Table of contents

This issue of IOP Conference Series: Materials Science and Engineering, contains manuscripts of talks that will be presented at the 5th International EEIGM/AMASE/FORGEMAT Conference on Advanced Materials Research that will be held at the Ecole Européenne d'Ingénieurs en Génie des Matériaux – European School of Materials Science and Engineering (EEIGM) in Nancy on November 4–5 2009. The conference will be organized by the EEIGM.

The aim of the conference is to bring together scientists from the six European universities involved in the EEIGM and in the ''Erasmus Mundus'' AMASE Master (Advanced Materials Science and Engineering) programmes and in the Tempus FORGEMAT European project: Nancy-Université – EEIGM/INPL (Nancy, France), Universität des Saarlandes (Saarbrücken, Germany), Universitat Politècnica de Catalunya – ETSEIB (Barcelona, Spain), Luleå Tekniska Universitet (Luleå, Sweden), Universidad Politecnica de Valencia – ETSII (Valencia, Spain) and AGH University of Science and Technology, (Kralow, Poland). This conference is also open to other universities who have strong links with the EEIGM and it will provide a forum for exchange of ideas, cooperation and future directions by means of regular presentations, posters and a round-table discussion.

After careful refereeing of all manuscripts, equally shared between the four editors, 26 papers have been selected for publication in this issue. The papers are grouped together into different subject categories: polymers, metallurgy, ceramics, composites and nanocomposites, simulation and characterization. The editors would like to take this opportunity to thank all the participants who submitted their manuscripts during the conference and responded in time to the editors' request at every stage from reviewing to final acceptance.

The editors are indebted to all the reviewers for painstakingly reviewing the papers at very short notice. Special thanks are called for the sponsors of the conference including EEIGM-INPL, Grand Nancy, Ville de Nancy, Region Lorraine, Université Franco-Allemande and Institut Jean Lamour.

Proceedings Editors: Zoubir Ayadi, Thierry Czerwiec, David Horwat and Brigitte Jamart

All papers published in this volume of IOP Conference Series: Materials Science and Engineering have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

The use of polyolefin flexible foams with typical thicknesses between 1 and 3 mm produced by a physical foaming extrusion process is nowadays quite widespread in the packaging sector. Their high flexibility and closed-cell structure allows them to show good energy absorption properties under low loading conditions. Although the compressive response of these materials is well known, the inner microstructure developed during processing induce a high anisotropy that is responsible for their direction-dependent tensile and fracture behaviours. In this work, two different polyolefin-based foams, with densities ranging from 20 to 45 kg/m³, were studied. The induced microstructure anisotropy was characterized by micro-Raman. With this technique, the relative orientations of both crystalline and amorphous phases in the foam's base polymer could be determined and thus related to their mechanical properties measured in the different directions.

The ageing behaviour of stainless steel joints bonded with hot-curing adhesives is crucial for their reliability and durability in engineering applications. In industry, accelerated artificial ageing regimes are combined with short-term mechanical tests to simulate the in-service long-term behaviour and to predict the life time of the adhesive joints. With such a focus on mechanical bond strength, chemical changes in the adhesive are widely disregarded. Hence, neither the very causes for the decreasing performance of the joint nor their relevance for application can be revealed. Reasoning this study, lap shear samples of the stainless steel alloy 1.4376 are bonded with an epoxy-dicyandiamide adhesive and aged artificially under moderate thermo-oxidative (60 °C, dried air) or hydrothermal (60 °C, distilled water) condition. After testing (shear stress-strain analysis), chemical modifications of this adhesive due to ageing are detected on the fracture faces by μ-ATR-FTIR-spectroscopy as function of ageing time and position in the adhesive joint. The results attest high thermo-oxidative stability to these adhesive joints. For hydrothermal ageing, permeating water deteriorates the EP network from the edges towards the centre of the joint via hydrolysis of imine groups to ammonia, amine species and carbonyls.

Thin films (few 10 nm to some μm) of different two-part polyurethane adhesive systems (polyether resins and aromatic isocyanate hardener) are characterised on the native metal surfaces of gold, aluminium, copper and steel, thus acting as a model for the interphase in technically relevant material compounds. It is investigated in how far the curing processes, the resulting chemical structure and the morphology of the polymer films differ from the bulk. The comparison of films on the different metals and with the bulk provides conclusions on the properties of the interphase at polymer-metal contacts. The variation of the film thickness gives access to microstructure gradients. The chemical structure of the films is characterised by IR spectroscopy during curing at room temperature (RT kinetics) and in the cured state. Furthermore, microscopic (e.g. SFM) and additional spectroscopic techniques (e.g. XPS) characterise the films and their surface with respect to morphology, composition, homogeneity and topography. The results reveal specific features in the interphase caused by adhesive interactions, catalysis, phase separation and transport phenomena on the different metal surfaces. Remarkable quantitative differences can be seen in the chemical structure formation of thin PU films with respect to reaction rate and final degree of cure.

During the last few years several research groups have focused on the fabrication of artificial gecko inspired adhesives. For mimicking these structures, different polymers are used as structure material, such as polydimethylsiloxanes (PDMS), polyurethanes (PU), and polypropylene (PP). While these polymers can be structured easily and used for artificial adhesion systems, the effects of repeated adhesion testing have never been investigated closely. In this paper we report on the effect of repeated adhesion measurements on the commercially available poly(dimethylsiloxane) polymer kit Sylgard 184 (Dow Corning). We show that the adhesion force decreases as a function of contact cycles. The rate of change and the final value of adhesion are found to depend on the details of the PDMS synthesis and structuring.

The aim of this study is to determine which compounds are present into drinking water packaged in poly(ethylene terephtalate) bottles and to know the origin of these substances in relationship with the material.

A screening procedure was established for the detection of unknown compounds into bottled water. A panel of water bottles has been tested after exposure to extreme conditions of temperature and UV radiation to accelerate the possible migration of substances.

At the same time, physico-chemical characterization of polymeric material has been performed namely calorimetric analysis, IRTF and low-frequency mechanical spectroscopy. The results thus obtained allow understanding in a better way the migration kinetics of molecules inside the polymer, it means the pollution of the bottled water.

This investigation aims at studying the mechanical and microscopic properties of PET P (polyethylene terephthalate) used for insulators in High Voltage Gas Insulated Substation before a long term physical ageing. For this reason, a basic study to understand the PET behavior in a reference state (before any thermal ageing) is definitely necessary. In a first step, the study focuses on revealing more detailed information about the PET morphology. For this purpose, PET samples have been subjected to special schemes of crystallization. In fact, after being quenched (amorphous state) from the semicrystalline state, the samples were annealed at different temperatures for several times. This controlled crystallization has shown a classical increase of the long period and the crystallinity ratio. The specimens have been characterized by different techniques, namely, differential scanning calorimetry (DSC), mechanical tests, and wide and small angles X scattering (WAXS, SAXS, respectively). The second step deals with the mechanical properties. We have studied closely the thermal effects below and above the glass transition (Tg), then the tensile rate effects during true stress-true strain tests. The mechanical measurements have shown that the Young modulus and the yield stress decrease when the temperature is increased. However, the material is slightly sensitive to the tensile rate below Tg or even unaffected above Tg.

Fine traces of lubricating oil can be discovered in the form of fine debris left on the surface of cold-rolled steel sheets. High resolution mechanical spectroscopy is a sensitive technique for detecting such extremely fine oil traces. It is shown that a characteristic mechanical loss spectrum occurs in the low temperature range (from 180K up to 280K) only in the two following cases, namely (i) if traces of the rolling oil are left on the surface of sheets and (ii) if the clean sheets are covered with a thin film of the rolling oil (or any other natural or mineral oil). It is clearly demonstrated that similar mechanical spectra induced by the presence of oil can be observed in the sub-resonant mechanical spectroscopy if the oil film is deposited on a very soft cellulose neutral substrate. Therefore the behaviour of the oil alone can be obtained with a high resolution. It will be demonstrated that it is possible to assign the mechanical loss phenomena to the steel sheet (like the Snoek-Koster effect above 500K) and oil separately. In particular, it is shown that the low temperature relaxation phenomena do not originate from a specific interaction of the steel surface with oil, as frequently reported in the literature.

Metastable austenitic stainless steels are currently used in applications where severe forming operations are required, such as automotive bodies, due to its excellent ductility. They are also gaining interest for its combination of high strength and formability after forming. The biggest disadvantage is the difficulty to predict the mechanical response, which depends heavily on the amount of martensite formed. The martensitic transformation in metastable stainless steels can be induced by plastic deformation at room temperature. In this research, the martensitic transformation was provoked by means of torsion testing. Several torsion angles were selected to achieve different percentages of martensite at the surface of the specimens. The next step was to evaluate their effect on the fatigue life of the steel. Fatigue testing in the high cycle regime was done at different levels of mean stress. As a conclusion, the presence of martensite in the surface of the specimen led to an increase of the fatigue life when high mean stress was imposed. By contrast, at lower values of mean stress, martensitic transformation has no positive effect on the fatigue life.

Duplex stainless steel (DSS) is a family of steels characterized by two-phase microstructure with similar percentages of ferrite (α) and austenite (γ).Their attractive combination of mechanical properties and corrosion resistance has increased its use in last decades in the marine and petrochemical industries. Nevertheless, an inappropriate heat treatment can induce the precipitation of secondary phases which affect directly their mechanical properties and corrosion resistance. There are few works dealing with the influence of heat treatments on wear behaviour of these steels in the literature. For instances, this paper aims to determine wear kinetic and sliding wear volume developed as a function of heat treatment conditions. Therefore, the samples were heat treated from 850 °C to 975 °C before sliding wear tests. These wear tests were carried out using ball on disk technique at constant sliding velocity and different sliding distances. Two methodologies were used to calculate the wear volume: weight loss and area measurement using a simplified contact model. Microstructural observations showed the presence of sigma phase for all studied conditions. The formation kinetics of this phase is faster at 875 °C and decrease at higher temperatures. Results related to wear showed that the hardness introduced due to the presence of sigma phase plays an important role on wear behaviour for this steel. It was observed also that wear rates decreased when increasing the percentage of sigma phase on the microstructure.

Continuous cooling transformation diagrams of aluminum solid solution decomposition in range of cooling rates 100–1900 °C/h were built for some alloys of Al-Mg-Si-Fe system. Influence of cooling rate and chemical composition on temperatures of start and finish of solution decomposition was determined.

Alumina was joining to the nickel alloy HAYNES ®214™ using a solid-state bonding technique with an intermediate nickel metallic foil. Experimentally, damages and cracks are often observed close to the metal/ceramics interface. Finite element analysis (FEA) using an elastic-plastic-creep model has been extensively developed for predicting the thermomechanical behaviour of assembly. The goal of such modelling is to be able to design optimum interlayer and to use this design information to guide component fabrication. It is critical that the models be validated by comparison with experimental result. In this study, residual stresses distributions in the specimen were characterized experimentally using X-ray diffraction (XRD) and indentation techniques. A good correlation between FEA analysis and experimental results is obtained.

The new concept of surface texturing or surface patterning on austenitic stainless steel by plasma assisted diffusion treatment is presented in this paper. It allows the creation of uniform micro or nano relief with regularly shaped asperities or depressions. Plasma assisted diffusion treatments are based on the diffusion of nitrogen and/or carbon in a metallic material at moderate to elevated temperatures. Below 420°C, a plasma assisted nitriding treatment of austenitic stainless steel produces a phase usually called expanded austenite. Expanded austenite is a metastable nitrogen supersaturated solid solution with a disordered fcc structure and a distorted lattice. The nitrided layer with the expanded austenite is highly enriched in nitrogen (from 10 to 35 at%) and submitted to high compressive residual stresses. From mechanical consideration, it is shown that the only possible deformation occurs in the direction perpendicular to the surface. Such an expansion of the layer from the initial surface of the substrate to the gas phase is used here for surface patterning of stainless steel parts. The surface patterning is performed by using masks (TEM grid) and multi-dipolar plasmas.

The behaviour of hydrothermal degraded 3% molar yttria stabilised zirconia under monotonic spherical indentation has been studied. The investigation is focused mainly on analysing the response under spherical indentation in terms of the transformed monoclinic surface layer that appears after hydrothermal degradation. The mechanisms of damage are ring and cone cracking, similarly as in as sintered specimens. The permanent damage induced in degraded specimens is always larger than in the as sintered specimens. The "plastic" damage measured by the value of the indentation strain in degraded specimens is larger than in as sintered specimens at the same indentation pressure. The critical contact load to induce ring cracking is determined and it is found that in degraded specimens its value is lower than in as sintered specimens. The results are discussed in terms of elastic properties and microstructure of the degraded layer.

Commercially available tetragonal zirconia powder doped with 3 mol% of yttria has been sintered using spark plasma sintering (SPS) and has been investigated for its resistance to hydrothermal degradation. Samples were sintered at 1100, 1150, 1175 and 1600 °C at constant pressure of 100 MPa and soaking for 5 minutes, and the grain sizes obtained were 65, 90, 120 and 800 nm, respectively. Samples sintered conventionally with a grain size of 300 nm were also compared with samples sintered using SPS. Finely polished samples were subjected to artificial degradation at 131 °C for 60 hours in vapour in auto clave under a pressure of 2 bars. The XRD studies show no phase transformation in samples with low density and small grain size (<200 nm), but significant phase transformation is seen in dense samples with larger grain size (>300 nm). Results are discussed in terms of present theories of hydrothermal degradation.

Surface modification with cerium oxide of tetragonal zirconia polycrystals stabilised with 3% molar yttria (3Y-TZP) has been investigated in order to avoid low temperature degradation. The surface modification was performed by annealing 3Y-TZP with surface coated CeO₂ powder at temperatures of 1400 °C and 1500 °C for periods of time up to 10 hours. These heat-treatments diffused cerium up to about 10 μm depth. The bulk fracture toughness, Vickers hardness and Young modulus of the surface modified specimens showed no significant deviation as compared to the non-treated original material. Even the surface mechanical properties measured by penetration curves corresponding to nanoindentations of up to 2 μm depth, did not show significant differences after surface modification. All heat-treatments produced an increase in the surface grain size and a large increase in resistance to degradation.

This paper describes how the preparation and heat treatment of TiC/Si powders influences the phase reactions during firing. The powders are prepared by milling and some effects of powder preparation are discussed. A solid state displacement reaction according to: 3TiC + 2Si → Ti₃SiC₂ + SiC is a priori expected to take place during heat treatment. The firing procedure is investigated with respect to the effect of heat treatment time and temperature on the phases produced, especially Ti₃SiC₂. Samples were heat treated in a graphite lined furnace. Heat treated samples are analysed by x-ray diffraction, scanning electron microscope and energy dispersive spectroscopy. Ti₃SiC₂, TiC and SiC are dominant in the final products. The highest amount of Ti₃SiC₂ is achieved for short holding times (2–4 hours) at high temperatures (1350–1400°C). Ti₃SiC₂ appears to decompose at elevated temperatures or extended times, through a Ti₃SiC₂ → TiC + Si(g) type reaction. The activation energy of Ti₃SiC₂ phase formation is determined to be 289 kJ/mol, using the Mehl-Avrami-Johnson model.

The objective of this paper is to analyze fiber/matrix debond crack growth in unidirectional (UD) composites during high stress cyclic tension-tension loading. High stress loading means that fiber breaks and consecutive fiber/matrix interface debond growth are expected. Fracture mechanics concepts are applied to analyze damage evolution

Failure process of continuous fiber reinforced composite laminates in tension usually starts with appearance of intralaminar cracks. In composite laminates with complex lay-ups and/or under combined loading, intralaminar cracks may develop in plies with different reinforcement directions. A necessary part of mixed mode cracking models is the criterion of failure. For propagation-controlled fracture it is usually formulated in terms of energy release rates and their critical values of the particular composite material. Intralaminar fracture toughness of unidirectionally reinforced glass/epoxy composite was experimentally determined at several mode I and mode II ratios. It is found that the crack propagation criterion, linear in terms of the energy release rates, reasonably well approximates the test results. The determined mixed mode cracking criterion was applied to predict intralaminar crack onset in cross-ply glass/epoxy composite under tensile loading. The predicted crack onset strain values agree with test results at small off-axes angles of the cracking ply (on-axis and 15° off-axis loading), but underestimate crack onset at larger reinforcement angles with respect to the loading direction. The discrepancy is likely to be caused by the deviation of linearity in laminate response before cracking onset in these laminates, related to non-linear shear characteristics of unidirectional plies. The applicability of strength-based fracture criterion for initiation-controlled cracking is discussed.

The composites have drawn considerable interest in the mould processes. The vibrations and fatigue stresses induced in the moulds made evident to characterize the composite HexTOOL^™ under fretting conditions. Fretting is a small-amplitude oscillatory motion between contacting surfaces. The running conditions fretting maps (RCFM) of composite at ambient conditions were established. The influence of different fiber orientations of HexTOOL^™ composite on the wear kinetics was shown. An energy wear approach was developed. According to results of dynamic mechanical analysis (DMA), the viscoelastic properties of composite material were obtained.

Exposing a laminate structure to thermal cycles and to temperatures close to the curing temperature, followed by mechanical fatigue, cause interlaminar and intralaminar cracks leading to degradation of the mechanical properties. The effect of thermal and mechanical fatigue, as well as thermal aging, on carbon fiber composite laminate structures is under study in the present paper.

Metal-containing polymeric nanomaterials were prepared by the two methods: infrared-irradiation pyrolysis and metals reduction from their salts in hydrazine on substrates. The composite consist of polymer matrix with 3d-metal nanoparticles. The structure and morphology of nanocomposites were investigated for the powder samples using X-ray diffraction, scanning and transmission electron microscopy, and Mössbauer spectroscopy (MS). It is shown that technology of preparing the nanocomposite under IR-irradiation is more effective than a thermal treatment under resistance-type heating, as the synergetic effect of influencing IR-radiation and heat leads to faster polymer transformations. The results of MS data comparison for the samples prepared by IR-radiation-stimulated pyrolysis and by means of salt reduction in hydrazine are discussed.

Me-incorporated Zr_0.84Y_0.16 oxide thin films (Me: Cu or Pd) were synthesized by magnetron co-sputtering. The film structural evolution due to metal content increase was shown: Me-doped nanocrystalline yttria stabilized zirconia (YSZ); Me-doped amorphous oxide; metal nanoparticles embedded in the amorphous oxide matrix. Annealing for 2 h at 300°C in air promoted copper oxide formation and the segregation of very fine Pd particles. XANES analysis at the Cu-K edge showed that Cu is bonded to oxygen and Zr(Y) in Cu-doped amorphous oxide; this state was not affected by the thermal treatment. XANES and resistivity analyses indicated that the Cu nanoparticles likely have oxidized surfaces while the Pd-containing films showed only minor chemical changes after annealing.

A method is presented for estimating the thickness of the monoclinic layer formed by hydrothermal degradation of zirconia doped with 3 mol% of yttria (3Y-TZP) by means of X-ray diffraction at different incidence angles. The method is based on: a) determining the monoclinic concentration in the degraded layer by X-ray diffraction at angles for which the beam penetration depth is smaller than the layer thickness; b) calculating and using the ratio between intensities of the same main tetragonal peak in the degraded and in the as sintered specimens at angles for which the contribution of the same tetragonal peak from the layer and from the underneath non-degraded material are significant. In order to compare with experimental results, 3Y-TZP has been subjected to degradation in an autoclave at temperatures of 131 °C in water vapour at a pressure of 0.2 MPa. The method may be useful when the thickness of the degraded layer is in the range between a few hundred nanometres and a few microns.

A method of quantitative estimation of microstructure homogeneity of mechanical alloyed composite materials is proposed. As an indicator of satisfactory degree of microstructure homogeneity a value of variation coefficient of 10% is accepted.

The kinetics of light-induced spin transition and relaxation in [Fe_xZn_1-x(phen)₂(NCS)₂] (phen=1,10-phenanthroline) has been investigated from time/temperature dependent x-ray powder diffraction with in situ optical excitation. We show that the phase transformation is driven by a heterogeneous nucleation and growth mechanism with phase separation, in both the thermally induced and light-induced regimes. The high spin to low spin isothermal relaxation curves strongly differ from first-order kinetics, and are interpreted using the Kolmogorov-Johnson-Mehl-Avrami model of phase transformation, from which the activation energy to domain growth is derived. Dilution tends to increase the activation energy, and slows down the whole relaxation process. Non-linear photo-induced kinetics as a function of laser power is evidenced, resulting from a light-induced phase separation process; a laser power threshold effect is pointed out. It is found that dilution speeds up the photo-conversion kinetics and reduces the laser power threshold.

The density of states of deep level centers in silicon oxynitride layer of SONOS memory cells are calculated from temperature dependent retention measurement. The dominating charge loss mechanisms are direct trap-to-band tunneling (TB) and thermally stimulated emission (TE). Retention measurements at low temperatures (80 – 300K) will be dominated by TE from more "shallow" traps with energies below 1eV and by TB. Taking into account both independent and rival processes the density of states could be calculated self consisting. The results are in excellent agreement with elsewhere published data.