Surface-Directed Spinodal Decomposition on a Macroscopic Scale in a Nitrogen and Carbon Alloyed Steel

Abstract

Interactions with the macroscopic specimen surface can profoundly modify phase-separation processes. This has previously been observed in liquids and polymer films and is theoretically described by the theory of surface-directed spinodal decomposition (SDSD). Here we report first observations of SDSD in a metallic alloy on a macroscopic scale. The influence of the surface leads to the development of concentric domains extending over the whole 10 mm thick cylindrical steel specimen, due to long-range interactions via elastic stresses and long-range diffusion of the interstitial elements nitrogen and carbon.

Electrochromic properties of self-organized multifunctional V2O5–polymer hybrid films

“…These structural characteristics contribute to their outstanding mechanical properties, combining both high stiffness and toughness. [3][4][5][6] Very recently, we developed a biomimetic fabrication concept for the synthesis of organic-inorganic composites based on liquid crystal (LC) formation of organic and inorganic components. 7 The LC 'gluing' polymer used was a statistical polyoxazoline with pendant cholesteryl and carboxyl side chains, enabling the polymer, on the one hand, to form chiral-nematic lyotropic phases on the length scale of several hundreds of micrometers upon shearing, and on the other hand, to selectively bind to nanoparticle faces via electrostatic interactions or hydrogen bridges.…”

Self-assembled hierarchically structured organic–inorganic composite systems

“…This oriented arrangement of aligned inorganic nanoplatelets within the organic matrix is called mesocrystal, which is a (3D) superstructure of nanocrystal building units with common crystallographic orientation [9][10][11]. The organic collagen matrix itself is hierarchically structured on several levels since the collagen fibrils are joined together to fiber bundles that finally form a lamellar structure [6,12]. Proteoglycans may function as gluing components sticking the structural constituents together [8].…”

“…The high fraction of inorganic crystals is the load-bearing element providing stiffness to the material while the organic phase surrounding the inorganic particles plays a decisive role for the toughness of the material [7,8]. Two structural characteristics contribute essentially to the exceptional mechanical performance of biominerals: a sophisticated hierarchical structure of organic and inorganic components and a well-controlled coupling at the interface of both constituents [5,6].…”

“…On the lower hierarchical level, ranging from the nanometer length scale up to the scale of tens of micrometers, bone consists of highly ordered, staggered arrays of hydroxyapatite mineral platelets with a thickness of 2-4 nm embedded in collagen fibers (scheme 1) [6,12]. This oriented arrangement of aligned inorganic nanoplatelets within the organic matrix is called mesocrystal, which is a (3D) superstructure of nanocrystal building units with common crystallographic orientation [9][10][11].…”

“…Prominent examples include nacre and bone [3,4]. These biomaterials are well-known for their outstanding mechanical performance combining both high stiffness and toughness [5,6]. Biominerals exhibit a fracture resistance which by far exceeds the one of the respective pure inorganic component.…”