ABSTRACT
Multi-principal element alloys (MPEAs) have been the focus of study and computationally-guided design for two reasons. MPEAs have shown high strengths and, the vast potential compositional space is more efficiently navigated with machine learning. In this article, we present data from 7385 indentation tests performed on 19 different MPEAs. Samples were arc melted, a thermodynamically complex process forming many distinct phases within a sample. The database was generated by performing hundreds of nanoindentation tests on a given sample and registering the location of those indents with local phase compositions measured with energy dispersive spectroscopy (EDS). The database contains the phases formed in the MPEA, the composition at the location of each indent, and the associated hardness (HV) and modulus for each indent. This data allows researchers targeting data-driven design of high strength systems to extract meaningful correlations between alloying composition, the resulting phases, and mechanical properties for future study.
ABSTRACT
BACKGROUND AND OBJECTIVES: General practitioners (GPs) in New South Wales are required to perform annual medical assessments of driving fitness in patients aged 75 years or older. The objective of this study was to understand GPs' attitudes towards driving assessments and to highlight guideline limitations and possible solutions. METHOD: Semi-structured interviews with a sample of 10 GPs were audio-recorded, transcribed and thematically analysed. RESULTS: The key themes that emerged were challenges GPs face with the current driving fitness assessment, techniques used to overcome these challenges, and the process of negotiating with patients. DISCUSSION: The findings highlighted the need for further support of GPs and for more statistical evidence of driving risks. Key areas of uncertainty were applying licence restrictions, calculating the sum of effects of comorbidities and assessment of new patients. This study might prompt consideration of a range of supports to assist GP decision making, as well as contribute to a decision aid for older drivers.
Subject(s)
Automobile Driving , General Practitioners , Aged , Humans , New South WalesABSTRACT
The properties of materials change, sometimes catastrophically, as alloying elements and impurities accumulate preferentially at grain boundaries. Studies of bicrystals show that regular atomic patterns often arise as a result of this solute segregation at high-symmetry boundaries, but it is not known whether superstructures exist at general grain boundaries in polycrystals. In bismuth-doped polycrystalline nickel, we found that ordered, segregation-induced grain boundary superstructures occur at randomly selected general grain boundaries, and that these reconstructions are driven by the orientation of the terminating grain surfaces rather than by lattice matching between grains. This discovery shows that adsorbate-induced superstructures are not limited to special grain boundaries but may exist at a variety of general grain boundaries, and hence they can affect the performance of polycrystalline engineering alloys.
ABSTRACT
The ex situ lift out (EXLO) adhesion forces are reviewed and new applications of EXLO for focused ion beam (FIB)-prepared specimens are described. EXLO is used to manipulate electron transparent specimens on microelectromechanical systems carrier devices designed for in situ electron microscope analysis. A new patented grid design without a support film is described for EXLO. This new slotted grid design provides a surface for holding the specimen in place and also allows for post lift out processing. Specimens may be easily manipulated into a backside orientation to reduce FIB curtaining artifacts with this slotted grid. Large EXLO specimens can be manipulated from Xe+ plasma FIB prepared specimens. Finally, applications of EXLO and manipulation of FIB specimens using a vacuum probe lift out method are shown. The vacuum probe provides more control for placing specimens on the new slotted grids and also allows for easy manipulation into a backside configuration.