Some unrelated examples are given where progress has been made in laser surface treatment in the last few years. These are large scale transformation hardening, reproducible surface melting of cast iron, surface alloying with a reaction with the surrounding atmosphere, fundamental studies of solidification and evaporation cleaning.

High-silicon steel was rapidly solidified to thin strips by the double roller method. Two typical macrostructures were observed: one with an equiaxed zone and the other without. The formation of the equiaxed zone is caused by an excessive gap between the rollers. Heat transfer calculations and dendrite arm syacing measurements both suggested that the cooling rate is about 103 to 104 K/sec.

A new melt-spinning technique (field quenching) for ferromagnetic amorphous ribbon is suggested to produce better magnetic properties than conventional as-quenched amorphous ribbon. An external field is applied during the quenching either parallel or perpendicular to the casting direction. The magnetic moment and initial permeability are increased when the field direction is parallel to the casting direction. These effects are opposite when these two directions mentioned are perpendicular to each other.

A single roller technique called melt overflow for direct casting metallic sheet, strip or foil is described. A simiple heat transfer nodel is developed to predict foil thickness frorn process parameters. The model agrees with thickness of Ti-6Al-4V cast strip. Cooling rates as high as 105 K/s are estimated from measuremnents of secondary dendrite arm spacings in 7075 aluminum alloys. Applications include magnesium-graphite composites.

We report the formation of single-phase amorphous Cu-Er and Ni-Er alloys in bulk form by cold-rolling of composites prepared from elemental foils. As for previously reported cases of metallic glass formation by solid-state reaction, the driving force for the reaction is the negative enthalpy of mixing of the constituent elements. It occurs during deformation close to room temperature. Amorphous Cu7 2 Er2 8 was also produced by high-energy ball-milling of the elemental powders as well as by sputtering and liquid quenching. The alloys obtained were characterized by means of differential scanning calorimetry and x-ray diffraction. The crystallization behavior observed and the radial distribution functions obtained showed good agreement between the alloys prepared by different methods.

TiN films lμm thick were deposited on SKH55 alloy substrate at various substrate bias voltage by a reactive sputtering of Ti target in a mixture of Ar (1 mTorr) and N2 (1 mTorr) with a Target Facing type of high rate sputtering apparatus. The color of the film changes in the order of yellow, golden, silver and golden as the substrate bias voltage increases from 0 to 200 V. The reflection ratio and Vicker's hardness of the film also changes with the bias voltage. Besides, the change of the reflection factor corresponds well to the change of theVicker's hardness of the film. The films with silver color and maximum reflection ratio which are obtained at a rf bias voltage around 100 V, have the largest value of the Vicker's hardness about 3500. While, the films with golden color and small reflection factor, which are obtained at both rf bias voltage around 80 V and 150 V, have the lowest Vicker's hardness of about 1500.

Magnetic thin films (Co-Ta, Co-Zr and pure iron films) have been deposited by means of dual ion beam sputtering and the effect of bombardment of high energy ions onto growing surface on their structure and properties has been investigated. The bombardment of argon ions with proper kinetic energy has the effects as follows;I. suppression of growth of crystallites, II. improvement of structural ordering in micro-scale and III. improvement of structural uniformity in macro-scale. Therefore, the films deposited with the proper bombardment are composed of fine crystallites with good atomic ordering. This causes an increase of 4лMs and reduction of Hc of the films;Co-Zr:4лMs=16 kG, Hc<0.6 Oe, Co-Ta:4лMs=15 kG,Hc<0.3 Oe and iron films:4лMs=21 kG,Hc=l Oe.

Microstructural transitions occurring during solidification processes may be described in terms of three dimensionless parameters, s, p and σC, which include among them various processing variables and relevant material constants. The dimensionless parameter, s, in particular offers a convenient description of both planar-cellular and cell-dendrite transitions. The relationships between σC, s and p predicted by various dendrite growth models have been summarized.

Recent developments in theory and experiment seem to enable us to relate the electronic structure to the formability of glassy states in transition metal-metalloid base alloys. Especially stressed is the role of the antibonding states in the glass formation.

Ti-Ni-Al alloys were rapidly quenched from a molten state by the melt spinning method. Three kinds of metastable phases, namely, amorphous,nonequilibrium and quasicrystalline phases are formed in these alloys. The amorphous phase is formed in the range of 35 to 70 at% Ti and 0 to 25 at% Al. The nonequilibrium phases are formed in the composition range of 25 to 33 at% Ti. On the other hand, fine quasicrystalline phases are distributed in the amorphous matrix of the Ti-rich alloys. Crystallization temperatures and the hardness of the amorphous alloys were also examined.

The kinetics of amorphous phase formation in polycrystalline A1–xBx (A=Zr, Hf, B=Pd, Rh,.15<x<.25) alloys during reaction with hydrogen has been studied by x-ray diffraction, +19F nuclear reaction depth profiling, TEM and electron diffraction. The formation of the amorphous hydride phase is observed by TEM to begin at grain bounderies of the polycrystalline Zr1–xRhx much in the same manner that “melting” nucleates at grain boundaries. TEM micrographs further show that the phase boundary between the crystalline and amorphous phases remains sharp during the growth of the amorphous phase. Both x-ray diffraction and nuclear depth profiling studies suggest that the overall rate of transformation to the amorphous hydride phase is limited by the rate of hydrogen permeation through the sample surface.

Based on the present experiments and an analysis of the relevant free energy curves, we discuss the thermodynamic and kinetic aspects of this effect to explain why an amorphous phase is formed.

Amorphous compositionally modulated films of Cu-Zr and Fe-Ti have been prepared by sequential sputter deposition of the elemental metals. For Cu-Zr, a critical modulation amplitude has been found, below which the samples are entirely amorphous. The effective interdiffusion coefficient during deposition has been estimated, and found to be assisted by the free energy of mixing and the ion bombardment. X-ray studies of the modulation peaks, using grid scans, reveal a sharp mosaic, and asymmetrical peaks in some samples.

Fe-Si, Co-Ta and Co-Zr amorphous films have been deposited by using various sputtering methods (conventional rf diode sputtering, rf triode sputtering, dc Targets Facing type sputtering (dc TF sputtering) and dual ion beam sputtering (DIB sputtering)). The lower limit of the Si and Ta content to form amorphous Fe-Si and Co-Ta films changes significantly with the sputtering method. These differences between the sputtering methods are mainly caused by the differences in the plasma potential which affects the amount of ion bombardment to the film surface during sputtering,and the minimum content of Si or Ta to obtain amorphous films decreases as the plasma potential increases. These results indicate that the ion bombardment suppresses the growth of crystallites and promotes the formation of the films with amorphous structures. This is confirmed by the deposition of Co-Ta and Co-Zr amorphous films under the condition of various amount of ion bombardment by using a DIB sputtering system.

We present results on structural relaxation in Fe-B glasses. Relaxation effects were studied through measurements of the Curie temperature (Tc) of the glasses annealed at different temperatures (Ta). We observe a monotonic increase in Tc with Ta in all alloys due to irreversible structural relaxation. This increase continues till the start of surface/ bulk crystallization. The observed decrease in Tc upon further annealing is attributed to the strain introduced in the partially glassy system. We see no evidence for reversible structural relaxation in Fe-B glasses.

In this paper we report the difference in the structures, physical properties and thermal behaviors of two compositions of amorphous Hf-Cu. One (Hf50CU50) is near the eutectic composition and the other (Hf67Cu33) corresponds to an intermetallic compound. Transmission and scanning electron microscopy (TEM, SEM), differential scanning calorimetry (DSC), electrical resistivity and high-angle X-ray diffraction have been used to study these glasses in detail. Amorphous Hf67 Cu33 is structurally stable up to the crystallization temperature, while Hf50 Cu50 undergoes a ductile to brittle transition associated with a chemicai phase segregation at temperatures far below the glass transition. An anomalous behavior in the resistivity is associated with this phase transformation.

The crystallization of rapidly solidified Zr-Ni metallic glasses has been studied by differential scanning calorimetry (DSC), x-ray diffraction (XRD), and transmission electronmicroscopy (TEM). Evidence has been found for a metastable phase which is the first crystalline phase to form upon heating in compositions of 57 to 63.2 at. % Zr. This phase seems to be more easily formed and is most stable in the region of 58 to 59 at. % Zr. Uponsubsequent heating to higher temperatures, the metastable phase transforms to the equilibrium phases ZrNi and Zr2Ni. The relationship of this new phase to phase separation at the eutectic composition of 63.5 at. % Zr is discussed in support of the conclusions drawn from low temperature specific heat studies reported previously [1,2].

Amorphous and partially crystalline Fe7 8B1 3 Si9 alloys have been examined by high resolution transmission electron microscopy at 200kV. In lattice imaging mode, the as-quenched alloy shows small regions, with a mean size of - 20Å, consisting of well defined patterns of fringes. Three different types of crystals can be identified at the very earliest stages of crystallisation of the alloy.

The kinetics of bcc crystallization and subsequent transformations in an Fe43Cr25Ni20B12 glass were monitored by magnetic measurements and X-ray diffrsaction. The metastable bcc phase (ferrite) which forms first transforms to austenite and a boride during isothermal annealing. At low temperatures the ferritegrows without significant partitioning of Fe, Cr and Ni. Increasing the annealing temperature results in alloy partitioning which is directly linked with the ferrite decomposition.

In order to elucidate the sensitivity and information that can be obtained from Magneto-Thermo-Gravimetric, MTG, technique, we present a comparative study of our results on structure relaxation as well as crystallization sequences as a function of time and temperature of amorphous Fe90-xSixB10 alloys in the Fe-rich regime, with those obtained from synchrotron Energy-Dispersive- X-ray-Diffraction, EDXD, and Differential Scanning Calorimetry, DSC methods.

Thin amorphous metal ribbons can be bonded together to form a thick strip which remains amorphous. This, PowercoreTM strip, has similar magnetic properties to the annealed thin ribbon and so is a direct substitute for silicon steel in power transformers. Its good properties are partially a result of the nature of the bond between the layers of ribbon. This paper reports on a study of this bond by Auger microscopy and laser acoustic microscopy.