Publications by Helena Van Swygenhoven

Operando X-ray diffraction study of thermal and phase evolution during laser powder bed fusion of Al-Sc-Zr elemental powder blends

Elemental powder blends are an emerging alternative to prealloyed powders for high-throughput alloy design via additive manufacturing techniques. Elemental Al+Sc(+Zr) powder blends were processed by laser powder bed fusion into Al-Sc and Al-Sc-Zr alloys, w ...

2022

Direct observation of crack formation mechanisms with operando Laser Powder Bed Fusion X-ray imaging

Eric Boillat, Jamasp Jhabvala, Helena Van Swygenhoven, Roland Logé, Samy Hocine, Hossein Ghasemi Tabasi, Navid Sohrabi

Laser powder bed fusion (L-PBF) is a versatile additive manufacturing process that can print geometrically complex metal parts for a variety of applications. However, poor control of defect formation during processing hampers its widespread industrial adop ...

ELSEVIER2022

Deciphering the interactions between single arm dislocation sources and coherent twin boundary in nickel bi-crystal

Helena Van Swygenhoven

The introduction of a well-controlled population of coherent twin boundaries (CTBs) is an attractive route to improve the strength ductility product in face centered cubic (FCC) metals. However, the elementary mechanisms controlling the interaction between ...

Nature Research2021

The effect of stress triaxiality on the phase transformation in transformation induced plasticity steels: Experimental investigation and modelling the transformation kinetics

Helena Van Swygenhoven, Efthymios Polatidis, Nicola Casati

In situ multiaxial loading during neutron diffraction tests were undertaken on a low-alloyed Quenched and Partitioning (Q&P) Transformation Induced Plasticity (TRIP) Bainitic Ferrite (TBF) steel with dispersed austenite particles. The effect of stress tria ...

2021

Verification of selective laser melting heat source models with operando X-ray diffraction data

Helena Van Swygenhoven, Steven Van Petegem, Samy Hocine

The output obtained from operando X-ray diffraction experiments on Ti-6Al-4V is used to verify the accuracy of four FEM models in predicting the temperature evolution of the solidified domain, the cooling rates of the alpha and beta phases, and the influen ...

ELSEVIER2021

Additive micro-manufacturing of crack-free PDCs by two-photon polymerization of a single, low-shrinkage preceramic resin

Helena Van Swygenhoven, Jürgen Brugger, Demetri Psaltis, Christophe Moser, Nikolaos Nianias, Eirini Kakkava, Georgia Konstantinou, Lorenz Hagelüken, Jieping Wang

Additive manufacturing (AM) methods are being integrated in ceramics fabrication either as the main manufacturing tool or for auxiliary purposes. By using polymers, powders and preceramic formulated materials, AM techniques are pushing towards higher resol ...

2020

A miniaturized selective laser melting device for operando X-ray diffraction studies

Helena Van Swygenhoven, Steven Van Petegem, Samy Hocine, Nicola Casati

We report on the development of a miniaturized device for operando X-ray diffraction during laser 3D printing. The printing chamber has a size of only 130 x 135 x 34 mm(3) and is optimized to be installed at synchrotron beamlines. We describe the design co ...

ELSEVIER2020

Neutron Diffraction and Diffraction Contrast Imaging for Mapping the TRIP Effect under Load Path Change

Helena Van Swygenhoven, Efthymios Polatidis, Markus Strobl

The transformation induced plasticity (TRIP) effect is investigated during a load path change using a cruciform sample. The transformation properties are followed by in-situ neutron diffraction derived from the central area of the cruciform sample. Additio ...

MDPI2020

Deformation mechanisms in a superelastic NiTi alloy: An in-situ high resolution digital image correlation study

Helena Van Swygenhoven, Efthymios Polatidis

An in-situ high resolution digital image correlation investigation during uniaxial tensile deformation reveals the recoverable and the non-recoverable strain mechanisms in a Ni51Ti49 alloy with a mean grain size of 35 mu m. Recoverable strain is due to the ...

2020

Phase Studies of Additively Manufactured Near Beta Titanium Alloy-Ti55511

Helena Van Swygenhoven, Nicola Casati

The effect of electron-beam melting (EBM) and selective laser melting (SLM) processes on the chemical composition, phase composition, density, microstructure, and microhardness of as-built Ti55511 blocks were evaluated and compared. The work also aimed to ...

2020

Measurement and prediction of the transformation strain that controls ductility and toughness in advanced steels

Helena Van Swygenhoven, William Curtin, Francesco Maresca, Efthymios Polatidis

New-generation multi-phase martensitic steels derive their high strength from the body-centered cubic (BCC) phase and high toughness from transformation of the metastable face-centered cubic (FCC) austenite that transforms into martensite upon loading. In ...

PERGAMON-ELSEVIER SCIENCE LTD2020

Operando X-ray diffraction during laser 3D printing

Helena Van Swygenhoven, Steven Van Petegem, Samy Hocine, Nicola Casati

Laser based additive manufacturing allows to build a designed shape layer-by-layer, offering versatility and flexibility to many metallurgical sectors. The fast cooling rates and repeated heat cycles depending on the laser and scanning parameters are not e ...

2020

Influence of thermo-mechanical history on the ordering kinetics in 18 carat Au alloys

Nadine Baluc, Helena Van Swygenhoven, Steven Van Petegem, Marina Garcia Gonzalez

Precious alloys are subjected to a series of mechanical and thermal operations during manufacturing. For 18 carat gold alloys the processing operations can induce L1(0) ordered nanodomains, known to lead to the buildup of residual stresses, which are the p ...

PERGAMON-ELSEVIER SCIENCE LTD2020

The interplay between deformation mechanisms in austenitic 304 steel during uniaxial and equibiaxial loading

Helena Van Swygenhoven, Wei-Neng Hsu, Efthymios Polatidis

The preferred deformation mechanisms with respect to the load path are studied in a medium stacking fault energy 304 austenitic stainless steel that exhibits both transformation induced plasticity and twinning induced plasticity. In situ neutron diffractio ...

2019

In situ tension-tension strain path changes of cold-rolled Mg AZ31B

Helena Van Swygenhoven, Steven Van Petegem

The mechanical behavior of cold-rolled Mg AZ31B is studied during in-plane multiaxial loading and tension-tension strain path changes performed on cruciform samples using in situ neutron diffraction and EBSD. The results are compared with uniaxial tension ...

2019

Following Microstructures during Deformation: In situ X-ray/Neutron Diffraction and HRDIC

Helena Van Swygenhoven, Efthymios Polatidis

The mechanical behavior of three engineering materials is studied employing in situ deformation methods. The study covers metastable austenitic steels with different stacking fault energies during multiaxial loading, a Ti-6Al-4V alloy processed by electron ...

IOP PUBLISHING LTD2019

In situ characterization of work hardening and springback in grade 2 alpha-titanium under tensile load

Helena Van Swygenhoven

Plastic effects during sheet metal forming can lead to undesirable distortions in formed components. Here, the three-stage work hardening and plastic strain recovery ("springback") in a cold-rolled, alpha-phase commercially pure titanium is examined. Inter ...

2019

In situ characterization of a high work hardening Ti-6Al-4V prepared by electron beam melting

Helena Van Swygenhoven, Karl Alan Sofinowski, Nicola Casati

A multi-phase Ti-6Al-4V prepared by electron beam melting and thermal post treatments has been shown to exhibit increased strength and ductility over standard wrought or hot isostatic pressed Ti-6-Al-4V. The mechanical improvements are due to a prolonged, ...

2019

Laue microdiffraction characterisation of as-cast and tensile deformed Al microwires

Andreas Mortensen, Helena Van Swygenhoven, Léa Deillon, Steven Van Petegem, Suzanne Godelieve Alphonsine Verheyden

Single-crystalline cast aluminium microwires with a diameter near 15 are characterised by Laue microdiffraction. A microwire in the as-cast condition exhibits a misorientation below over a length of 500 . The measured density of geometrically necessary dis ...

TAYLOR & FRANCIS LTD2019

Enhanced precipitate growth at reduced temperatures during chemical ordering in deformed red gold alloys

Nadine Baluc, Helena Van Swygenhoven, Steven Van Petegem, Marina Garcia Gonzalez, Samy Hocine

Manufacturing of red gold components relies widely on controlling the formation of ordered precipitates during thermo-mechanical processing. The ordered phase hardens the material, makes it less workable and introduces residual stresses. We show that an in ...

PERGAMON-ELSEVIER SCIENCE LTD2019