Robert Schaller

Cette personne a quitté l’EPFL

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Publications associées (30)

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High temperature mechanical spectroscopy of fine-grained ceramics

Robert Schaller, Claudia Ionascu

Mechanical loss measurements were performed at high temperature in fine-grained ceramics, such as zirconia and alumina. At high temperature, the mechanical loss increases exponentially with temperature, which accounts for material creep. The results are an ...

2009

Investigation of hydrogen storage in carbon nanotube-magnesium matrix composites

Daniele Mari, Robert Schaller, Iva Tkalcec Vâju

Magnesium (Mg) and magnesium nickel (Mg-23.5 wt%Ni) reinforced with multiwalled carbon nanotubes (CNTs) were processed by powder metallurgy and then charged with hydrogen by annealing at 620 K under a pressure of 0.4 MPa of hydrogen. Mechanical spectroscop ...

2009

Influence of the carbon content on dislocation relaxation in martensitic steels

Daniele Mari, Robert Schaller

Mechanical-loss measurements were performed in three grades of martensitic high-carbon tool steels. These steels were treated under carburizing gas before quenching, in order to vary the concentration of interstitial carbon in the martensite, as assessed b ...

2009

High temperature mechanical loss spectrum of 3Y-TZP zirconia reinforced with carbon nanotubes or silicon carbide whiskers

Robert Schaller, Claudia Ionascu

High temperature plasticity of fine-grained ceramics (ZrO2, Al2O3, etc) is usually associated with a grain boundary sliding process. The aim of the present research is then to improve the high-temperature mechanical strength of polycrystalline zirconia (3Y ...

Trans Tech Publications Ltd, Laublsrutistr 24, Ch-8717 Stafa-Zurich, Switzerland2008

Grain boundary formation stages in a deformed yellow gold single crystal studied by mechanical spectroscopy

Daniele Mari, Robert Schaller, Iva Tkalcec Vâju, Ann-Kathrin Audren

A monocrystalline 18-carat yellow gold sample is deformed stepwise from 2% to 12% at room temperature. The mechanical loss spectrum is recorded and analysed. At low deformations the exponential high temperature background increases. At a critical deformati ...

Elsevier Science Sa2013

High temperature mechanical spectroscopy of yttria stabilized zirconia reinforced with carbon nanotubes

Daniele Mari, Robert Schaller, Mehdi Mazaheri

High temperature mechanical properties of zirconia reinforced with carbon-nanotubes (CNTs) are studied by mechanical spectroscopy. CNTs limit zirconia grain-boundary sliding (GBS) and consequently deformation. Concurrent grain-growth and plastic deformatio ...

Wiley2010

Recrystallization and grain boundary formation in an 18-carat gold alloy studied by mechanical spectroscopy

Daniele Mari, Robert Schaller, Iva Tkalcec Vâju, Ann-Kathrin Audren

Heavily deformed 18-carat yellow gold samples show a recrystallization peak at 700 K during the first heating. The mechanical loss spectrum of polycrystals shows a relaxation peak at about 780 K, which is absent in single crystals made from the same alloy. ...

Trans Tech Publications Ltd2013

Analysis of transient mechanical loss due to thermal stresses in metal matrix composites

Daniele Mari, Robert Schaller

Mechanical spectroscopy has been used to study the thermal stress relaxation at the interfaces in magnesium matrix composites. The mechanical loss spectra measured as a function of temperature show an intrinsic component superimposed on transient damping. ...

2009

Thermal stress relaxation in magnesium matrix composites controlled by dislocation breakaway

Daniele Mari, Robert Schaller

In metal matrix composites (MMCs) thermal stress relaxation can be achieved either by interface debonding, crack propagation or by dislocation motion. The present paper shows that in the case of magnesium matrix, interface thermal stresses are relaxed by d ...

2010

Grain boundary relaxation in yellow gold bi-crystals

Daniele Mari, Robert Schaller, Iva Tkalcec Vâju, Ann-Kathrin Audren

The mechanical loss spectrum of a yellow gold bi-crystal is presented and analyzed in detail. The relaxation strength is monitored as a function of several geometrical parameters such as sample width, length and thickness. It is found that the relaxation s ...

Elsevier2015