László Sturz

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G. Zimmermann

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Nathalie Mangelinck‐Noël

Institut des Matériaux, de Microélectronique et des Nanosciences de Provence

V.T. Witusiewicz

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U. Hecht

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Shaun McFadden

University of Ulster

Charles‐André Gandin

Centre de Mise en Forme des Matériaux

David J. Browne

Queen's University Belfast

Henri Nguyen-Thi

Université de Toulon

B. Billia

Aix-Marseille Université

Steffen Rex

KU Leuven

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Centre National de la Recherche Scientifique

RWTH Aachen University

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Institut des Matériaux, de Microélectronique et des Nanosciences de Provence

Aix-Marseille Université

Aging Community Coordinated Enterprises and Supportive Services (United States)

Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR)

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Arab Community Center for Economic and Social Services

FH Aachen

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Investigation of the initial transient in directional solidification of binary AlCu alloys

Materials Science and Engineering A (2005)

A. Drevermann László Sturz Nils Warnken G. Zimmermann

Directional solidification

Temperature Gradient

Transient (computer programming)

10.1016/j.msea.2005.08.164

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Citations (4)

Thermodynamic description and unidirectional solidification of eutectic organic alloys: II. (CH3)2C(CH2OH)2–(NH2)(CH3)C(CH2OH)2 system

Acta Materialia (2004)

V.T. Witusiewicz László Sturz U. Hecht Steffen Rex

CALPHAD

Eutectic bonding

10.1016/j.actamat.2004.07.013

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Citations (27)

Analysis of a Microgravity Solidification Experiment for Columnar to Equiaxed Transitions with Modeling Results

Materials science forum (2010)

Shaun McFadden David J. Browne László Sturz G. Zimmermann

This paper studies the Columnar to Equiaxed Transition (CET) in an Al-7wt%Si binary alloy with and without Al-Ti-B grain refiner. A microgravity experiment was designed to produce a CET in this alloy system. The experiment was flown onboard the MAXUS-7 sounding rocket platform, which achieved twelve minutes of microgravity. Examples of CET were successfully produced during the unmanned flight. Temperature data were recorded from thermocouples in the crucible walls of the furnace. Post-mortem material characterization of the grain structure was also performed. Subsequently a model of the furnace, which used a front-tracking model of solidification and an inverse heat calculation method, was developed. In this paper, results from the model are compared to the experimental findings; agreement is found with the CET predictions. The results from the model are then used to compare findings with the CET criterion of Hunt from the literature. Agreement is found between the model predictions and the Hunt criterion.

Equiaxed crystals

Crucible (geodemography)

Thermocouple

Rocket (weapon)

Sounding rocket

10.4028/www.scientific.net/msf.649.361

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Citations (9)

Investigations on Columnar-to-Equiaxed Transition in Binary Al Alloys with and without Grain Refiners

Materials science forum (2006)

László Sturz G. Zimmermann

We have investigated the columnar to equiaxed transition experimentally in directionally solidified hypoeutectic binary AlSi alloys with and without grain refinement particles and for different processing parameters in the framework of the ESA-MAP CETSOL (Columnar-to-equiaxed transition in solidification processing). A power-down technique was used in a Bridgman-Stockbarger type gradient-furnace to simultaneously increase the solidification rate and decrease the temperature gradient in the cylindrical sample during directional solidification vertically upwards. The position of the CET was determined from the cut and polished samples and correlated to the applied cooling rate for different experiments. Critical parameters for the temperature gradient and the solidification rate at the transition were determined from cooling curves measured within the sample and from a time-of-flight analysis of ultrasonic pulses propagated in the solid part of the sample and being reflected at the solid-liquid interface. The critical values found are compared to the deterministic models of Hunt and of Martorano et al. The objective of this contribution is the presentation of preliminary results for the different alloys and processing parameters of ground-based experiments. These results will be used for the testing of different models describing the CET within the framework of the ESA-MAP CETSOL and for the preparation of comparative microgravity experiments.

Equiaxed crystals

Directional solidification

Temperature Gradient

10.4028/www.scientific.net/msf.508.419

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Citations (8)

Time-dependent directional solidification of binary Al–Cu alloys in the initial transient

International Journal of Materials Research (formerly Zeitschrift fuer Metallkunde) (2007)

G. Zimmermann A. Drevermann László Sturz Nils Warnken

Abstract At the start of directional solidification a complex interaction between the movement of the solidification front, the concentration pile-up ahead of the front and the temperature gradient at the solid – liquid interface takes place. Experiments with binary Al-Cu1.3 wt.% were performed in this regime in a Bridgman – Stockbarger type gradient furnace allowing solidification with a planar solid – liquid interface. The time-dependent velocity and temperature profiles were measured during the experiments, whereas the concentration profiles were analysed from the processed samples. The experimental results were compared to predictions from numerical simulations based on the model of Coriell et al. Good agreement is obtained in the description of time-dependent diffusive, planar growth in the initial transient.

Directional solidification

Temperature Gradient

Transient (computer programming)

Binary alloy

10.3139/146.101454

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Citations (2)

In-situ and real-time investigation of the columnar-equiaxed transition in the transparent alloy system neopentylglycol-camphor onboard the sounding rocket TEXUS-47

Journal of Physics Conference Series (2011)

László Sturz G. Zimmermann

The low-gravity experiment TRACE (TRansparent Alloys in Columnar Equiaxed solidification) has been performed onboard the sounding rocket TEXUS-47 to enable the investigation of dendritic growth and the dendrites' columnar to equiaxed transition during solidification. Low-gravity conditions provide solidification under diffusive heat and mass transfer conditions and without sedimentation or buoyancy of equiaxed dendrites or nucleation seeds to simplify the boundary conditions for dendritic microstructure simulation. In addition the transparent organic alloy system Neopentylglycol (NPG) - (D)Camphor (DC) was used to allow for a real-time and in-situ observation of the microstructure evolution with standard optics. For the flight experiment all relevant experimental parameters like thermal gradient, solidification velocity and undercooling within the bulk liquid and at the columnar dendritic tips have been determined by image analysis or from thermocouple recordings within the solidifying alloy. This allows a very detailed comparison with results of existing models for dendritic growth and for columnar-to-equiaxed transition. Here we present a summary of the experimental findings in comparison with results of some of the theoretical models.

Equiaxed crystals

Supercooling

Thermocouple

Sounding rocket

Directional solidification

10.1088/1742-6596/327/1/012002

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Citations (9)

Investigation of columnar-to-equiaxed transition in solidification processing of AlSi alloys in microgravity – The CETSOL project

Journal of Physics Conference Series (2011)

Gottfried Zimmermann László Sturz B. Billia Nathalie Mangelinck‐Noël H. Nguyen Thi

Grain structures observed in most casting processes of metallic alloys are the result of a competition between the growth of several arrays of dendrites that develop under constrained and unconstrained conditions. Often this leads to a transition from columnar to equiaxed grain growth during solidification (CET). A microgravity environment results in suppression of buoyancy-driven melt flow and so enables growth of equiaxed grains free of sedimentation and buoyancy effects. This contribution presents first results obtained in experiments on-board the International Space Station (ISS), which were performed in the frame of the ESA-MAP programme CETSOL. Hypoeutectic aluminium-silicon alloys with and without grain refiners were processed successfully in a low gradient furnace (MSL-LGF). First analysis shows that in the non grain refined samples columnar dendritic growth exists, whereas CET is observed in the grain refined samples. From analysis of the thermal data and the grain structure the critical parameters for the temperature gradient and the cooling rate describing CET are determined. These data are used for initial numerical simulations to predict the position of the columnar-to-equiaxed transition and will form a unique database for calibration and further development of numerical CET-modeling.

Equiaxed crystals

Temperature Gradient

Crucible (geodemography)

10.1088/1742-6596/327/1/012003

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Citations (24)

Effect of convection on directional solidification in transparent succinonitrile–2.2wt.%(d)camphor alloy

Acta Materialia (2021)

V.T. Witusiewicz László Sturz Alexandre Viardin C. Pickmann G. Zimmermann

Succinonitrile

Directional solidification

Camphor