During vertical Bridgman growth of an alloy crystal, local accumulation of solute at the interface center due to buoyancy often causes formation of a deep depression or pit and accelerates morphological instability. Through visualization of the freezing interface during directional solidification of succinonitrile containing ethanol on a rotating table, it was shown that rotation about the ampo...

We calculate numerically the full Floquet-Bloch stability spectrum of cellular array structures in a symmetric model of directional solidification. Our results demonstrate that crystalline anisotropy critically influences the stability of these structures. Without anisotropy, the stability balloon of cells in the plane of wave number and velocity closes near the onset of morphological instabili...

The effects of internal stress and bias field on transformation strain in the Heusler alloy Ni52Mn24.4Ga23.6 were investigated. It was found that both residual internal stress caused by the directional solidification during the growth and additional bias field with a direction consistent with the intrinsic preferential orientation would provide favourable conditions for exhibiting large transfo...

11 IMR KINKEN Research Highlights 2010 Energy-related Materials To manipulate crystal defects and impurities in Si multicrystals is a promising route to improve conversion efficiency of solar cells. Therefore, development of a novel crystal growth technique to permit artificial control of defects has been pursued. It would be ideal if such a technique is based on the practical directional solid...

During directional solidification of alloys, a cellular structure can be observed above a critical pulling speed. Under certain conditions, the cusps behind the cells can present a secondary instability characterized by a periodic emission of liquid droplets. These droplets are transported by the solid, but also migrate towards the solid-liquid interface by temperature gradient zone migration. ...

Nickel-based single crystal superalloy is the most important material for blade preparation. However, some solidification defects inevitably occur during process of preparing single-crystal blades through directional solidification. In this study, in order to study origin misorientation solidification, a model with rejoined platforms was designed according geometry guide vanes. Electron Back-Sc...

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 Internat...

Wire arc additive manufacturing achieves high efficiency and low costs by using a melting wire for directional depositions. Thermal analyses the finite element method have been applied to predict residual stress deformation of fabricated parts. For Ni-based alloy production, predicting solidification microstructure evolution with segregation is needed in order design precise heat treatment proc...

Stray grains are the most severe of solidification defects that occur in industrial single-crystal blade preparation process. In this study, a dummy cluster with different crystal orientations controlled by seeding method was prepared, and influence position circular platform (relative to sample furnace body) on stray grain nucleation investigated. Results show microstructure platforms could be...

The directional solidification of an Elektron 21 magnesium alloy is investigated by in situ synchrotron radiation tomography. To visualize the process, samples are first heated to 800 °C, and melt held at this temperature for 5 min, ensure homogeneity. Subsequently, cooled with a cooling rate 10 K min−1, while every 35 s, one full tomogram acquired. evolution microstructure can be followed 3D o...