A comparative study of the optical properties of TbRhGe and DyRhGe

In this paper, experimental and theoretical optical properties of TbRhGe and DyRhGe have been reported and compared. Our measurements by the ellipsometric method in the wavelength range 0.22–15 μm revealed significant differences in energy positions of the interband peaks in the spectral functions of these ternary compounds. The electronic structure of TbRhGe and DyRhGe calculated within the LSDA + U method was used to obtain theoretical optical conductivity, which is in good agreement with the experimental one. Further analysis allowed us to track changes in interband transitions related to the rare-earth 4f and rhodium 4d states, which are responsible for the observed differences in optical properties of TbRhGe and DyRhGe compounds.     

Exchange bias in bulk Ni-Mn-In-based Heusler alloys

The crystal structure and exchange bias of the bulk Heusler alloys Ni₅₀Mn_50−xIn_x with 14.5?x?15.2 have been investigated using X-ray diffraction and magnetization measurements, respectively. Magnetic measurements were performed with SQUID magnetometry after samples were zero-field cooled and field cooled (FC) in positive magnetic fields up to H=50 kOe, from a temperature T=380 K. Three temperatures of the phase transitions, T₁<T_M<T_C, and a shift of the FC (50 kOe) magnetic hysteresis loops up to 120 Oe at 5 K have been detected for all samples. The exchange bias field (H_E) was almost constant for intermediate In concentrations 14.8<x<15.2, and sharply decreased to about 20 Oe on the borders of this concentration interval (x?14.5; 15.2?x). The changes of H_E have been related to changes in the ratio of T₁ to T_M: the overlapping of transitions at T₁ and T_M (for x=14.8, and 15.2) results in a decrease in H_E.     

Erfahrungen bei der Anwendung der 85Kr-Methode zur Temperaturmessung an Motorkolben

Am Beispiel von Untersuchungen am Kolben eines Dieselmotors wird ein Verfahren der Bestimmung maximaler Temperaturen beschrieben, welche in dem Element auftreten, das mit Hilfe des Isotops ⁸⁵Kr markiert ist. Die Brauchbarkeit dieses Verfahrens für die Motoruntersuchungen wurde nachgewiesen, sowie die Möglichkeiten seiner Anwendiung bei der Korrelation der Verteilung maximaler Temperaturen im Kolben mit dem Motorverschleiß und besonders mit dem Spiel-zwischen dem Kolben und dem Zylinder und den Einstellungen der Einspritzapparatur.     

Cl-对Zn-Ni合金共沉积Zn转移电流密度的影响

在氯化物电解液中Zn_Ni合金共沉积存在着由正常共沉积转变成异常共沉积的Zn转移电流密度 ,该转移电流密度随着Cl-浓度的增加而增加 ,而与溶液pH值基本无关 .这是由于Cl-的存在降低了Ni的析出过电位 ,并对Ni的析出有催化作用之故     

Application of diffusion couple technique for the determination of the Ti‐Bi‐Sn phase diagram

The system Ti‐Bi‐Sn has been investigated by solid/liquid diffusion couples at 500, 600, 700 and 800°C. A non‐negligible solubility of Sn into solid Bi is found. Diffusion layers of the recently revealed ternary compound Ti₃BiSn have been observed, thus its existence has been confirmed. Data about the homogeneity ranges of the binary end‐system compounds have been obtained. The assessed growth constants of the diffusion layers are comprised in the interval 10^‐12 –10^‐14 m².s^‐1. The phases participating in the hypothetical ternary eutectic reaction, probably are: (Bi), (Sn), Liquid and Ti₂Sn₃. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Guaranteed Behavior in Shape Memory Alloys. Short- and long-time effects related to temperature and phase coexistence

A phenomenological approach, in the parent phase of Cu-Zn-Al shape memory alloy, establishes a predictable model (or mathematical equations) relating the dependence of Ms with the temperature over a long period of time (i.e. seasonal or yearly room temperature). High-resolution resistance and temperature measurements vs. time are used. The long time Ms tracks the external room temperature via two temperature dependent time constants. In steady state, the changes in Ms approach17 per cent of the ‘room’ temperature change. The detailed analysis shows the puzzling disappearance of the after quench effects. This revised version was published online in July 2006 with corrections to the Cover Date.     

NANOSTRUCTURED AND AMORPHOUS MATERIALS BY MECHANICAL ALLOYING

Mechanical Alloying is particularly attractive because it can be used to process structurally uniform and isotropic bulk quantities of powdered materials that have a fine length scale. Furthermore, it appears to be applicable to many combinations of elements. Here experimental results regarding the synthesis and characterization of several binary and ternary nanocrystalline and amorphous alloys of Ti, Zr, Hf, V, Nb and Fe with other transition elements and with B, C and Si are reported. The nanocrystalline and amorphous powders, with effective particle size between 7 and 30nm, were prepared by mechanical alloying in a high-energy ball-mill using commercial elemental powders and/or alloy powder.     

一种引人注目的新材料——形状记忆合金

描述了形状记忆合金的基本实用特性,并从力学的观点介绍了对认识过程以及可遂马氏体相变过程,描绘了合金的形状记忆效应,变形引发相变,回复应力,超塑性和双向记忆效应。