DECLIC is a multi-user facility to investigate critical fluids behaviour and directional solidification of transparent alloys, developed in the frame of a joint NASA/CNES research program. The instrument is a miniaturized thermo optical laboratory in which one can plug inserts containing the materials to be studied.
Research Containing: Microstructure
Dynamical microstructure formation in 3D directional solidification of transparent model alloys: in situ characterization in DECLIC Directional Solidification Insert under diffusion transport in microgravity
To clarify and characterize the fundamental physical mechanisms active in the dynamical formation of three-dimensional (3D) arrays of cells and dendrites under diffusive growth conditions, in situ monitoring of series of experiments on transparent model alloy succinonitrile – 0.24 wt% camphor was carried out under low gravity in the DECLIC Directional Solidification Insert on-board the International Space Station. These experiments offered the very unique opportunity to in situ observe and characterize the whole development of the microstructure in extended 3D patterns. The experimental methods will be first briefly described, including in particular the observation modes and the image analysis procedures developed to quantitatively characterize the patterns. Microgravity environment provided the conditions to get quantitative benchmark data: homogeneous patterns corresponding to homogeneous values of control parameters along the whole interface were obtained. The sequence of microstructure formation will be presented as well as the evolution of the primary spacing which is one of the most important pattern characteristic. Time evolution of this primary spacing during the microstructure development will be analysed to identify the mechanisms of spacing selection and adjustment; the importance of the macroscopic interfacial curvature will be pointed out.
The structure formation of the liquid-phase products of the synthesis of the model SHS mixture of the thermite type NiO + Ni + Al under microgravity conditions aboard the International Space Station ALPHA is investigated. Comparative investigations of the microstructure and chemical and phase compositions of synthesis products formed on the Earth and under microgravity conditions are performed. In the process of terrestrial experiments, the main attention was paid to the search for optimal compositions capable of burning under reduced pressure with a minimal spread of combustion products.
The Shear History Extensional Rheology Experiment (SHERE) is an International Space Station (ISS) glovebox experiment designed to study the effect of preshear on the transient evolution of the microstructure and viscoelastic tensile stresses for monodisperse dilute polymer solution. The SHERE experiment hardware was launched on Shuttle Mission STS-120 (ISS Flight 10A) on October 22, 2007, and 20 fluid samples were launched on Shuttle Mission STS-123 (ISS Flight 1J/A) on March 11, 2008. Astronaut Gregory Chamitoff performed experiments during Increment 17 on the ISS between June and September 2008. A summary of the ten year history of the hardware development, the experiment’s science objectives, and Increment 17’s flight operations are discussed in the paper. A brief summary of the preliminary science results is also discussed.