Thermal induced structural and magnetic transformations in Fe_{73.5−x}Ce_{x=0,3,5,7}Si_{13.5}B_9Nb_3Cu_1 amorphous alloy

Structural and magnetic properties of amorphous and partly crystallized Fe_{73.5−x}Ce_{x=0,3,5,7}Si_{13.5}B_9Nb_3Cu_1 alloys, were analysed in the temperature ranging from RT to 800 °C with scanning calorimetry and magnetometry. The Fe(Si) and Fe(B) structures were identified and characterised with set of crystallization temperatures and activation energies. Also, Curie temperatures for amorphous and for crystalline structures were determined and analysed as functions of Ce content

The structural stability of soft magnetic Fe-Co-Zr-W-B metallic glasses investigated by the in-situ XRD

The atomic structure of as-prepared $Fe_{61}Co_{(14-x)}Zr_{5}W_{x}B_{20}$ (x=1, 2 and 4) ribbon samples and their thermal stability were investigated by in-situ high-energy X-ray diffraction experiments. It was observed that higher W concentration causes the tiny shift of the main peak of the reduced atomic pair distribution function to higher values of interatomic distances and increases the coefficient of volume thermal expansion. The crystallization process occurs in two steps and is qualitatively the same for all studied specimens. Firstly the $Fe_{23}B_{6}$ phase is created and later is transformed to other types of borides together with the creation of a Fe-based phase

Structural and Magnetic Properties of Mechanically Alloyed Fe-Co Powders

The Fe-Co alloys are well known as ferromagnetic materials exhibiting high values of saturation magnetization, Curie temperature and magnetostriction. In powder form they are commonly used in the magnetic recording media. In this paper the structural and magnetic properties of a series of Fe-Co alloy powders prepared by mechanical alloying are presented. The Fe-Co powders (with 30, 45, 50 and 60 wt. % of Co) were prepared by mechanical alloying of high purity powder elements mixture in a planetary ball mill (Retsch PM 4000). The milling of all samples was performed in argon atmosphere with the ball-to-powder weight ratio of 15:1 and the speed of 180 rpm for 30 hours. The X-ray diffraction investigations show, that the alloying of fcc-Co into bcc-alpha-Fe took place during the milling, leading to the formation of the bcc-FeCo solid solution. It was found, that the lattice parameter (with values from 0.2861 nm to 0.2866 nm) of the investigated mechanically alloyed Fe-Co samples is larger for samples containing higher concentration of Co. The process of mechanical alloying was confirmed by Mössbauer spectrometry. The structure and powder size were observed by both TEM and SEM investigations. The coercivity (with values from 2.4 kA m-1 to 3.9 kA m-1) of the powders (measured by a Förster Koerzimat at room temperature) containing higher Co content exhibit larger values.JRC.F.4-Nuclear design safet

Soft x-ray free-electron laser induced damage to inorganic scintillators

An irreversible response of inorganic scintillators to intense soft x-ray laser radiation was investigated at the FLASH (Free-electron LASer in Hamburg) facility. Three ionic crystals, namely, Ce:YAG (cerium-doped yttrium aluminum garnet), PbWO4 (lead tungstate), and ZnO (zinc oxide), were exposed to single 4.6 nm ultra-short laser pulses of variable pulse energy (up to 12 μJ) under normal incidence conditions with tight focus. Damaged areas produced with various levels of pulse fluences, were analyzed on the surface of irradiated samples using differential interference contrast (DIC) and atomic force microscopy (AFM). The effective beam area of 22.2 ± 2.2 μm2 was determined by means of the ablation imprints method with the use of poly(methyl methacrylate) - PMMA. Applied to the three inorganic materials, this procedure gave almost the same values of an effective area. The single-shot damage threshold fluence was determined for each of these inorganic materials. The Ce:YAG sample seems to be the most radiation resistant under the given irradiation conditions, its damage threshold was determined to be as high as 660.8 ± 71.2 mJ/cm2. Contrary to that, the PbWO4 sample exhibited the lowest radiation resistance with a threshold fluence of 62.6 ± 11.9 mJ/cm2. The threshold for ZnO was found to be 167.8 ± 30.8 mJ/cm2. Both interaction and material characteristics responsible for the damage threshold difference are discussed in the article

Investigating the interaction of x-ray free electron laser radiation with grating structure

The interaction of free electron laser pulses with grating structure is investigated using 4.6±0.1 nm radiation at the FLASH facility in Hamburg. For fluences above 63.7±8.7 mJ/cm2, the interaction triggers a damage process starting at the edge of the grating structure as evidenced by optical and atomic force microscopy. Simulations based on solution of the Helmholtz equation demonstrate an enhancement of the electric field intensity distribution at the edge of the grating structure. A procedure is finally deduced to evaluate damage threshold