Publications de Ludger Weber | EPFL Graph Search

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The solid solubility of germanium in silver has been measured in the temperature range of 520 K to 913 K via measurements of density and of electrical conductivity of two near-eutectic Ag-Ge alloys. The atomic fraction of germanium in solid solution varied ...

The influence of partial crystallization on the evolution of the characteristic temperatures, i.e. of the glass transition and the onset of crystallization, the density, and the mechanical properties of the bulk metallic glass Pt(49.95)Si(6)AB(24)Ge(3)Cu(1 ...

Aluminum matrix composites reinforced with mixtures of diamond and SiC particles of equal size were produced by gas pressure assisted liquid metal infiltration. Replacing SiC gradually by diamond particles results in a steady increase of thermal conductivi ...

A simplified model is proposed to quantity the effect of damage in the form of particle cracking on the elastic and plastic behaviour of particle-reinforced metal matrix composites under uniaxial tensile loading: cracked particles are simply replaced, in a ...

Composite materials are often made by infiltration, that is, by injecting a liquid matrix between packed solid fibers or particles. We give here direct proof that molten copper, slowly infiltrated into a broad spectrum of preforms, displays in initial phases of the process universal scaling and fractal geometric features that are characteristic signatures of percolation-dominated flow. Implications are that the microstructure of infiltrated composite materials can develop over length scales that far exceed

Infiltrated particle reinforced composites combine a dense matrix with particles that are in mutual contact and can therefore transfer compressive stress directly from one particle to the next. As a result, these composites may combine characteristics of t ...

An experimental process that was used to obtain a direct measurement of Thermal Boundary Conductance (TBC) between a diamond substrate and several transition metals, deposited by sputtering, is described. Using Time-Domain ThermoReflectance (TDTR), the cri ...

This work probes the influence of wetting on pressure infiltration. Pressure/saturation curves for the infiltration of packed F1000 angular alumina particle preforms by liquid Cu-Al and Sn-Al alloys are measured using an instrumented high-temperature press ...

The aim of the work is to study interface formation between Al2O3 particles and Al(Ca) matrix in dependence of Ca content. Aluminium matrix composites (AMC) subjected to investigation were prepared by gas pressure assisted infiltration of alumina beds with ...

Thermal boundary conductance (TBC) of the Ag/diamond and Au/diamond interfaces with a nanometer-thick interface layer of either nickel or molybdenum is measured by time domain thermoreflectance and modeled based on a 3-layer two-temperature model (3l-TTM). ...

The effect of an Al2O3 interlayer on the thermal conductance of metal (Al)/non-metal (diamond and silicon) interfaces is investigated using Time Domain ThermoReflectance (TDTR). Interlayers between 1.7 and 20nm are deposited on oxygen-terminated diamond an ...

The introduction of new packages as well as the ongoing miniaturization in SMT make the evaluation of the reliability of solder joints a permanent task. Passive thermal cycling is an important test to evaluate the lifetime of solder joints. However, tin-lead solder behaves viscoplastically. Therefore it is mandatory to take the metallurgical behaviour of the solder into account when accelerated tests are designed. Two different deformation mechanisms occur, depending on the temperatures of the test as well

Diamond-based metal matrix composites have been made based on pure Al and eutectic Ag-3Si alloy by gas pressure infiltration into diamond powder beds with the aim to maximize thermal conductivity and to explore the range of coefficient of thermal expansion ...

Drainage curves (plots of the non-wetting fluid saturation versus applied pressure) for infiltration of SiC particle preforms with Al and Al-12.2 at.% Si are measured at 1023 K (750 degrees C) with a pressure infiltration apparatus adapted for direct track ...

There is some confusion in the literature about the material parameters for eutectic tin-lead solder. This is mainly caused by the varying parameters under which the samples are processed and treated prior to testing, which lead to different microstructures. For instance, most investigations are performed with bulk material, some with thin layers. However, the thickness of these layers measures over 100μm; and it is not known whether the material parameters determined on 100μm specimens are appropriate for

A method is presented for studying fibre damage in continuous fibre reinforced composites. It is based on contrasting the transmission of light through intact translucent fibres with the light through fractured or dead-ended fibres. The method is applied in order to detect processing-induced fibre fractures in aluminium reinforced with continuous alumina fibres.

The electrical conductivity of metallic foams varies strongly with porosity. Data are presented for replicated open-pore microcellular metal over a wide range of relative density. These data, together with data from the literature for different foam struct ...

Composite material combining: - a precious metal or an alloy containing a precious metal, - and a boron-based ceramic having a melting point above that of said precious metal and a density at most equal to 4 g/cm3. ...

We report Time-Domain ThermoReflectance experiments measuring the Thermal Boundary Conductance (TBC) of interfaces between diamond and metal surfaces, based on samples consisting of [111] diamond substrates with hydrogen or with sp2 carbon surface terminat ...

Ludger Weber

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Solid solubility of germanium in silver

Effects of partial crystallization in Pt-Si-B-based bulk metallic glasses on glass transition and crystallization of the remaining amorphous matrix

Thermal conductivity of aluminum matrix composites reinforced with mixtures of diamond and SiC particles

Tensile flow stress of ceramic particle-reinforced metal in the presence of particle cracking

Percolation and Universal Scaling in Composite Infiltration Processing

Effect of hydrostatic pressure on flow and deformation in highly reinforced particulate composites

Thermal boundary conductance of transition metals on diamond

Influence of the wetting angle on capillary forces in pressure infiltration

Effect of Ca addition on interface formation in Al(Ca)/Al2O3 composites prepared by gas pressure assisted infiltration

Role of the electron-phonon coupling on the thermal boundary conductance of metal/diamond interfaces with nanometric interlayers

Influence of a Nanometric Al2O3 Interlayer on the Thermal Conductance of an Al/(Si, Diamond) Interface

Lifetime assessment of soft solder joints on the base of the metallurgical behaviour of Sn62Pb36Ag2

Diamond-based Metal Matrix Composites for thermal Management - Potential and Limits

Direct measurement of drainage curves in infiltration of SiC particle preforms

Properties of thin layers of Sn62Pb36Ag2

Transmitted light microscopy of a fibre reinforced metal

The electrical conductivity of microcellular metals

Composite material comprising a precious metal, manufacturing process and use of such a material

Qualitative link between work of adhesion and thermal conductance of metal/diamond interfaces

Non-conducting inclusions in a conducting matrix: Influence of inclusion size on electrical conductivity