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Michel Rappaz

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Related publications (85)

Modeling Nucleation and Growth of Zinc Grains in Hot-Dip Galvanized Coatings

Hot-dip galvanized Zn-0.2wt%Al coatings on steel sheets exhibit a strong basal texture ({0001} parallel to the sheet plane). Part of this texture call be explained by the faster growth of < 10 (1) over bar0 > dendrites as compared with < 0001 >, granting b ...

Minerals, Metals & Materials Soc, 184 Thorn Hill Rd, Warrendale, Pa 15086-7514 Usa2009

A mesoscale granular model for the mechanical behavior of alloys during solidification

Michel Rappaz, Stéphane Vernède, Jonathan Dantzig

We present a two-dimensional granular model for the mechanical behavior of an ensemble of globular grains during solidification. The grain structure is produced by a Voronoi tessellation based on an array of predefined nuclei. We consider the fluid flow ca ...

Elsevier2009

A 3D Granular Model Of Equiaxed-Granular Solidification

Jean-Luc Desbiolles, Michel Rappaz, André Phillion

The solidification of an aluminum-copper alloy has been simulated in 3D using a granular model. Compared to previous similar 2D approaches for where only one phase is continuous, the extension to 3D allows for concurrent continuity of the solid and liquid ...

Minerals, Metals & Materials Soc, 184 Thorn Hill Rd, Warrendale, Pa 15086-7514 Usa2009

Prediction of solidification behaviour via microstructure models based on granular structures

Michel Rappaz, Stéphane Vernède, André Phillion

Two important factors affecting hot tearing - semi-solid constitutive behaviour and grain percolation - have been simulated through the use of microstructure models based on granular structures. The semi-solid model geometry is based on a modified Voronoi ...

Maney Publishing2009

Study of twinned dendrite growth stability

Michel Rappaz, Jonas Valloton, Mario Alberto Salgado Ordorica

Under certain thermal conditions (G approximate to 1 x 10(4) K/m, v(s) approximate to 1 x 10(-3) m/s), < 1 1 0 > twinned dendrites appear in aluminum alloys and can overgrow regular columnar dendrites, provided that some convection is also present in the m ...

Elsevier2009

Peritectic solidification of Cu-Sn alloys: Microstructural competition at low speed

Michel Rappaz, Jean-Daniel Wagnière, Lucien Germond

Directional solidification experiments on Cu-Sn peritectic alloys have been conducted at very low velocity in a high-thermal-gradient Bridgman furnace. The size of the samples has been reduced in order to decrease natural convection and the associated macr ...

Elsevier2009

Solidification microstructures and solid-state parallels: Recent developments, future directions

Wilfried Kurz, Michel Rappaz

Rapid advances in atomistic and phase-field modeling techniques as well as new experiments have led to major progress in solidification science during the first years of this century. Here we review the most important findings in this technologically impor ...

Elsevier2009

PHASE FIELD MODELING OF EQUILIBRIUM SHAPES AND GROWTH MORPHOLOGIES IN Al-Zn ALLOYS

Michel Rappaz, Jonathan Friedli, Aurèle Mariaux

The anisotropy of the solid-liquid interfacial energy, gamma(sl), plays a key role in the accurate prediction of growth morphologies in metallic alloys. This interfacial energy anisotropy can vary duo to alloy composition, especially when that of the pure ...

Minerals, Metals & Materials Soc, 184 Thorn Hill Rd, Warrendale, Pa 15086-7514 Usa2009

EBSD: a powerful microstructure analysis technique in the field of solidification

Alain Jacot, Michel Rappaz, Christoph Niederberger, Emmanuelle Boehm Courjault, Aurèle Mariaux, Mario Alberto Salgado Ordorica

This paper presents a few examples of the application of electron back-scatter diffraction (EBSD) to solidification problems. For directionally solidified Al-Zn samples, this technique could reveal the change in dendrite growth directions from < 100 > to < ...

2009

Nd:YAG laser joining between stainless steel and nickel-titanium shape memory alloys

Aïcha Hessler-Wyser, Michel Rappaz, Jonas Vannod

Nickel-Titanium (NiTi) shape memory alloys are often used in medical component devices, for instance as guide wires for neurological surgery applications. The manufacture of such devices becomes more and more challenging, especially considering the need to ...

2008

Orientation selection in dendritic evolution

Michel Rappaz

Computational and experimental demonstration of dendritic crystal growth direction and the morphologic diversity of the resulting dendritic structures are discussed. The primary dendrite growth directions can vary continuously between different crystallogr ...

2008

A new tensile test for aluminum alloys in the mushy state: Experimental method and numerical modeling

Michel Rappaz, Vincent Mathier, Piero Daniele Grasso

A fairly simple experimental setup has been designed for testing the resistance of the mushy zone of alloys during solidification under tensile conditions. It has been used to study the effect of coalescence among the solid grains at a late stage of solidi ...

2008

Twinned dendrite growth in binary aluminum alloys

Michel Rappaz, Mario Alberto Salgado Ordorica

The formation of twinned dendrites (feathery grains) in binary Al-Zn, Al-Mg, Al-Cu and Al-Ni alloys has been studied in specimens directionally solidified under identical thermal conditions, i.e. G approximate to 100 K cm(-1), v approximate to 1 mm s(-1), ...

Elsevier2008

Growth directions in directionally solidified Al-Zn and Zn-Al alloys near eutectic composition

Michel Rappaz, Martin Rhême

Growth directions and crystallographic orientations of solidification microstructures have been measured in Al-Zn alloy near the eutectic composition. Al dendrites in Al-92 wt.% Zn alloy were found to grow along the I 10) directions while Zn dendrites in A ...

Elsevier2008

Grain selection and texture evolution in directionally solidified Al-Zn alloys

Michel Rappaz

In a recent contribution, we have reported that dendrites in the aluminum-zinc binary system can change their growth direction continuously from {100} to {110} as the concentration of zinc CZn increases from 5 to 90 wt pct.[1] This was interpreted as an in ...

Springer US2008

Application of single pan thermal analysis to Cu-Sn peritectic alloys

Michel Rappaz, Thomas Campanella, Shigeo Nakanishi

Single pan thermal analyses (SPTA) have been performed on Cu–14.5 wt.% Sn, Cu–21.3 wt.% Sn and Cu–26.8 wt.% Sn peritectic alloys. For this purpose, a SPTA assembly has been built and calibrated. As the latent heat is a function of temperature and compositi ...

Elsevier2008

The influence of 0-0.1 wt.% Ni on the microstructure and fluidity length of Sn-0.7Cu-xNi

Michel Rappaz, Tina Ventura

Alloys based on the Sn-0.7Cu-xNi system are potential Pb-free solders. In this paper we report on the solidification characteristics and microstructures of Sn-0.7Cu alloys containing 0-1,000 ppm nickel. The microstructural observations show that increasing ...

Springer Verlag2008

Application of single pan thermal analysis to Cu-Sn peritectic alloys

Michel Rappaz, Thomas Campanella

Single pan thermal analyses (SPTA) have been performed on Cu-14.5 wt.% Sn, Cu-21.3 wt.% Sri and Cu-26.8 wt.% Sit peritectic alloys. For this purpose, a SPTA assembly has been built and calibrated. As the latent heat is a function of temperature and composi ...

Elsevier2008

Two-phase modelling of hot tearing in aluminium alloys using a semi-coupled approach

Jean-Marie Drezet, Michel Rappaz, Vincent Mathier

Hot tearing, one of the most severe defects observed in castings, is due to both tensile stresses and lack of interdendritic liquid feeding in the mushy zone. In order to predict this phenomenon, the two-phase averaged conservation equations for mass and m ...

2007

Modeling of porosity formation in multicomponent alloys in the presence of several dissolved gases and volatile solute elements

Michel Rappaz, Gaël Couturier

2006

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