Publications by Goran Zagar | EPFL Graph Search

Processing and micro-mechanical characterization of multi-component transition MC carbides in iron

Andreas Mortensen, Léa Deillon, Lionel Michelet, Goran Zagar, Marta Fornabaio

We prepare multi-component transition monocarbides of chosen composition by arc-melting together a pre-alloy of the transition metals and cast iron. Based on the elements Ti, Ta, V, Nb and W, 51 different binary, ternary and quaternary compositions are pro ...

2021

In-situ strength of individual silicon particles within an aluminium casting alloy

Andreas Mortensen, Martin Guillermo Mueller, Goran Zagar

Measurements of local strength are performed in-situ on individual silicon particles that constitute the second phase of aluminium alloy A356. Particles are shaped using Focused Ion Beam (FIB) milling such that, upon the application of a compressive force ...

2018

On the diametric compression strength test of brittle spherical particles

Andreas Mortensen, Václav Pejchal, Goran Zagar

Diametric compression testing can be used to measure the hoop strength of spherical particles if one uses platens whose deformation behaviour is tailored in a way that allows the particles to sink sufficiently far into the platens before particle fracture ...

2018

Meridian crack test strength of plasma-sprayed amorphous and nanocrystalline ceramic microparticles

Andreas Mortensen, Václav Pejchal, Goran Zagar, Marta Fornabaio

2018

Compression testing spherical particles for strength: Theory of the meridian crack test and implementation for microscopic fused quartz

Cyril Dénéréaz, Andreas Mortensen, Raphaël Charvet, Václav Pejchal, Goran Zagar

We show that uniaxial compression testing of spherical particles can give unambiguous access to their tensile strength as governed by surface flaws if one uses pairs of elasto-plastic platens, tailoring their hardness in order to control the relative area ...

2017

Stable room-temperature micron-scale crack growth in single-crystalline silicon

Andreas Mortensen, Martin Guillermo Mueller, Goran Zagar

Room-temperature fracture along the (111) plane of silicon is probed at the micron-scale using chevron notched cantilever beams that enable stable crack growth before unstable fracture in successful tests. The main experimental observation is that a growin ...

2017

The local strength of individual alumina particles

Andreas Mortensen, Václav Pejchal, Goran Zagar, Marta Fornabaio

We implement the C-shaped sample test method and micro-cantilever beam testing to measure the local strength of microscopic, low-aspect-ratio ceramic particles, namely high purity vapor grown a-alumina Sumicorundum (R) particles 15-30 mu m in diameter, kno ...

2017

Microscopic strength of silicon particles in an aluminium–silicon alloy

Andreas Mortensen, Martin Guillermo Mueller, Goran Zagar, Marta Fornabaio

A microscopic three-point bending test that measures the strength of faceted particles of high aspect ratio is developed and used to probe individual coarsened plate-like silicon particles extracted from the eutectic Al-12.6%Si alloy. Focused ion beam mill ...

Elsevier2016

Fracture toughness measurement in fused quartz using triangular chevron-notched micro-cantilevers

Andreas Mortensen, Lionel Michelet, Martin Guillermo Mueller, Václav Pejchal, Goran Zagar

We extend to flat surfaces the fracture toughness method presented in Acts Materialia vol. 86 (2015) p.385 and measure in this manner the fracture toughness of fused quartz. Tests give 0.67 +/- 0.01 MPa m(1/2) which agrees with earlier microscopic and macr ...

Elsevier2016

Fracture toughness testing of nanocrystalline alumina and fused quartz using chevron-notched microbeams

Andreas Mortensen, Marco Cantoni, Martin Guillermo Mueller, Václav Pejchal, Goran Zagar

We show that chevron-notched samples offer an attractive approach to the measurement of fracture toughness in micron-scale samples of brittle materials and use the method to characterize quartz and nanocrystalline alumina. Focused ion beam milling is used ...

Elsevier2015

The local strength of microscopic alumina reinforcements

Andreas Mortensen, Marco Cantoni, Andreas Rossoll, Martin Guillermo Mueller, Václav Pejchal, Goran Zagar

We measure, using an adaptation of a method designed for ceramic ball bearings, the local strength of a brittle second phase that serves to reinforce a metal. The method uses focused ion beam milling and a nanoindentation device, and is free of artifacts c ...

Elsevier2015

On measuring fracture toughness under load control in the presence of slow crack growth

Andreas Mortensen, Martin Guillermo Mueller, Václav Pejchal, Goran Zagar, Aparna Singh

The influence of slow crack growth in ceramics on the measurement of their fracture toughness under steadily increasing controlled load (as is generally practiced in microscale testing) is analyzed to identify conditions under which the phenomenon can caus ...

Elsevier2015