Papers by Keyword: Short Range Order (SRO)

Abstract: The effect of chemical composition on the bonding environment of Cu, in a series of Ti1-x Cux and TiN/Cu films, is studied using X-Ray Absorption Spectroscopies (XAFS) at the Cu-K-edge. The EXAFS analysis reveals that in all studied samples Cu is amorphous. However, its bonding environment depends on the chemical composition. More specifically, in the Ti1-xCux films, Cu is coordinated with Ti and Cu and belongs both to intermetallic TiCu and to an amorphous Cu matrix. The coordination number of Cu, i.e., the sum of Ti and Cu first neighbours, increases systematically from 6.3 ± 0.7 to 10.6 ± 0.9 when the Cu content increases from 24.1 to 52.7 at%. On the contrary, in the TiN/Cu films, the type of atoms that consists the 1st nearest neighbour shell of Cu varies as a function of the Cu concentration. More specifically, in the TiN/Cu film with the lowest Cu content (27.3 at%), intermetallic TiCu is detected. At intermediate Cu concentration (37.8 at%), Cu is bonded to both Ti and Cu atoms. Finally, in the TiN/Cu film with the highest Cu content (67.7 at%), Cu is metallic.

Abstract: An increase of the Ge–O coordination numbers (NGeO) from 4 to 5 with decreasing GeO2 content is obtained by diffraction on K2O-GeO2-P2O5 glasses of GeO2 fractions ≥ 50 mole%. First sharp diffraction peaks (FSDP) appear at small scattering vectors Q of 7.5 nm-1. A structural model is already reported which explains this behaviour for that sample (25K2O-50GeO2-25P2O5) with the FSDP reaching maximum intensity and NGeO = ~5. Here, this model gets support by considering the detailed fractions of the structural groups which exist at the corresponding glass stoichiometry. Structures similar to this model are not known of the crystalline germanophosphate compounds.

Abstract: Relaxation of diffuse-scattering intensities of various kinds of waves is a phenomenon of an especial interest since its study enables one to obtain the most detailed information on both the equilibrium short-range order (SRO) and the non-equilibrium SRO, and therefore, it is the most convenient instrument for investigating SRO kinetics. The SRO kinetics is studied by the use of available data of measurements of residual electrical resistivity for substitutional f.c.c.-Ni–Al solid solutions during their isothermal annealing. Within the framework of the first-order and (more realistic) second-order kinetics models, the maximum characteristic relaxation times and equilibrium magnitudes of the residual electrical resistivity for these solid solutions at different annealing (1273–1626 K) and quenching temperatures (≥ 1723 K) are evaluated, and the hypothetical values of similar quantities appropriate for the diffuse scattering of radiations are estimated too.

Abstract: In order to develop an economical production method of high Si steel sheet, 6%Si (by weight percent, unless specified otherwise) steel was prepared by a combined process of conventional casting and hot- and cold-rolling. Tension and nano-hardness tests and TEM analysis were carried out to examine the effects of ordered phases, Si-content, and testing temperature on cold workability. By optimizing the successive processes of casting, hot-rolling, heat treatment, and cold-rolling, 0.5 mm thick 6%Si steel sheet was successfully produced without crack formation. As Si content increased from 3% to 6%, core loss (W10/50) of the 0.5 mm thick Si steel sheet decreased from 1.36 W/kg to 0.89 W/kg.

Abstract: Effect of isothermal aging on martensitic transformation temperatures, mechanical properties and microstructure was investigated for a Ni-rich Ti-Zr-Ni shape memory alloy at temperatures ranging from 673 K to 773 K. The aging behaviour was two stage process: the first stage associated with an increase in the Vickers hardness and a decrease in martensitic transformation temperatures and the second stage with a decrease in the hardness and increase in the transformation temperatures. Second stage was also characterized by the appearance of nano-scale precipitates, which has never been reported.

Abstract: The use of mechanical spectroscopy to characterize the quasicrystalline state of solid matter is reviewed. After a general, chronological survey of existing mechanical spectroscopy studies, which include elastic properties as well as various relaxation phenomena between lowtemperature tunneling processes and high-temperature background damping, three subjects are considered in more detail: (i) the nature of intrinsic relaxation phenomena, including relaxation peaks in Al-Pd-Mn single quasicrystals, (ii) hydrogen-induced loss peaks in Zr/Ti-based quasicrystals and their use as a probe, and (iii) the study of nano-quasicrystalline structures and amorphousquasicrystalline transitions. It is shown that by combined studies of different elastic and anelastic phenomena, mechanical spectroscopy can be a valuable tool to obtain information about the nature and motion of defects, about the type of local atomic order, and about phase transformations and different processes leading to the formation of quasicrystalline order.