Robert Schaller

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Publications associées (31)

Mechanical spectroscopy in carbon nanotube reinforced ABS

Robert Schaller, Daniele Mari

Mechanical spectroscopy has been used to qualify possible improvements of the mechanical properties of acrylonitrile-butadiene-styrene-carbon nanotubes (ABS-CNTs) composites. The properties of ABS matrix are first investigated. Two relaxations that mark th ...

2009

Stress-induced and atomic ordering in 18-carat Au-Cu-Ag alloys

Robert Schaller, Daniele Mari, John Hennig

Atomic ordering and stress-induced ordering (Zener relaxation) were studied in a series of 18-carat (75 wt%) yellow gold alloys (Au-Cu-Ag) by means of isothermal mechanical spectroscopy with a forced torsion pendulum at low frequencies. In the high-tempera ...

2009

Investigation of hydrogen storage in carbon nanotube-magnesium matrix composites

Robert Schaller, Daniele Mari, 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

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

Robert Schaller, Daniele Mari, Abu Salek Md. Fahim Chowdhury

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

Mechanical spectroscopy of 18-carat AuCuPd white gold alloys

Robert Schaller, Daniele Mari, Iva Tkalcec Vâju, John Hennig

The mechanical loss and dynamic modulus temperature spectra of two 18-carat white gold alloys, Au58%Cu24%Pd18% without (grade A) and with alloying additions (grade B), were measured in the 400-1000 K temperature range. A peak interpreted as a Zener relaxat ...

2009

Order-disorder phase transition and stress-induced diffusion in Au-Cu

Robert Schaller, Daniele Mari, John Hennig

Isothermal mechanical spectroscopy by means of a forced torsion pendulum (measuring internal friction/mechanical loss) was used to study the interplay of long-range atomic order and stress-induced diffusion (Zener relaxation) in Au57%Cu43%. Our results sho ...

2009

Influence of the carbon content on dislocation relaxation in martensitic steels

Robert Schaller, Daniele Mari, Ronan Martin

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

Tempering effects on three martensitic carbon steels studied by mechanical spectroscopy

Robert Schaller, Daniele Mari, Iva Tkalcec Vâju

Tempering effects have been studied in three martensitic carbon steels by mechanical spectroscopy. The mechanical-loss spectra present a relaxation peak similar to the Snoek-Koster peak in ferrite. The peak amplitude decreases upon tempering, indicating a ...

2008

Thermal stress relaxation in magnesium matrix composites studied by mechanical spectroscopy

Robert Schaller, Daniele Mari, Abu Salek Md. Fahim Chowdhury

Thermal stress relaxtion at the interfaces in magnesium matrix composite has been studied by mechanical spectroscopy. Two specimens were processed by a gas pressure infiltration method. In one sample, the metallic matrix was unidirectionally oriented with ...

Wiley2008

Etude de la précipitation dans les alliages Al-Ag par mesures de frottement intérieur

Robert Schaller

EPFL1980

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