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ThMn12 nitrides are good candidates for high performance permanent magnets. However, one of the remaining challenges is to transfer the good properties of the powder into a useful bulk magnet. Thus, understanding the denitrogenation process of this phase is of key importance. In this study, we investigate the magnetic and structural stability of the (Nd0.75,Pr0.25)1.2Fe10.5Mo1.5Nx compound (x=0 and 0.85) as function of temperature by means of neutron powder diffraction. Thermal dependence of the lattice parameters, formation of α-(Fe,Mo), as well as the nitrogen content in the nitrides are investigated by heating the compounds up to 1010 K. The decomposition takes place mainly via the formation of the α-(Fe,Mo) phase, which starts at around 900 K, whereas the nitrogen remains stable in the lattice. Additionally, we show that the magnetic properties of the nitrides [M(4T)=90Am2/kg and Hc=0.55 T] are maintained after the thermal treatments up to 900 K. This study demonstrates that the ThMn12 nitrides with the Mo stabilizing element offer good prospects for a bulk magnet provided an adequate processing route is found., The authors acknowledge the project “SpINS: Spanish Initiatives on Neutron Scattering,” funded by the Spanish Ministry of Science and Innovation, and the CSIC for the neutron beam time granted on the “CRG-D1B.” Institut Laue-Langevin (ILL) is also acknowledged. We are also thankful for technical and human support provided by SGIker (UPV/EHU) and particularly the services of X-Ray Molecules and Materials (Dr. Aitor Larrañaga Varga) and Magnetic Measurements (Dr. Iñaki Orue). This work has received funding from the European Union’s Horizon 2020 research and innovation program under Grant Agreement No. 686056 (NOVAMAG).

On the nanoscale, CoO can have different polymorph crystal structures, zinc blende and wurtzite, apart from rock salt, which is the stable one in bulk. However, the magnetic structures of the zinc blende and wurtzite phases remain virtually unexplored. Here we discuss some of the main parameters controlling the growth of the CoO wurtzite and zinc blende polymorphs by thermal decomposition of cobalt (II) acetylacetonate. In addition, we present a detailed neutron diffraction study of oxygen deficient CoO (CoO0.70–0.75) nanoparticles with zinc blende (∼15 nm) and wurtzite (∼30 nm) crystal structures to unravel their magnetic order and its temperature evolution. The magnetic order of the zinc blende nanoparticles is antiferromagnetic and appears at the Néel temperature TN ∼ 203 K. It corresponds to the 3rd type of magnetic ordering in a face-centered cubic lattice with magnetic moments aligned along a cube edge. The magnetic structure in the wurtzite nanoparticles turned out to be rather complex with two perpendicular components. One component is incommensurate, of the longitudinal spin wave type, with the magnetic moments confined in the ab-plane. In the perpendicular direction, this magnetic order is uncorrelated, forming quasi-two-dimensional magnetic layers. The component of the magnetic moment, aligned along the hexagonal axis, is commensurate and corresponds to the antiferromagnetic order known as the 2nd type in a wurtzite structure. The Néel temperature of wurtzite phase is estimated to be ∼109 K. The temperature dependence of the magnetic reflections confirms the reduced dimensionality of the incommensurate magnetic order. Incommensurate magnetic structures in nanoparticles are an unusual phenomenon and in the case of wurtzite CoO it is probably caused by structural defects (e.g., vacancies, strains and stacking faults)., This work was supported by the Russian grant RFBR 16-02-00058, the MAT2016-79455-P and MAT2015-68200-C2-2-P projects of the Spanish MINECO and by the 2017 SGR 292 and 2017 SGR 776 projects of the Generalitat de Catalunya. The ICN2 is supported by the Severo Ochoa Centres of Excellence programme funded by the Spanish Research Agency(AEI, grant no. SEV-2017-0706). ALO acknowledges the Juan de la Cierva Program (MINECO IJCI-2014-21530).

Microindentation measurements are reported on a range of single polymer polyethylene (PE) composites, which are produced by hot compaction of high modulus PE fibers. It is possible to measure two hardness values, parallel and perpendicular to the fiber direction respectively, from which the microindentation anisotropy is defined. The hardness values relate to the instantaneous elastic recovery of the fibers, and the results show that the microindentation measurement is deforming a material volume below the surface of the sheets comparable to the dimensions of the fibers. It appears that the microindentation anisotropy approaches a limiting value with increasing fiber orientation, i.e., as the Young's modulus of the fibers increases. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1659–1663, 2006

4 pags., 5 figs., 2 tabs., Ultra-microindentation was used to measure the microhardness and modulus of silk (Bombyx mori) membranes, cast from 20 to 80°C. The microhardness and modulus were determined from the loading/unloading curves. The membranes exhibit microhardness of about 400 MPa which is larger than the values for most common synthetic polymers (50-300 MPa) implying a greater scratch resistance. The moduli are of the order of those measured by the other means for B. mori silk membranes (5 GPa), and fibers (7-11 GPa). There is some correlation between microhardness and the dimensions of the grains/nanofibrils, but none with surface roughness. The results extend the range of an empirical correlation between microhardness and modulus. The present data together with previous data from other polymers fit the equation, H=0.55E0.74, with a correlation coefficient of 0.94. Finally, it is shown that elastic recovery of the silk membranes is an increasing function of the maximum load applied. © 2004 Elsevier Ltd. All rights reserved., This work was supported in part by Air Force Office of Scientific Research (AFOSR) Award number F49620-03-1-0169. Grateful acknowledgement is due to MCYT (grantBFM2000-1474) for the support of this investigation. Oneof us, I.P.O., also acknowledges the support of the FPIProgramme of MCYT (Spain).

Procedures based on equilibrium conditions (stress and bending moment) have been used to obtain an unstressed lattice spacing, d0, as a crucial requirement for calculating the residual stress (RS) profile across a joint conducted on a 10 mm thick plate of age-hardenable AA2024 alloy by friction stir welding (FSW). Two procedures have been used that take advantage of neutron diffraction measurements. First, equilibrium conditions were imposed on sections parallel to the weld so that a constant d0 value corresponding to the base material region could be calculated analytically. Second, balance conditions were imposed on a section transverse to the weld. Then, using the data and a genetic algorithm, suitable d0 values for the different regions of the weld have been found. For several reasons, the comb method has proved to be inappropriate for RS determination in the case of age-hardenable alloys. However, the equilibrium conditions, together with the genetic algorithm, has been shown to be very suitable for determining RS profiles in FSW joints of these alloys, where inherent microstructural variations of d 0 across the weld are expected. © Published by Elsevier Ltd. All rights reserved., Support from Projects MAT-05-0527 and MAT-09-09545 from MICINN, and PIE 200960I076 from C.S.I.C., Spain, is gratefully acknowledged. Financial help from the ILL to conduct the neutron diffraction measurements on SALSA, experiments 1-02-6 and 1-02-10, is recognized. Support from Spanish Government Grants TIN 2008-00508 and MEC CONSOLIDER CSD00C-07-20811 and from Spanish MINECO (projects MAT2011-23455 and MAT2011-25991) is also acknowledged by J.I.H. and I.P.O., respectively.

17 pags., 7 figs., The present work is concerned with the study of the development of the crystalline structure of poly(ethylene terephthalate) in multilayered films of poly(ethylene terephthalate)/polycarbonate (PET/PC) prepared by means of layer multiplying coextrusion. Small angle X-ray scattering patterns were recorded during isothermal crystallization experiments and evaluated by means of Ruland's interface distribution function. Thus, structural parameters describing the thickness distribution of crystalline and amorphous layers were determinated. It is shown that the crystallization of PET is delayed with increasing confinement. However when the crystallization process comes to an end, the values of the nanostructural parameters of the lamellar system are nearly the same for the confined and non-confined PET. © 2009 Elsevier Ltd.

European Discussion Meeting on Polymer Physics; Semicrystalline Polymers: Structure Formation and Properties, Alemania, 24 September 2003, he microhardness H of multilayered poly(ethylene terephthalate) (PET)/polycarbonate (PC) films, produced by continuous layer multiplying coextrusion has been determined. These materials present rather uniform laminates up to thousands of layers in the micrometre and submicrometre range. The micromechanical properties have been investigated as a function of layer thickness of the single polymer components, the total number of layers, the film thickness and the influence of heat treatment. The microhardness of the microlayered structure has also been determined across the profile in the parallel direction to the packing of the layers. The hardness in the vicinity of the PET/PC phases has been examined. Results reveal that the influence of the interphase on the H values for the samples with a large number of layers is rather small. The most important parameter in determining the final hardness of the multilayered films is the ratio of the penetration depth to the thickness of the layer. Upon heating, a microhardness increase is observed as a consequence of a double contribution: the crystallization of the PET layers, on the one hand, and the physical ageing of the PC zones on the other.