Microstructure evolution of Al-15% Si alloy during hot rolling

ABSTRACT

A direct chill (DC) cast Al-15% Si alloy was processed by hot rolling with a single pass at a temperature of 520°C with a thickness reduction of 80%. Scanning electron microscopy (SEM), electron backscattering diffraction (EBSD) and transmission electron microscopy (TEM) were used to investigate the evolution of the sample’s microstructure. After hot rolling, silicon particles homogeneously distributed in the Al matrix with fine equiaxed grains of average size ～ 0.95?μm. High-angle boundaries (HABs) (about ～75.8% in percentage) dominate in the Al matrix structure. There is evidence for Si-particle-stimulated continuous dynamic recrystallization (CDRX) during hot rolling.     

Observations of copper clustering in a 25Cr-7Ni super duplex stainless steel during low-temperature aging under load

Atom-probe tomography was used to investigate phase separation and copper (Cu) clustering in the ferrite phase of a 25Cr-7Ni super duplex stainless steel. The steel was subjected to a tensile load during aging at 325°C for 5800?h. The degree of phase separation into α (Fe-rich) and α′ (Cr-rich) was small, but still, it was the highest in the steel subjected to the highest load. Cu was found to cluster, and the number density of clusters increased with increasing load. In the material subjected to the highest load, Cu was enriched in regions that were neither Fe-rich nor Cr-rich. These regions also had the highest number density of Cu clusters.     

Surface tension measurement of undercooled liquid Ni-based multicomponent alloys

The surface tensions of liquid ternary Ni–5%Cu–5%Fe, quaternary Ni–5%Cu–5%Fe–5%Sn and quinary Ni–5%Cu–5%Fe–5%Sn–5%Ge alloys were determined as a function of temperature by the electromagnetic levitation oscillating drop method. The maximum undercoolings obtained in the experiments are 272 (0.15T _L), 349 (0.21T _L) and 363?K (0.22T _L), respectively. For all the three alloys, the surface tension decreases linearly with the rise of temperature. The surface tension values are 1.799, 1.546 and 1.357?N/m at their liquidus temperatures of 1719, 1644 and 1641?K. Their temperature coefficients are ?4.972?×?10^–4, ?5.057?×?10^?4 and ?5.385?×?10^?4?N/m/K. It is revealed that Sn and Ge are much more efficient than Cu and Fe in reducing the surface tension of Ni-based alloys. The addition of Sn can significantly enlarge the maximum undercooling at the same experimental condition. The viscosity of the three undercooled liquid alloys was also derived from the surface tension data.     

Study on the deformation of nanocrystalline cobalt

A study was carried out on the deformation of nanocrystalline cobalt. For cold-rolled nanocrystalline cobalt, the X-ray diffraction peaks narrowed instead of broadened on deformation. The results of transmission electron microscopy showed that grain size (17.8?nm on average) was not increased. The results can be explained in terms of the production and activity of vacancies and vacancy clusters.     

Effect of V addition on the structure of ZrCr2 Laves phase: a high-resolution transmission electron microscopy study

The structures of the binary ZrCr₂ and ZrCr₂ Laves phase with addition of V have been investigated by high-resolution transmission electron microscopy (HRTEM). The results show that annealed ZrCr₂ is the cubic C15 phase with micro-twins. In contrast, annealed Zr(CrV)₂ has a lamellar microstructure with a character of long-period stacking sequences. Further studies by HRTEM indicate that annealed Zr(CrV)₂ is the di-hexagonal C36 with a coalescence of 5-, 6- and 8-layer long-period stacking structures. The effect of V addition on the structural stability of ZrCr₂ is discussed.     

Temporal Changes in Mood Repair Through Music Consumption: Effects of Mood,Mood Salience,and Individual Differences

Prior research on mood management through media consumption has encountered mixed results. This study seeks to address these discrepancies by incorporating time of measurement into the examination of regulatory outcomes and by identifying trait-like cognitive moderators that presumably are involved in the regulation of negative moods. Results showed that sad mood initially fostered longer listening to mood-compatible music but such preference decreased over time, suggesting the merits of considering temporal changes in the mood-repair process. In addition, ruminative trait was found to be a significant factor in how people cope with their sad moods, whereas mood salience was not.     

Work flow policy and within-worker and between-workers variability in performance

Work flow policies are shown to induce a change in average between-workers variability (worker heterogeneity) and within-worker variability in performance times. In a laboratory experiment, the authors measured the levels of worker heterogeneity and within-worker variability under an individual performance condition, a work sharing condition, and a fixed assignment condition. The work sharing policy increased the levels of worker heterogeneity and worker variability, whereas the fixed assignment policy decreased them. These effects, along with work flow policy main effects on mean performance times and variability are examined. This article represents an initial step in understanding effects that may be important in the selection of an operating policy, the ignorance of which may lead to costly misestimates of performance.     

The roles of familial alcoholism and adolescent family harmony in young adults' substance dependence disorders: mediated and moderated relations

This study examined the prospective relations among family history density of alcoholism (FHD), adolescent family harmony, and young adults' alcohol and drug dependence. Family harmony was rated by mothers and fathers in adolescence, and young adults' substance dependence diagnoses were obtained through structured interviews. Higher FHD predicted lower adolescent family harmony, which in turn increased young adults' odds of being diagnosed with drug dependence (with and without alcohol dependence) compared to no diagnoses or to alcohol dependence only. Family harmony also interacted with FHD such that the protective effect of family harmony on young adults' drug dependence with or without alcohol dependence decreased as FHD rose, and was nonsignificant at high levels of FHD. The findings suggest the importance of distinguishing among alcohol and drug dependence disorders and examining their differential etiological pathways, and also suggest that the protective effects of harmonious family environments on substance dependence may be limited at high levels of FHD.     

道家的"两行"和禅宗的"一行"--论冯友兰先生对"两行"的错误理解

本文从冯友兰先生对"两行"的理解谈起,对"两行"的出处、思想根源和修养方法进行了分析,并据此将道家与禅宗的最高境界进行对照,得出了冯友兰先生的理解是错误的结论.