Grain Boundary Evolution of Cellular Nanostructured Sm-Co Permanent Magnets

Grain boundaries are thought to be the primary demagnetization sites of precipitate-hardening 2:17-type Sm-Co-Fe-Cu-Zr permanent magnets with a unique cellular nanostructure, leading to a poor squareness factor as well as a much lower than ideal energy product. In this work, we investigated the grain boundary microstructure evolution of a model magnet Sm25Co46.9Fe19.5Cu5.6Zr3.0 (wt. %) during the aging process. The transmission electron microscopy (TEM) investigations showed that the grain boundary region contains undecomposed 2:17H, partially ordered 2:17R, 1:5H nano-precipitates, and a Smn+1Co5n−1 (n = 2, 1:3R; n = 3, 2:7R; n = 4, 5:19R) phase mixture at the solution-treated state. After short-term aging, further decomposition of 2:17H occurs, characterized by the gradual ordering of 2:17R, the precipitation of the 1:5H phase, and the gradual growth of Smn+1Co5n−1 compounds. Due to the lack of a defect-aggregated cell boundary near the grain boundary, the 1:5H precipitates are constrained between the 2:17R and the Smn+1Co5n−1 nano-sheets. When further aging the magnet, the grain boundary 1:5H precipitates transform into Smn+1Co5n−1 compounds. As the Smn+1Co5n−1 compounds are magnetically softer than the 1:5H precipitates, the grain boundaries then act as the primary demagnetization sites. Our work adds important insights toward the understanding of the grain boundary effect of 2:17-type Sm-Co-Fe-Cu-Zr magnets.

Effects of Subthalamic Nucleus Deep Brain Stimulation and Levodopa on Balance in People with Parkinson’s Disease: A Cross Sectional Study

Subthalamic nucleus deep brain stimulation (STN-DBS) and levodopa are common treatment strategies for Parkinson’s disease (PD). However, the specific effects of these treatment strategies on balance and its components remain unclear. This cross-sectional study of people with PD and STN-DBS compared balance in the treated state (ON-medication/ON-stimulation) and untreated state (OFF-medication/OFF-stimulation) using the Balance Evaluation Systems Test (BESTest). Total BESTest scores from the treated and untreated states were compared to assess overall balance. Scores for the six sections of the BESTest were further compared to assess differences in specific components of balance between treatment conditions. Twenty-nine participants were included (Male: 21, Female: 8, Mean Age ± SD: 65.0 ± 6.9). Total BESTest scores showed improved balance in the treated state compared to the untreated state (Treated: 67.56 ± 10.92; Untreated: 59.23 ± 16.51, p < 0.001). Four sections (Stability Limits/Verticality, Anticipatory Postural Reactions, Sensory Orientation, Stability in Gait) of the BESTest significantly improved in the treated state relative to the untreated state, after correcting for multiple comparisons (p < 0.05). These results demonstrate that STN-DBS and levodopa improve overall balance and provide a first step toward understanding the effects of these treatment strategies on specific components of balance.

Creoles of the Mountains: Race, Regionalism, and Modernity in Progressive Era Appalachia

This article investigates how Progressive Era writers, both popular and scientific, helped to construct multiracial identities alongside competing efforts to enshrine race into strictly black and white terms. Existing scholarship on race in the Progressive Era has not sufficiently analyzed the presence of multiracial populations. Instead, scholars have treated state and federal efforts to police racial boundaries, namely through anti-miscegenation laws and the census, as evidence that multiracial persons were a legal impossibility. However, scientific and popular writing on Appalachia provides a conceptual space in which multiracialism was not only a conceptual possibility, but was engendered. Appalachia took on increased importance during the Progressive Era as both intellectuals and reformers used the region to frame their anxieties about the limits of modernity and the threat of racial mixing. The region was home to white mountaineers who appeared arrested in time, existing in uncomfortable proximity to newly discovered groups with white, black, and Native American ancestry who also seemed to have been shunned by civilization. In attempting to understand the peculiar conditions of Appalachia, these Progressive Era writers helped to advance some of the first ideas about what it meant to be mixed-race in America.

Influence of heat treatment on corrosion behavior of laser welded Mg-Gd-Y fusion zones

Purpose This paper aims to evaluate the corrosion resistance of fusion zones in different heat treated condition from laser welded Mg-Gd-Y alloys and analyze their intrinsic corrosion mechanism. Design/methodology/approach The corrosion behavior of fusion zone from laser-welded Mg-Gd-Y alloy joints in the as-welded, ageing and solution + ageing conditions was investigated in the 3.5 wt.% NaCl solution by immersion tests. Findings The corroded surface of as-welded fusion zone consists of dark and bright regions, and the bright regions were composed of high-density needle-like products, whereas some different extended direction of the cracks with lots of long ultrafine needle-shaped corrosion products appeared in the dark regions. The corrosion resistance of the fusion zone is slightly decreased after the ageing treatment. Originality/value The solution + ageing treated fusion zone exhibits the highest corrosion resistance than that of the as-welded and ageing treated state because of the full dissolution of the cathodic coarse eutectic compound, grains growth and relatively compact protective films. The inhomogeneous distribution of the β′ can somewhat improve the corrosion rate of solution + ageing treated fusion zone when compared with base metal.

Corrosion and Oxidation Behavior of a Fe-Al-Mn-C Duplex Alloy

The low-density steels represent a topic of great interest within the scientific world because of the great demand from the steel market of increasingly lighter materials, also featured by an optimal mix of the mechanical properties. In this work, the corrosion and hot oxidation resistance of a Fe-15%Mn-9.5%Al-6.5%Ni-1%Cr-0.43%C were analyzed and related to the microstructural features. The material behavior was analyzed both in the as-cast and in the heat-treated state. For the corrosion test, the experimental plan was fulfilled using four different concentrations of HCl and four temperatures. In the case of hot oxidation resistance, the exposure time and the temperature effects were evaluated. The corrosion resistance in HCl was comparable to the stainless steel, and the iso-corrosion curves showed excellent resistance of the 1300 °C solution-treated material, especially at low temperatures, but it is also good at high temperatures due to the hot oxidation.

Effects of Surface Treatments on the Fatigue Response of High Strength Fasteners

The aim of the present work was the assessment of the impact of deep-rolling and shot-peening performed in the underhead and in the unthreaded shank of two high strength screws (36 NiCrMo and 42 CrMoV) for fatigue life enhancement. The experimental campaign consisted of six combinations, including the non-treated state. The aforementioned treatments were evaluated alone or with shot-peening performed after deep-rolling in the underhead fillet of the screws. Deep rolling was carried out at the optimal rolling force, whereas two shot diameters were considered for shot-peening (Z100 and UFS70). The results have been evaluated in terms of fatigue limits and factor effects have been assessed by marginal mean plots.