Structural features of uranyl acrylate complexes with s-, p-, and d-monovalent metals

A series of uranyl acrylate complexes with s-, p-, and d- monovalent cations (Li, Na, Tl, and Ag) was synthesized and characterized by single crystal X-ray diffraction and IR spectroscopy. We demonstrated that the nature of the monovalent cation strongly affects the composition and crystal structure of an uranyl acrylate. Li[UO2(acr)3]·H2O (1, acr=CH2CHCOO−) crystallizes in the tetragonal crystal system and is built of chains which are connected through hydrogen bonding. The presence of an acrylic acid dimer in the reaction results in the monoclinic compound Na3[UO2(acr)3][UO2(acr)2.5(CH2CHCOOCH2CH2COO)0.5]2·5H2O (2), in which the acrylic dimer shares a position with both the acrylate anion and a water molecule. Tl[UO2(acr)3] (3) exists as two polymorphs and crystallizes in either P1̅ (3a) or P213 (3b) space groups. The polymorphs differ in the dimensionality, 2D for 3a and 3D for 3b, and density. Ag2[UO2(NO3)2(acr)2]·2Hacr (4) is the first example of the Ag atom coordination to the acrylate anion through the vinyl group. In 4, the Ag–C bonds enhances the connectivity of the trinuclear [Ag2UO2(acr)2(Hacr)2(NO3)2] clusters into a layered coordination polymer. A detailed structural study of the obtained compounds was performed using Voronoi-Dirichlet tessellation.

Using of the Averaged Voronoi Polyhedron for the Equiaxed Solidification Modeling

For the characterization of the equiaxed polycrystalline structure the Dirichlet tessellation is often used. The results of this space decomposition Voronoi polyhedrons are convex but not necessarily bounded. Size, volume and other characteristics of these bodies are the random variables. Parameters of theAveraged Voronoi Polyhedronare used in the presented paper for the modeling of the diffusion controlled peritectic transformation. Proposed model takes into account decreasing of the transformation interface surface in the remote regions of the diffusion field due to the probabilistic grains impingements. The results of the modeling are compared with the microstructure of the Pb-32 wt.% Bi alloy and thermal analysis results.

Analysis of the Homogeneity of Particle Refinement in Friction Stir Processing Al-Si Alloys

Friction Stir Processing (FSP) has potential for locally enhancing the properties of Al-Si alloy castings, for demanding applications within the automotive industry, by greatly refining the second phase particle size. In the present study, the homogeneity of particle refinement and second phase spatial distribution within the process zone, as well as the relationship to the processing parameters, were investigated in a gravity die cast Al-Si LM24/A380 alloy, subjected to a range of FSP conditions. Detailed image analysis and the dirichlet tessellation method were used to quantify particle clustering. ‘Stop-action’ experiments were also used to study the process of particle break up, by following the behaviour through the deformation zone surrounding the tool.