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Soft tribological coatings deposited by magnetron sputtering are used as protective layers of sliding bearings in high‐performance diesel engines. They consist of a tough component with a high melting point and a soft component with a low melting point. The tough component gives mechanical stability while the soft component provides the capability to embed contamination particles. The components are immiscible to prevent the formation of intermediate brittle phases. One system under investigation is copper lead. Although the chemical composition of a sputter‐deposited film should generally be equal to target composition this does not hold for Cu with a small amount of Pb. The experiments showed that the Pb content of films deposited by magnetron sputtering with Ar+ ions from a planar‐cast Cu 4 wt % Pb target strongly depends on the process parameters of working gas pressure and substrate temperature. Gas pressure and substrate temperature were varied from 0.3 to 5 Pa and 100 to 260 °C, respectively. The P...

The finite element program MARC® serves as a convenient tool to simulate microhardness testing procedures on a wide range of homogeneous and inhomogeneous materials, and an unlimited variety of indenter shapes. The items considered are: (i) imprints with wedge shaped bodies into coated samples (two-dimensional problems). (ii) Imprint with a Vickers indenter into a homogeneous sample (a three-dimensional problem). For microhardness testing simulations, the program was prepared to deal with the decision as to whether a material is cut through by the indenter or just embossed. The investigations reveal the possibility of calculating the Vickers hardness of any combination of isotropic materials, coated or uncoated, from mechanical properties derived from uniaxial tensile tests.

Detailed studies of TiN coatings deposited either by hollow cathode evaporation or by ion sputtering onto high speed steel have been performed. Phase identification, texture and profile analysis were carried out from X-ray diffraction data. A series of stable and unstable phases were found. The (111) texture was dominant in all cases. Dislocation density and configuration were determined by X-ray profile to give an estimate of coating hardness.

We evaluated ion plated and, for comparison, electron beam evaporated thin films with an ultra-microhardness tester used with an optical microscope. Implementations of the instrument for use inside a scanning electron microscope1,2,3 and with a high resolution optical microscope4 have been described in sufficient detail elsewhere. Figure 1 shows typical indentations made with a Vickers diamond in a rather thick ion plated single layer of TiO2 in comparison with an indentation obtained in an electron beam evaporated film of the same material and similar thickness. The ultra-microhardness values resulting from the measurement of the imprint diagonal differ whether the indentations are observed and measured with an optical microscope or with a scanning electron microscope.

A state-of-the-art finite element program (MARC TM ) is used to derive as much information as possible from the simulation of a 136 degree(s) wedge indentation into multilayer systems. The deformed specimen is compared with experimentally found results as far as an experiment, i.e., a hardness indentation, yields measurable parameters. We suppose some of the surplus information obtained by the simulation to be reliable as well. A first step is undertaken toward the aim of obtaining elastic constants from a hardness or load-depth measurement in multi-phase films.

The NdxFe1-x amorphous thin films with x=0.06-0.80 were prepared at 77 K by flash evaporation. The results show that the amorphous films are stable at room temperature when 0.192 and T untill the crystallization occurs. The crystallization of the amorphous films can not be completed at a certain fixed temperature but over a temperature range.

The magnetic properties are reported for amorphous NdxFe1-x films prepared by flash e-vaporation at 77K. The result indicates that Nd is nearly random distributed with a small net moment parallel to the Fe moments which posseses a ferromagnetic alignment. The distribution angle of the Nd-atomic moments increases slightly with increasing x. The ordering temperature Tc is dependent on applied field and the values of Tc from Arrott-plot or other evaluation methods are different. This can be attributed to exsistence of clusters with different Tc in the film. The exchange interaction, but not the spontaneous magnetisation, is strongly influenced by the preparation conditions.

Simultaneous grain boundary-, surface- and lattice diffusion in hypothetical thin film couples of miscible components was computer simulated. On this basis the diffusion into fixed and moving grain boundaries is discussed with respect to the determination of diffusivities by depth profiling methods. The data evaluated from the synthesised depth profiles according to Whipple-Le Claire as well as to Gilmer and Farrell were compared with the diffusivities used for the computation. Agreement was found for systems with a fixed grain boundary network. Moving grain boundaries, however, may cause errors of an order of magnitude towards lower grain boundary diffusivities

In thin film couples consisting of a 200 A Allayer upon un Ag film of 400 a, diffusion and phase growth were investigated by means of an X-ray optical depth profiling method, making use of the Kiessig interference pattern. Films annealed at 80, 90, 100 and 110°C were examined in subsequent stages of mixing. Mean diffusion coefficients ranged from 10−15 to 10−14cm2s, associated with an activation energy of 25 kcalmol. The alloying process has been identified as the growth of Ag2Al out of the rapidly saturated grain boundary network in addition to the direct growth parallel to the interface. Alloy formation starts with a temperature dependent delay, typical for Ag2Al precipitation.

Gold and its compounds Au2Al, Au5Al2 show marked differences in their spectral reflectivity in the visible range. These differences, observable with the naked eye, have been used to detect the approach of the phase front of diffusionally grown compounds against the gold surface of a Au-Al thin film couple. From a continuous sequence of such couples evaporated in different thicknesses onto the same substrate, i.e. a step-shaped diffusion couple, of a total atomic ratio 2Au/Al, the growth rate constants were obtained The temperature for the diffusion anneal ranged from 333 to 373 K. Excellent agreement with recent literature data for the rate constants was found only in the thicker part of the couple : D=2.1 exp(-1/kT)cm2/s whereas the thinner part showed slightly higher rates.

In order to separate diffusion induced changes in the electrical resistivity of quench-condensed amorphous AgCu alloy films from such arising from other causes several trial experiments have been performed. Such films consisting of alternating Ag60Cu40/Ag40Cu60 layers showed a specific resistance rise which revealed the following peculiarities: 1. The duration of this increase is inversly proportional to the square of the individual Ag60Cu40/Ag40Cu60 couple thickness, 2. The increase is suppressed if rapid heating up to the crystallization temperature is performed and 3. It is not appearing in homogeneous layers. These results give clear evidence that the observed effect is arising from diffusional intermixing only. Diffusion coefficients averaged over the annealing period are estimated as D = 8.7 x 10-15 cm2s-1 x exp 0.89 eV/kT.

A short literature survey on the subject is given with special emphasis on discrepancies and contradictional interpretations of results. Our own experiments on thin copper films evaporated onto glass substrates at different condensation temperatures are reported. Density values were calculated from the film thickness, which was measured by Kiessig's method and from the deposited mass determined by atomic absorption spectrometry as well as gravimetric measurements. The density defect decreases with increasing film thickness, as already established, and also with temperature. From these results together with those obtained from films which were deposited during a rapid temperature rise from the low substrate temperature to room temperature we conclude that the density defect is localized at the substrate - film boundary.

The change of x-ray optical properties during diffusional alloy formation can be used for the evaluation of diffusion parameters in bimetallic thin film couples. The most pronounced phenomenon governed by these properties are the known Kiessig interferences which can be observed in the specular scattered x-ray beam at very small glancing angles. From these interference patterns diffusion data can be obtained by a comparison with calculated reflection curves based on a proper model for diffusion. The most useful thickness range for this method is below 1000 Å, where common x-ray techniques lose their applicability. Since the changes in the interference patterns are most significant in the early diffusion stages, this technique is most suitable for observing initial interdiffusion, which very often occurs with enhanced diffusion rates. The experimental check of the method is performed in the Au-Ag system. Bimetallic films of the pure components were annealed at temperatures between 200 and 300 °C. In this temperature range diffusion parameters from 10-16 to 10-14 cm2/s were found in good agreement with values obtained by other techniques.

Imaging of Vickers imprints for in situ hardness test of insulating samples in a scanning electron microscope requires a conductive surface layer to avoid charging. The influence of such coatings on the measured hardness and the elimination of this effect by an extrapolation towards zero thickness of the layer are discussed theoretically. The method is checked by the example of gold-coated silicon