XRISE-M: X-radiography facility for solidification and diffusion studies of alloys aboard sounding rockets

Abstract

A compact fully-protected micro-focus X-radiography facility (XRISE-M) is presented for the study of microstructure evolution during solidification of thin liquid alloy samples and chemical diffusion in liquid binary alloys in-situ and in real-time aboard a sounding rocket. XRISE-M presently enables the simultaneous processing of either two near-isothermal solidification furnaces or a combination of a linear-shear cell diffusion furnace and a near-isothermal solidification furnace. For optimal detector calibration shortly before flight the furnaces can be rotated around the central beam axis and calibration images can be recorded. The facility allows for a pre-heating of the samples into the liquid state prior to lift-off without leakage during the ascent phase at accelerations of up to 27 g. Macro-segregation on re-melting of thin metal samples for microstructure evolution investigations is prevented by an inclinable furnace metric. The use of ion-getter pumps for vacuum generation enables to exploit the entire available time of reduced gravity for image recording and data acquisition. With the device and currently available sample environments microstructure formation upon solidification and chemical diffusion under purely diffusive conditions in alloys can be investigated. The facility can be used equally for other investigations such as granular matter dynamics or metal foaming provided suitable experiment inserts are developed in the future.

Surface boundary-dendrite interactions in thin metallic Al-alloy samples

“…1(a) and (b) for the Al-Cu and the Al-Ge alloy, respectively. While the Al 15 wt.%Cu sample was processed in microgravity condition on the sounding rocket flight MAPHEUS-7 in the module X-RISE-M [34], the Al-29 wt.%Ge alloy was processed horizontally on ground in the facility X-RISE-G [35]. In order to investigate the orientation of the dendrites in three dimensions, X-ray computed tomography was performed on the solid samples post-mortem with a Phoenix Nanotom 160NF.…”

“…It can therefore not be conclusively clarified whether nucleation of Al-grains at the sample boundary favors a special orientation. A more accurate statement could be made with a higher number of grains sampled, but this is difficult because opportunities for experiments in microgravity are rare [34,38]. What can be stated, however, is that the crystallographic {100} plane of most grains nucleated in microgravity is not parallel to the sample plane in the solidified samples, as one might assume by looking only at the projected dendrite morphologies, which in many cases show a four-fold symmetry (see Fig.…”

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

“…Additional near-isothermal solidification experiments have been carried out on two sounding rocket missions MAPHEUS-6 and 7 in the years 2016 and 2018, respectively, also using X-ray observation technology and a different isothermal furnace design 23 . Two Al-15 wt.% Cu samples in two individual solidification furnaces sharing one X-ray source have been solidified in microgravity during MAPHEUS-7, and one Al-46wt.% Ge sample during MAPHEUS-6 24 . Nucleation dynamics as well as dendrite and melt concentration evolution were monitored in-situ.…”

“…However, X-ray radioscopy is essential to monitor the diffusion process and rule out disturbing effects. For selected binary alloys sounding rocket (MAPHEUS) experiments using the XRISE-M facility 24 were compared with ground-based experiments 54 , 55 . It was shown that diffusion experiments can be successfully carried out on ground, if a stable density-layering of the liquids is established in the sample.…”

Isothermal furnace for long-term in situ and real-time X-radiography solidification experiments

“…Spatial and temporal resolution for X-ray radiography improved later, when experiments were performed at high brilliant synchrotron sources 1 or using advanced X-ray tube and detector technologies 6 .Laboratory-based X-ray sources have become a powerful tool in the last years with obvious flexibility benefits over synchrotron sources [7][8][9] . Advances in image technology, detector development and high-resolution X-ray sources combined with a wide range of furnace setups enabled the investigation of microstructure during solidification in institute laboratories and on microgravity platforms; sounding rockets or parabolic flights, for example [10][11][12][13] . Columnar and equiaxed dendritic growth 9,[14][15][16][17] , grain coarsening 18,19 and grain fragmentation 20,21 effects have been studied using thin samples with in-situ X-ray techniques under both terrestrial and microgravity conditions.…”