Thomas Weißgärber

Formation and interface structure of TiC particles in dispersion-strengthened Cu alloys

Abstract TiC-dispersion-strengthened Cu alloys were prepared by mechanical alloying and subsequent hot extrusion. The evolution of the microstructure with respect to the preparation process is analysed by transmission electron microscopy techniques. The TiC dispersoids are formed in situ by the reaction of Ti and graphite. Ti diffuses from the pre-alloyed CuTi matrix to C inclusions which are embedded in the matrix after high-energy milling. Heat treatment of the powder mixtures at 400°C leads to heterogeneous nucleation of TiC at the C/Cu interface. Thereby a well defined cube-on-cube orientation relationship is established between TiC and the Cu matrix. A study of the morphology of the TiC dispersoids shows that they are faceted on {111}TiC {110}TiC and {100}TiC planes and possess ledges on the atomic scale. The TiC/Cu interfaces are atomically abrupt and free of interface phases. The {100}TiC∥{100}Cu and ⟨110⟩TiC∥⟨110⟩Cu topotaxy leads to a misfit of 17.6% between the adjacent lattices. This misfit is ...

Rapidly solidified Fe-base alloys as electrode materials for water electrolysis

Abstract Amorphous ribbons of the systems Fe60Co20Si10B10 and Fe50Co20V10Si10B10 have been prepared via melt spinning to be used as electrode materials in alkaline water electrolysis. It turned out that the gas atmosphere during melt-spinning has a significant impact on the surface morphology and microstructure of the ribbons. Furthermore, a comprehensive characterization of the microstructure depending on the peripheral speeds of the cooling wheel was conducted. Moreover, the transition from the amorphous to the crystalline state was investigated via differential scanning calorimetry measurements. Preliminary electrochemical investigations suggest a noticeable improvement of the electrocatalytic activity of the melt-spun amorphous ribbons after an anodic–cathodic pretreatment.