Effect of manganese on sintering processes in the Ti-Fe system

Conclusions The behavior of Ti-Fe-Mn specimens under conditions of sintering at temperatures above the eutectic point is analogous to that of Ti-Fe and Ti-Fe-Ni specimens: The changes in the linear dimensions of compacts and the magnitude of exothermic effects depend on the rate of heating to the sintering temperature. At high rates of heating the linear dimensions of Ti-Fe-Mn specimens change in a stepwise manner (their shrinkage decreases). During slow heating a decrease in the shrinkage of Ti-Fe-Mn specimens, unlike that of Ti-Fe and Ti-Fe-Ni specimens, is followed by its increase.Translated from Poroshkovaya Metallurgiya, No. 1(277), pp. 15–18, January, 1986.     

Nb添加对Nd-Ce-Fe-B合金的磁性能及晶间交换耦合作用的影响

研究了不同含量的Nb添加对(Nd_0.5Ce_0.5)₁₃Fe_82-xNb_xB₅快淬合金的磁性能、物相组成、交换耦合作用及其初始磁化机制的影响.发现Nb添加能抑制α-Fe的形成,显著改善合金的磁性能.当Nb的添加量(原子分数)为0.5%时,合金获得较优的磁性能.随着Nb的添加量(原子分数)从0增加到0.5%,合金的矫顽力由未添加时的777 kA/m提升到900 kA/m, 最大磁能积也从未添加Nb时的64 kJ/m3增加到78 kJ/m3,而合金的剩磁仅由未添加Nb时的0.71 T轻微下降到0.70 T.合金中晶粒间的交换耦合作用随着Nb的添加而增强.合金的初始磁化机制也有了显著地变化.      

Internal friction in diamagnetic copper and lead polycrystals in a DC magnetic field

The amplitude-dependent internal friction of diamagnetic copper and lead polycrystals 99.9% pure has been studied experimentally in dc magnetic fields with an induction 0 ≤ B ≤ 0.75 T. In a dc magnetic field B = 0.1 T at room temperature, the sign inversion (from plus to minus) of internal-friction increments ΔQ ^?1(B) = Q ^?1(B) ? Q ^?1(0) is revealed for two copper samples. The copper contained impurity-pinned dislocations at ΔQ ^?1(B) > 0 and impurity-free dislocations at ΔQ ^?1(B) < 0. The positive sign of ΔQ ^?1(B) for the internal friction in copper is due to a decrease in the potential-barrier height U _b for dislocation motion in impurity-containing metals. The negative sign of ΔQ ^?1(B) for the internal friction in copper is due to a simultaneous decrease in the barrier height U _b and width (activation volume Θ) during dislocation motion in impurity-containing metals. For a magnetic field B = 0.1 T, the sign of ΔQ ^?1(B) in lead is positive at temperatures below 70°C and the sign of ΔQ ^?1(B) is negative at temperatures above 70°C. For lead, the sign inversion of ΔQ ^?1(B) is explained by the dissolution of dislocation impurity atmospheres at temperatures higher than 70°C.     

Interventional magnetic resonance. Initial clinical experience with a 1.5-tesla magnetic resonance system combined with c-arm fluoroscopy

In our studies on diurnal 6-sulphatoxymelatonin (aMT6s) rhythms in various species, we have sometimes obtained fluctuating patterns. In most of these, the volume of individual urine fractions was not accurately measured because of methodological problems. Here, we report a simple method to overcome these problems by using urinary creatinine to estimate urine volume. The benefit of this method is demonstrated in two representative examples of the diurnal aMT6s rhythms of rats, domestic pigs and humans. Because the human urine fractions were collected accurately, the qualitative pattern of the aMT6s rhythm was not altered by using urinary creatinine as a substitute for urine volume. The total creatinine excretion (urine volume x creatinine concentration) was constant within a small range and showed no diurnal rhythm. In rats and pigs, the highly variable aMT6s concentrations relative to urine volume throughout the 24-hr period were changed drastically by referring to creatinine. All aMT6s patterns became stable and qualitatively similar to those of the rest of the group. From these results it can be concluded that creatinine is an adequate substitute for urine volume and a beneficial parameter with which to overcome technical problems with urine collection from laboratory animals or unknown urine volumes in human studies.