X-radiography front tracking gradient furnace for directional solidification of bulk Al-alloys.

A unique gradient furnace for directional solidification experiments with bulk Al-alloy samples developed at German Aerospace Center is presented. It allows for in situ process control in solidifying samples by using x-radiography, and further insight into the solidification process is gained in combination with x-ray computational tomography on the solidified samples. Tracking of interfaces during directional solidification of bulk samples via in situ x-radiography (TIREX) enables the investigation of the melting process and observation of the movement of the entire mushy zone through the sample, tracing the solid-liquid interface during directional solidification and correlating the observations with the microstructure of the samples.

In-situ X-ray monitoring of solidification and related processes of metal alloys.

X-ray radioscopy enables the in-situ monitoring of metal alloy processes and then gives access to crucial information on the dynamics of the underlying phenomena. In the last decade, the utilisation of this powerful imaging technique has been adapted to microgravity platforms such as sounding rockets and parabolic flights. The combination of microgravity experimentation with X-ray radioscopy has resulted in a leap in the understanding of fundamental science and has opened new paths in the fields of materials science.

Chemical short-range order in liquid Ni-Cu.

Neutron diffraction in combination with isotopic substitution on the zero-scattererNiCushows indications for chemical short-range order in the stable liquid as evidenced by oscillations in the concentration-concentration structure factor(). This points towards a non-ideal solution behavior of Ni-Cu contrary to common believe but in agreement with measurements of free enthalpy of mixing. The temperature dependence ofat small momentum transfer provides evidence of critical compositional fluctuations in NiCumelts.

synchrotron XRD measurements during solidification of a melt in the CaO-SiOsystem using an aerodynamic levitation system.

Phase formation and evolution was investigated in the CaO-SiOsystem in the range of 70-80 mol% CaO. The samples were container-less processed in an aerodynamic levitation system and crystallization was followedby synchrotron x-ray diffraction at the beamline P21.1 at the German electron synchrotron (DESY).