Social networks and regional recruitment of foreign labour: Firm recruitment methods and spatial sorting in Denmark*

This paper tests the hypothesis that social networks are crucial for regional recruitment and inflows of foreign labour. New survey data on 971 firms located in Region Southern Denmark show that the predominant recruitment method of foreign labour was through networks. Danish municipal data from 1997–2006 furthermore reveal spatial sorting since initial shares of employees with a foreign background out of total regional employment predict foreign labour inflow rates to regional employment. Thus, social networks appear crucial for the recruitment and inflows of foreign labour, suggesting that employee referrals and information about vacancies in local job markets are also important for foreign labour. Resumen Este artículo pone a prueba la hipótesis de que las redes sociales son cruciales para la contratación regional y los flujos de mano de obra extranjera. Nuevos datos de una encuesta sobre 971 empresas ubicadas en la Región de Dinamarca Meridional muestran que el método de contratación predominante de mano de obra extranjera fue a través de redes. Datos municipales daneses de 1997‐2006 revelan además una clasificación espacial, ya que las cuotas iniciales de empleados de origen extranjero respecto del empleo regional total predicen tasas de afluencia de mano de obra extranjera para el empleo regional. Por tanto, las redes sociales parecen ser cruciales para el reclutamiento y la afluencia de mano de obra extranjera, lo cual sugiere que las referencias de los empleados y la información sobre ofertas de empleo en los mercados laborales locales son también importantes para la mano de obra extranjera.      

Nanoscale Oxide Formation at α-Al2O3–Nb Interfaces

Parts for metallurgical applications made from refractory metal–ceramic composites offer improved thermal shock resistance due to their capability for resistive heating compared to ones made solely from ceramics such as Al₂O₃. The combination of Al₂O₃ and Nb is intriguing as both show similar thermal expansion behavior over a wide temperature range. The high affinity of Nb for O to form nonprotective oxides, however, hampers its use in oxidative environments. Formation of such phases at the ceramic–metal interface can have detrimental effects on the cohesion of the composites. For this work, nanocrystalline Nb films are deposited on sapphire substrates by magnetron sputtering to study diffusion of O and high-temperature phase formation at a refractory metal–ceramic interface during heat treatment under Ar at 1600 °C. A combined approach of atom probe tomography and transmission electron microscopy for compositional and crystallographic analyses reveals that at triple junctions of the sapphire–Nb interface with Nb grain boundaries, heterogeneous nucleation of nanoscale NbO₂ occurs, which further reacts with Al₂O₃ to form AlNbO₄, while the Nb film itself remains metallic. Fast O transport through grain boundaries leads to internal oxidation at the interface, whereas regions further away from Nb grain boundaries remain unchanged.     

Recycling-Induced Copper Contamination of a 42CrMo4 Quench and Tempering Steel: Alterations in Transformation Behavior and Mechanical Properties

The transformation behavior and the mechanical properties of three laboratory produced steels are presented. To investigate the influence of copper contamination, the reference alloy 42CrMo4 is modified and alloyed with 0.5 and 1.0 wt% copper, respectively. The transformation behavior is investigated through dilatometry that yields continuous cooling transformation diagrams, while the mechanical properties are investigated by hardness measurements as well as Charpy-V-notch impact and tensile tests. Accompanying microstructure investigations by means of light optical, scanning electron, and transmissions electron microscopy and thermodynamic simulations (CALPHAD) are performed. It is demonstrated that copper contamination that will be unavoidable when increasing the overall steel recycling fraction may contain the potential for increasing the hardness as well the strength of standard high strength steels, although it is considered to be very detrimental during steel production. Together with reduced environmental footprints and production costs due to the utilization of lower grade scrap with more Cu-contamination, the development of alternative processing routes for Cu-contamination-tolerant high strength steels is pursued.