Microstructure evolution in containerless solidification

Date

Dec 11, 2017

Time

1:00 PM - 2:00 PM

Speaker

Dr. Jonas Valloton

Affiliation

University of Alberta, Edmonton, Canada

Language

en

Main Topic

Materialien

Other Topics

Materialien, Physik

Host

Brit Präßler-Wüstling

Description

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

Last modified: Dec 11, 2017, 8:49:45 AM