Microstructure evolution in containerless solidification

Datum

11.12.2017

Zeit

13:00 - 14:00

Sprecher

Dr. Jonas Valloton

Zugehörigkeit

University of Alberta, Edmonton, Canada

Sprache

en

Hauptthema

Materialien

Andere Themen

Materialien, Physik

Host

Brit Präßler-Wüstling

Beschreibung

For decades, the most widely used experimental technique to generate benchmark data for numerical simulations has been the Bridgman type of directional solidification. However, Bridgman type solidification experiments cannot achieve solidification rates high enough to compare with the solidification structures resulting from casting processes such as strip casting, rheo-casting and spray forming where high cooling rates and high undercoolings induce vast deviation from equilibrium during solidification. To overcome these limitations containerless solidification techniques have recently established themselves as the solidification techniques of choice. In this work, containerless rapid solidification of Al-alloys and D2 steel is investigated experimentally using the Impulse Atomization (IA) and ElectroMagnetic Levitation (EML) techniques. Powders of size ranging from 100 to 1400 μm corresponding to a wide range of cooling rates (~102-105 K/s) and undercoolings have been generated by IA and droplets of ~6-7 mm in diameter have been rapidly solidified by EML. The effect of undercooling and cooling rate on the on the solidification path and the final microstructure are investigated through Cells Spacing measurements, Micro-hardness tests as well as X-rays Diffraction (XRD), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), Electron Backscatter Diffraction (EBSD). In addition, the more advanced characterization tools such as Neutron Diffraction and X-Ray Micro-Tomography are performed. IA and EML techniques are found to be complementary in fully characterizing rapid solidification microstructures.

Links

• Seminars at the IFW

Letztmalig verändert: 11.12.2017, 08:49:45