation. X-ray diffraction patterns, density measurements, and superconducting properties...
Superconductivity and the electronic structure of Zr- and Hf-based metallic glasses (1983)
The results of a comprehensive study of the superconducting transition temperatures of Zr- and Hf-based metallic glasses are reported. The microscopic origins of superconductivity in these glasses...
Structural difference rule for amorphous alloy formation by ion mixing (1983)
Liu, Bai-Xin, Johnson, W. L., Nicolet, M-A., Lau, S. S.
We formulate a rule which establishes a sufficient condition that an amorphous binary alloy will be formed by ion mixing of multilayered samples when the two constituent metals are of different...
Surface flux pinning in superconducting amorphous (Mo0.6Ru0.4)B18 (1982)
Clemens, B. M., Johnson, W. L.
Superconducting critical current density was measured as a function of a perpendicular applied magnetic field in glassy (Mo0.6Ru0.4)82B18. The pinning force density was observed to depend linearly on...
Amorphous phase separation in the metallic glasses (Pb1-ySby)1-xAu (1981)
A novel family of ternary superconducting metallic glasses of the form (Pb1-ySby)1-xAux have been prepared by the method of melt quenching and studied by x-ray diffraction and electron microscopy....
Another Look at Dutch Elm Disease Via Digitized Aerial Photography (1981)
Lillesand, T. M., Meisner, D. E., French, D. W., Johnson, W. L.
Previous studies have indicated that crown morphology and within-crown color variations, rather than between-crown color differences, are principal keys to the accurate aerial detection of Dutch elm...
Panissod, P., Aliaga Guerra, D., Amamou, A., Durand, J., Johnson, W. L., Carter, W. L., ...
Through NMR investigation of quadrupolar effects in some amorphous alloys (La75Ga25, Mo70B30, Mo48Ru32B20, Ni78P14B8) the local symmetry is determined around the s-p element sites. A comparison with...
Johnson, W. L., Poon, S. K., Durand, J., Duwez, P.
Results of x-ray diffraction, transmission-electron diffraction, and crystallization studies on amorphous (Mo1-xRux)80P20 alloys obtained by liquid quenching are presented and discussed. The alloys...
Enhanced superconductivity and lattice instability in Nb-Rh alloys (1975)
Superconductivity with transition temperature above 10 °K has been observed in a new Nb-Rh intermediate phase. The new metastable phase is obtained by liquid quenching the binary alloy or by the...
Superconductivity in amorphous and microcrystalline transition–metal alloys (1975)
Results of x–ray diffraction, electrical resistivity, critical magnetic field, and transport measurements for several bulk amorphous and microcrystalline transition–metal superconductors obtained...
Amorphous superconducting lanthanum-gold alloys obtained by liquid quenching (1975)
Johnson, W. L., Poon, S. J., Duwez, P.
Results of x-ray diffraction, electrical resistivity, and critical magnetic field measurements are presented for amorphous superconducting lanthanum-gold alloys obtained by liquid quenching. The...
Superconductivity in metal-semiconductor eutectic alloys (1974)
In an eutectic alloy obtained by melting the constituents, alternating domains of metal and semiconductor can exist in a well-defined microscopic array. The possibility of superconductivity arising...
Low-temperature specific heat of ruthenium (1970)
Measurements of the specific heat of Ru have been performed in the temperature range 2-11.5 K. Values for the Sommerfeld γ and the Debye Θ of 3.10 ± 0.02 mJ/mole K2 and 555±6 K were obtained....
Calorimetric investigation of the antiferromagnetic transition in NiCl2·6H2O (1970)
Measurements of the heat capacity of NiCl2·6H2O were made in the vicinity of the antiferromagnetic transition using calorimetric techniques of sufficient resolution so that the observed behavior was...