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We humans have employed and improved materials for millennia, but it required the Industrial Revolution of the last century to birth the systematic, science-based development of materials. During this time, effort expended in understanding the process-microstructure-properties relationships of materials conferred great economic and military advantage upon the successful. The introduction of machine power in this era created great leverage for improvements in the strength, ductility, corrosion resistance, formability, and similar properties of materials. Response to this opportunity led to the emergence of the materials profession. Stimulated by opportunity, materials scientists and engineers of the day met many of the challenges by first understanding and then controlling the composition and microstructure of materials. In the process, they defined the materials-engineering profession and left their names as a part of its vocabulary: Martens(ite), Bain(ite), Austen(ite), Schmid, Bessemer, Charpy, and Jomminy, to name a few. In fact the understanding and control of microstructure is the hallmark of materials science and engineering. Of course the ancient art of finding, mining, concentrating, and refining materials from the earth's crust does not apply to this definition since we wish to focus on the engineeringofmaterials.Five decades ago, a new chapter in the evolution of this profession began by the invention of the transistor. This invention and the development of integrated circuitry that followed from it spawned a new era of materials achievement, again stimulated by the enormous economic and performance gains available. In this arena however, the object of the game was to completely eliminate microstructure while doing away with impurities, save for a desired few, to levels previously unimagined. Today a material thus prepared is a blank slate upon which we can write the microstructure of an integrated circuit.

The equilibrium structure of [100] oriented steps on the (100) surface of a simple cubic crystal has been examined by Monte Carlo simulation methods. The structures of four surfaces (20,1,0), (10,1,0), (5,1,0) and (100), were simulated and the results combined to determine the properties of an isolated step. The step edge (ledge) energy/length first increases with temperature and then decreases continuously until, at a temperature TR, it vanishes. This temperature, TR, corresponds to the critical temperature for surface roughening, at which the structural and thermodynamic properties of the stepless surface exhibit singularities. These results indicate that TR may be regarded as the temperature above which surface steps may form without increasing the surface free energy. Alternatively, these results show that TR also corresponds to the temperature above which the cusp in a polar plot of surface free energy disappears and the surface becomes nonsingular. e/kTR as determined in this simulation is ∼ 1.57, where e is the strength of the first neighbor bond.

A pair approximation method is described for the interface kinetics of a simple cubic (100) surface with no surface migration. Condensation and evaporation are considered explicitly in a system of master equations applied to a pair of sites; and the effect of the neighboring sites is treated with a set of parameters which are determined self-consistently. Runge Kutta numerical integration of the equations yields the time evolution of the surface. The results for a high entropy of transformation indicate a region of metastable states (zero growth rate) for small driving force, and the instantaneous growth rate is a periodic function of time for larger driving force. The period of the variations is the time required to grow a monolayer, and the amplitude is less than that obtained by Temkin using the mean field approximation. The variations appear as artifacts of most approcimation methods which treat a limited number of sites. The average growth rate is less than the limiting Wilson-Frenkel law for all growth conditions studied. This results since the surface becomes quite rough in the presence of a large condensation rate, and therefore its evaporation rate is greater than the evaporation rate of an equilibrium surface assumed in the Frenkel model. The metastable region is absent at low entropies of transformation and here the growth rate is nearly linear in the driving force. Agreement with Monte Carlo data is excellent for a low entropy of transformation and for all materials at high growth rates.

135 nsec pulses ofλ = 1.06μm light from a Nd: YAG laser have been used to form Schottky barriers by irradiation of a 500A thick metal film on n-type silicon. Large area barriers were fabricated by over-lapping individual 30μ diameter laser pulses of from 4 to 12 J/cm2. The barrier height was 0.73 ± 0.03 V, independent of the laser power. The barrier quality, as assessed by measurement of the forward current characteristic, decreased with laser power to a value of n = 1.5 at 12 J/cm2.

The enhanced grain boundary diffusion in cw laser processed LPCVD polycrystalline silicon films on insulating SiO2 has been investigated and the grain boundary diffusion coefficient D' for Phosphorus has been determined. Mesa diodes were fabricated in the large grain poly-Si films by standard photolithographic and etching methods and subsequent ion implantation. The electron beam induced current mode (EBIC) of the SEM allowed direct measurement of the dopant diffusion length along the grain boundaries intersecting the p-n junction. We have found a t¼ dependence of the penetration depth and Arrhenius behavior for the temperature dependence of the diffusion coefficient. The numerical evaluation of the experimental data is based on Whipple's exact solution of the grain boundary diffusion problem.

Laser annealing of silicon in the pulsed, high energy density mode results in melting and rapid epitaxial resolidification. The incorporation of dopant atoms in the resultant crystals in excess of the retrograde solubility maximum provides firm evidence for the occurence of nonequilibrium, impurity trapping processes at the solid-liquid interface during crystal growth.

Dielectrically isolated single crystals of large extent may be fabricated by zone melting a thin silicon sheet that is encapsulated between SiO 2 layers. The material, however, contains a lineage structure of subgrain boundaries that we demonstrate arises via cellular growth at the trailing edge of the molten zone.

Profound acknowledgment of the importance of materials research to the well-being of society has recently been provided by the government of the United States of America in the form of Public Law 98-373: National Critical Materials Act of 1984. This law provides for the establishment of a National Critical Materials Council within the Executive Office of the President that is responsible for coordination of the government's materials-related policies, programs, and research and technology activities. This new legislation, the major features of which are reproduced on the next page in this issue of the BULLETIN, promises to touch all of us in some way during the coming years.The law establishes a National Critical Materials Council consisting of three presidential appointees who are qualified in materials policy or materials science and engineering. The Council is primarily responsible for the formulation of national materials policies consistent with other Federal policies. This activity includes establishing responsibilities for programs and priorities for materials activities in each Federal department or agency. The Council will also review materials programs and activities of the government for consistency with the National Materials and Minerals Policy Research and Development Act of 1980. It will monitor the critical needs of both industry and government, and it will advise the President of world trends and their implications for national and world economy and national security.

Lasers have long established a permanent position in manufacturing.1–5 They are used to cut hard and brittle materials, to weld metallic objects rapidly and efficiently, to harden locally surfaces of metals, and to drill microscopic holes in materials as diverse as rubber and steel. High power electron beams are routinely used for spot welding and to a lesser extent for cutting and drilling.

The structure of the (110) crystal-vapor or crystal-melt interface of an fcc crystal has been calculated in zeroth order approximation. The results indicate that structural roughening of the interface occurs in the range 0.03 kT / L kT / L . Here L is the enthalpy of vaporization or melting and T is the absolute temperature. The relative population of surface energy levels has also been computed. For kT / L > 0.3, the surface approximates an ideally rough configuration. The surface self diffusion coefficient has been computed from the theoretical distribution of atoms at the interface. The results indicate a positive departure from Arrhenius behavior in the temperature interval where roughening occurs. In the L / kT range encountered in metal-vapor systems the theoretically obtained log ( D s versus L / kT relationship is linear. The departure from linearity commonly observed in fcc metal-vapor system is therefore not predicted to be the result of structural roughening of the (110) orientation surface.

This letter contains some calculations of the thermodynamic properties of lattice model interfaces. The work is compared with that reported recently by Hunt and Gale (see abstr. A16653 of 1974). Their results are shown to be greatly influenced by their restrictive limitation of the interface width.

We have studied the interface between regions of opposite spin in the simple cubic Ising model. Low-temperature expansions of moments of the gradient of the density profile and of the slope at its midpoint suggest that the interface width diverges at a temperature ${T}_{R}$ about half the critical temperature. We discuss the physical significance of this transition and implications for general theories of interfacial properties.

A year ago C. D. Graham Jr. [1] reviewed the behavior and applications of ferromagnetic glasses. This paper will discuss the progress made since that time by a number of investigators in various laboratories. Substantial effort has been directed towards the study of the dynamic properties of these alloys. The dynamic properties examined include the complex permeability and the coercive force as a function of frequency, the rapid flux reversal time as a function of applied field, and the damping associated with domain wall motion. Essentially all of the dynamic properties can be understood by considering the ferromagnetic glasses to be just soft magnetic materials with a resistivity about three times that of permalloy. The details of the domain structure in the two materials differ, but not in a substantial or fundamental way. Because the glassy alloys are in general not isotropic, their domain structure in determined by a local anisotropy which arises due to strain or ’’pair ordering’’.

Metallic glasses undergo structural relaxation at elevated temperatures and their mechanical properties are often dramatically altered as a consequence. We have discovered that the magnetization behavior of a (Ni.5Co.5).75P.16B.06Al.03 glass is similarly sensitive to heat treatment. The ferromagnetic transition in this material is not sharp, and heat treatment serves to broaden the transition further. Tc cannot be defined by conventional methods; e.g., (M)1/β vs (H/M)1/γ plots or a.c. permeability measurements. Both the initial permeability and the high field magnetization increase upon annealing, at rates that are indentical to those of structural relaxation processes. While transmission electron microscopy examination of the glass failed to reveal either crystallization or phase separation, the magnetic properties suggest that a microscopically inhomogeneous distribution of the ferromagnetic species is developed during quenching and heat treatment.

Magnetic properties of metallic glasses in the system (Fe‐Co‐Ni) 0.75 (P‐B‐Al)0.25 have been investigated. Samples were made by the roller quenching technique in the form of ribbons 0.002 in. thick and about 0.125 in. wide. Room temperature saturation magnetization, 4πMs, ranged from a high value of 13,500 Gauss for Fe0.75P0.06Al0.03 to essentially zero for Ni0.75P0.16B0.06Al0.03 which exhibits only weak temperature independent paramagnetism. The highest Curie temperatures occurred in mixed Fe‐Co alloys with a high value of 715°K for (Fe0.4Co0.6)0.75 P0.16B0.06Al0.03. The sign of the magnetostriction was found to change from positive for Fe rich alloys to negative for Co rich alloys so that low or zero magnetostriction composition can be made near the Co rich side of the pseudo‐ternary phase field. For example (Fe0.04Co0.96)0.75P0.16B0.06 Al0.03 has nearly zero magnetostriction. This alloy responds to heat treatment in a magnetic field, developing properties which compare favorably with commercial superma...

Magnetic properties of centrifugal spin quenched ribbons of metallic glasses in the system Fe‐Mn‐P‐B‐Al were studied from room temperature to 1.5°K, with applied fields up to 15.3 kOe. The magnetization vs. temperature curve for (Fe.5Mn.5) .75P.16B.06Al.03 has a broad maximum near 20°K, observed after cooling in zero applied field. Cooling from higher temperatures in the presence of 15.3 kOe applied field, essentially eliminated the broad maximum and established an asymmetrical displaced hysteresis loop at 1.5°K. The intrinsic coercive force was nearly zero on one side, and 7200 oersteds on the other, while the remanence was zero on one side and 3.5 e.m.u./g on the other. Magnetically cycling the field cooled sample several times with ±15.3 kOe at 1.5°K changed the magnetic state of the specimen, resulting in a nearly symmetrical hysteresis loop, with lower coercivity and remanence. Cooling in zero field established a symmetrical hysteresis loop with lower coercivity of ±1600 Oe. Magnetic saturation was n...

The formation of glassy (amorphous) metallic alloys by rapid quenching from the liquid state was discovered in 1960 (1), and subsequent work revealed that certain metallic glasses are ferromagnetic (2). Recently, transition metal based alloys, which possess Curie temperatures as high as 700°K and saturation magnetizations up to 15,000 Gauss, have been shown to be both mechanically very hard and magnetically quite soft (3). We have applied the SEM technique of Fathers et al. (4) as well as electron transmission Lorentz microscopy to a study of roller quenched (5) metallic glass ribbons of composition: TM0.75P.16X.06A1.03, where TM denotes Fe, Co, Ni, or an alloy of these and X denotes either B, C or Si (6).

We have applied the scanning electron microscopy (SEM) technique of Fathers et al. to a study of domain structure in metallic glasses of the form TM0.75P0.16X0.06Al0.03, where TM denotes Fe, Co, Ni, or an alloy of these and X denotes either B, C, or Si. The domain structure is dominated by the presence of a spatially nonuniform uniaxial anisotropy which is related to the flow processes induced by quenching the molten alloy. The existence of both a magnetostrictive and a directional ordering source of anisotropy is indicated.

The magnetic properties of zero magnetostrictive metallic glass have been investigated using both standard fluxmeter methods and domain patterns obtained from a scanning electron microscope technique. This investigation shows that the material is not magnetically isotropic but rather has preferred directions of magnetization that are determined by the details of the quenching process. The magnetic aniostropy produced by subsequent field anneal dominates the original anisotropy and determines the magnetic behavior after the heat treatment.