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The bonding energies of surface atoms of intermetallic compounds were computed to predict qualitatively a selective field evaporation of one atomic species under typical conditions for field-ion microscopy. It was assumed that atoms with smaller bonding energies will be eliminated selectively during field evaporation. Comparison of calculations with those of other models indicated that neither conventional selective field evaporation nor the charge transfer can elucidate on all the observations.

A model is derived to study the change in acoustic nonlinearity due to the interaction of matrix dislocations with precipitate coherency strains in metallic alloys. It is shown that the acoustic linearity parameters are dependent on dislocation intensity, precipitate-matrix misfit parameters, volume fraction of precipitates and fourth power of the dislocation loop length. Model and experimental results also showed good agreement.

Several techniques were utilized to examine low-temperature molecular beam epitaxy of Ge-rich Ge-Si-C alloys grown on Si(100). These include in situ reflection high-energy electron diffraction, transmission electron microscopy, Raman scattering, ellipsometry and ex situ x-ray diffraction. Results showed that increasing C concentration decreases lattice parameter. No systematic changes were observed at the Ge-Ge mode.

The probability theory is applicable in studying the kinetics of phase transformations in alloy systems wherein the diffusion of solute atoms is a controlling factor. The rate of diffusion-controlled growth allows scientists to examine the impact of overlapping diffusion zones. 'Soft impingement' only becomes a controlling variable during the last stage of the phase transformation.

Linear and nonlinear perturbation analyses help examine the morphological stability of the solid-liquid interface in dilute binary alloy solidification and incorporate the effects of excess enthalpy in the condition describing the local energy balance at the solid-liquid interface. A direct method of undetermined coefficients helps calculate the Landan coefficient representing the nonlinear growth rate. The excess-energy correlation is significant at large growth velocities and low frequencies of interface perturbation in metallic and nonmetallic systems.

Raman spectroscopy techniques measure the alloy composition and strain value in thin Ge(x)Si(1-x) layers at 200 A. Different methods of studying Raman spectra, including the composition measurement from the strain independent Ge-Ge to Si-Si mode ratio, are developed. The new techniques enhance parallel and perpendicular spatial resolution, enabling transport data interpretation and multilayered structure analysis.

Amorphous rare-earth-transition-metal (RE-TM) alloys containing Pr, Nd, Fe and Co are prepared by coevaporation and their magnetic and magneto-optical properties are analyzed with respect to their compositional behavior. RE and TM influence the-magneto-optical properties, and at high temperatures, TM has more influence. The Faraday and Kerr relations for Pr-TM and Nd-TM alloys are larger for temperatures below the curie temperature.

Thermal oxidation of polycrystalline Ge(sub x)Si(sub 1-x) and pseudomorphic GeSi at a favorable temperature ranging from 550 to 900 degrees centigrade reveals that backscattering spectrometry of the high Ge content has a uniform Ge(sub x)Si(sub 1-x)O2 layer. The Si(sub 1-x) layer is produced at high temperatures when the Ge content is very low. The formation of Si(sub 1-y)O2 layer piles up the Ge behind the oxide layers.

The qualities of the superconducting transition of metallic nanocomposites maintaining superconducting grains dispersed in a metallic matrix is discussed. Rapid quenching techniques were used to prepare and characterize the nanocomposites of Al-In, Al-Pb and Zn-Pb as resistivity measurements were used to monitor the nature of superconducting transitions in them. The domination of the observed transition curve was established.

Mechanical alloying and milling process help analyze the permanent magnetic properties of isotropic and anisotropic powders of 1-12 nitrides of Nd and Pr. X-ray-diffraction and thermomagnetic studies on isotropic powders indicate the dependence of coercivity on crystallization temperature, while in anisotropic powders, particle size affects coercivity. All mechanical alloy powders are isotropic. Replacement of Mo with Ti or V in these magnetic nitrides increases their thermal stability.

Coarse powders of Sm2(Fe,V)17Ny alloys show high coercivity (HcJ) 342 kA/m with a particle size of 20-74 micrometers. The microstructures of the powder grains in possibly the cause of the high HcJ value. Nitrogenation of these alloys results in expanded crystal lattice. Structures of the alloys are of Th2Zn17, TbCu7 or ThMn12 type depending on the vanadium content.

The F-thermal annealing method was applied to nanocrystalline amorphous Vitrovac 6025 metallic alloy samples in the temperature range 576 to 716 K for 10 to 90 minutes. The domain wall relaxation frequency and initial magnetic permeability were estimated and expressed on the basis of free wall surface area between the pinning sites and the dependence of wall bulging on anisotropy. The crystalline size up to 60 minutes annealing time was measured by transmission election microscopy.

Two magnetic phase transitions are exhibited by the noncollinear hexagonal antiferromagnet, UPdSn, at 35 and 23 K, respectively. The transition to a noncollinear antiferromagnetic state from a hexagonal paramagnetic state occurs at 35 K. The transition at 23 K is caused by the monoclinic magnetic structure of the material. The transition indicates that the moment components are caused by fluctuations.

Magnetic measurements of amorphous Co(sub 1-x)Er(sub x) ribbons fabricated by melt-spinning methods reveal that the ribbons cannot be magnetized completely. This is due to the spheromagnetic spin structure of the ribbons provided by the moment of Er. The Co moment has no influence on the process of magnetization.

A band-gap database of a large number of configurations is produced for AlGaInP semiconductor alloys by using an empirical pseudopotential method. The results have shown that a majority of alloy configurations have band gaps smaller than those predicted by VegardEs law and also many trends are shown in the band gaps depending on the superlattice directions

It is shown from general statistical calculations that a relatively simple analytical relation can be obtained for the temperature dependence of the segregation stabilised boundary fraction. The validity conditions of the relation proposed very recently by R. Kirchheim are also analysed.

The alloy structures that can evolve in nonequilibrium driven systems, using two-dimensional atomistic simulation of mechanical alloying is explored. Molecular static simulations of mechanical alloying is performed and the results of the simultaneous capture many of the interesting structural transitions known in mechanical alloying experiments.