High Energy Materials Science Beamline Research Articles

Graded Inconel-stainless steel multi-material structure by inter- and intralayer variation of metal alloys

Additively manufactured multi-metal hybrid structures can be designed as functionally graded materials providing an optimized response at specific positions for particular applications. In this study, liquid dispersed metal powder bed fusion is used to synthesize a multi-metal structure based on Inconel 625 (IN625) and stainless steel 316L (S316L) stainless steel regions, built on a S316L base plate. Both alloys alternate several times along the build direction as well as within the individual sublayers. The multi-metal sample was investigated by optical microscopy, scanning electron microscopy, microhardness measurements, nanoindentation and energy-dispersive X-ray spectroscopy. Cross-sectional synchrotron X-ray micro-diffraction 2D mapping was carried out at the high-energy material science beamline of the storage ring PETRAIII in Hamburg. Sharp morphological S316L-to-IN625 interfaces along the sample's build direction are observed on the micro- and nanoscale. A gradual phase transition encompassing about 1 mm is revealed in the transverse direction. Mechanical properties change gradually following abrupt or smooth phase transitions between the alloys where a higher strength is determined for the superalloy. The two-dimensional distribution of phases can be assessed indirectly as S316L and IN625 in this multi-metal sample possess a <110> and a <100> fiber crystallographic texture, respectively. Tensile residual stresses of ∼900 and ∼800 MPa in build direction and perpendicular to it, respectively, are evaluated from measured residual X-ray elastic strains. Generally, the study indicates possibilities and limitations of liquid dispersed metal powder bed fusion for additive manufacturing of functionally graded materials with unique synergetic properties and contributes to the understanding of optimization of structurally and functionally advanced composites.

In-situ analysis of the elastic-plastic characteristics of high strength dual-phase steel

Modeling the elastic behavior of dual-phase steels is complex due to the strain dependency of Young's modulus and high elastic nonlinearity. Since it is assumed that reasons for this are to be found in microstructural behavior, microscopic in-situ analysis are necessary, but due to the overlap of the martensite and ferrite peaks, the evaluation of diffraction profiles is highly complex. Within this work, CR590Y980T (DP1000) is investigated in a continuous cyclic tensile and tension-compression test under synchrotron radiation at High Energy Material Science beamline P07 in Petra III, DESY. On basis of additional EBSD measurements, an evaluation approach is shown to analyze the dual-phase diffraction profiles in such a way that martensite and ferrite can be separated for three lattice planes. The origin of the specific elastic-plastic behavior of dual-phase steels in terms of onset of yielding, anelasticity or early re-yielding is analyzed on the basis of lattice strains and interphase stresses. For this, the time-synchronously measured micro data is correlated with the macro stress-strain relationship and thermoelastic effect. The results help to better understand strain-dependent elastic-plastic behavior of DP steels on a micro level and provide great potential to improve characterization and modeling in terms of springback prediction.

In-situ analysis of the thermoelastic effect and its relation to the onset of yielding of low carbon steel

The thermoelastic effect indicates the dependency of temperature and volume change in the material and, due to the heat released during plastic deformation, a temperature minimum occurs in the region of the onset of yielding. An experimental setup is presented for the microscopic analysis of the thermoelastic effect, which allows high precision measurements of specimen. In-situ diffraction experiments were performed for a single phase low carbon steel HC260Y using synchrotron diffraction at the High Energy Material Science beamline P07 in Petra III, DESY. This allows a direct comparison of the onset of yielding by observing the evolution of lattice strains and dislocations densities with the specimen temperature in a continuous cyclic test having high measuring frequency and accuracy. Therefore, the lattice strains are evaluated based on the peak shift of several lattice planes and the dislocation density is estimated based on the micro strain due to peak broadening. The results prove existing assumptions about the relation between the thermoelastic effect and the onset of yielding and clearly qualify the temperature-based determination method for material characterization on a microstructural basis. The usefulness of the temperature elasticity parameters is shown exemplarily with the determination of loading moduli and compared to existing methods.

In Situ Synchrotron X‐Ray Diffraction during High‐Pressure Torsion Deformation of Ni and NiTi

A down‐sized high‐pressure torsion device is developed to be used in an INSTRON deformation machine available at the High Energy Materials Science beamline at PETRA III. This setup allows to obtain synchrotron diffraction patterns in situ during severe plastic straining. Two different materials are studied: in pure Ni, the dislocation density and coherently scattering domain size are analyzed; in NiTi shape memory alloy, amorphization and a reverse martensitic phase transformation are investigated. The in situ experiments facilitate the characterization of the microstructural evolution of these materials depending on uniaxial loading, hydrostatic pressure, and torsional strain.

A zone melting device for the in situ observation of directional solidification using high-energy synchrotron x rays.

Directional solidification (DS) is an established manufacturing process to produce high-performance components from metallic materials with optimized properties. Materials for demanding high-temperature applications, for instance in the energy generation and aircraft engine technology, can only be successfully produced using methods such as directional solidification. It has been applied on an industrial scale for a considerable amount of time, but advancing this method beyond the current applications is still challenging and almost exclusively limited to post-process characterization of the developed microstructures. For a knowledge-based advancement and a contribution to material innovation, in situ studies of the DS process are crucial using realistic sample sizes to ensure scalability of the results to industrial sizes. Therefore, a specially designed Flexible Directional Solidification (FlexiDS) device was developed for use at the P07 High Energy Materials Science beamline at PETRA III (Deutsches Elektronen-Synchrotron, Hamburg, Germany). In general, the process conditions of the crucible-free, inductively heated FlexiDS device can be varied from 6 mm/h to 12 000 mm/h (vertical withdrawal rate) and from 0 rpm to 35 rpm (axial sample rotation). Moreover, different atmospheres such as Ar, N2, and vacuum can be used during operation. The device is designed for maximum operation temperatures of 2200 °C. This unique device allows in situ examination of the directional solidification process and subsequent solid-state reactions by x-ray diffraction in the transmission mode. Within this project, different structural intermetallic alloys with liquidus temperatures up to 2000 °C were studied in terms of liquid-solid regions, transformations, and decompositions, with varying process conditions.

Determination of Temperature-Dependent Elastic Constants of Steel AISI 4140 by Use of In Situ X-ray Dilatometry Experiments.

In situ dilatometry experiments using high energy synchrotron X-ray diffraction in transmission mode were carried out at the high energy material science beamline P07@PETRAIII at DESY (Deutsches Elektronen Synchrotron) for the tempering steel AISI 4140 at defined mechanical loading. The focus of this study was on the initial tempering state () and the hardened state (). Lattice strains were calculated from the 2D diffraction data for different planes and from those temperature-dependent lattice plane specific diffraction elastic constants () were determined. The resulting coupling terms allow for precise stress analysis for typical hypoeutectoid steels using diffraction data during heat treatment processes, that is, for in situ diffraction studies during thermal exposure. In addition, by averaging specific and macroscopic temperature-dependent elastic constants were determined. In conclusion a novel approach for the determination of phase-specific temperature-dependent DECs was suggested using diffraction based dilatometry that provides more reliable data in comparison to conventional experimental procedures. Moreover, the averaging of lattice plane specific results from in situ diffraction analysis supply robust temperature-dependent macroscopic elastic constants for martensite and ferrite as input data for heat treatment process simulations.

A custom built lathe designed for in operando high-energy x-ray studies at industrially relevant cutting parameters

We present a custom built lathe designed for in operando high-energy x-ray scattering studies of the tool-chip and tool-workpiece contact zones during operation. The lathe operates at industrially relevant cutting parameters, i.e., at cutting speeds ≤400 m/min and feeds ≤0.3 mm/rev. By turning tests in carbon steel, performed at the high-energy material science beamline P07 at Petra III, DESY, Hamburg, we observe compressive strains in TiNbAlN and Al2O3/Ti(C, N) coatings on the tool flank face during machining. It is demonstrated that by the right choice of substrate and coating materials, diffraction patterns can be recorded and evaluated in operando, both from the tool-workpiece and tool-chip contacts, i.e., from the contact zones between the tool and the workpiece material on the tool flank and rake faces, respectively. We also observe that a worn tool results in higher temperature in the tool-chip contact zone compared to a new tool.

Follow-up structural evolution of Ni/Ti reactive nano and microlayers during diffusion bonding of NiTi to Ti6Al4V in a synchrotron beamline

Reaction-Assisted Diffusion Bonding (RADB) of NiTi to Ti6Al4V using either magnetron sputtered Ni/Ti nanomultilayers or Ni/Ti commercial microfoils as filler material was studied. The joining process takes advantage of the exothermal reactive character of the Ni-Ti system to provide extra energy during the bonding process. Therefore, sound joints could be achieved at lower thermal conditions. The oven with load capabilities at the High Energy Materials Science beamline (P07) of the Deutsch Synchrotron (DESY) is ideal to follow the structural evolution of the materials involved in the bonding process. Prior to RABD, Ni/Ti multilayers with a 2.5 μm total thickness and with 12 or 25 nm of modulation period were deposited onto the materials being joined. In alternative, up to 20 alternated thin μ-foils were placed in between the base materials. The materials were heated by induction to the selected temperature during 30 min and quenched to room temperature by blowing helium. During the thermal cycle a 10 MPa pressure was applied. Using thin μ-foils, 650 °C was required to promote joining, while using multilayer coated materials sound joints were obtained at 600 °C. Such low temperatures are attractive from the application/economic point of view, and are crucial to reduce the formation of undesired intermetallic phases, such as NiTi2. The nanoindentation experiments of the joints processed using Ni/Ti nanomultilayers confirm that the presence of the NiTi2 phase is more pronounced at 650 °C than when the joints are processed at 600 °C.

In Situ Experiment for Laser Beam Welding of Ti Alloys Using High-Energy X-Rays

The laser beam welding (LBW) process has many advantages for industrial production; however, it still has to be optimized for two-phase Ti alloys. Phase transformations and residual stresses play a crucial role for welding these alloys. Specific questions about the development of phase content during fast heating with a laser and rapid cooling can only be addressed with time-resolved in-situ experiments, avoiding artefacts from quenching. Also the residual stress development during cooling depends on the occurring phase transformations. Thus, an LBW chamber employing a fibre laser was developed for use with high-energy X-rays from a synchrotron source. Bead-on-plate welding experiments with 2.5 mm thick samples were carried out at the HZG high-energy materials science beamline (HEMS) at DESY, Hamburg. The first experiments focused on the solid-solid phase transformations in a Ti-6Al-4V alloy. Moreover, residual stresses developing during cooling were studied.

Dislocation density evolution of AA 7020-T6 investigated by in-situ synchrotron diffraction under tensile load

The dislocation density evolution along the loading axis of a textured AA 7020-T6 aluminum alloy during uniaxial tension was investigated by in-situ synchrotron diffraction. The highly parallel synchrotron beam at the High Energy Materials Science beamline P07 in PETRA III, DESY, offers excellent conditions to separate different influences for line broadening from which micro-strains are obtained using the modified Williamson–Hall method which is also for defect density investigations. During tensile loading the dislocation density evolution was documented from the as-received material (initial micro-strain state) to the relaxation of the strains during elastic deformation. After yield, the increasing rate of dislocation density growth was relatively fast till half-way between yield and UTS. After that, the rate started to decrease and the dislocation density fluctuated as the elongation increased due to the generation and annihilation of dislocations. When dislocation generation is dominant, the correlation between the flow stress and dislocation density satisfies the Taylor equation. Besides, a method to correct the thickness effect on peak broadening is developed in the present study.

Industry-relevant magnetron sputtering and cathodic arc ultra-high vacuum deposition system for in situ x-ray diffraction studies of thin film growth using high energy synchrotron radiation.

We present an industry-relevant, large-scale, ultra-high vacuum (UHV) magnetron sputtering and cathodic arc deposition system purposefully designed for time-resolved in situ thin film deposition/annealing studies using high-energy (>50 keV), high photon flux (>10(12) ph/s) synchrotron radiation. The high photon flux, combined with a fast-acquisition-time (<1 s) two-dimensional (2D) detector, permits time-resolved in situ structural analysis of thin film formation processes. The high-energy synchrotron-radiation based x-rays result in small scattering angles (<11°), allowing large areas of reciprocal space to be imaged with a 2D detector. The system has been designed for use on the 1-tonne, ultra-high load, high-resolution hexapod at the P07 High Energy Materials Science beamline at PETRA III at the Deutsches Elektronen-Synchrotron in Hamburg, Germany. The deposition system includes standard features of a typical UHV deposition system plus a range of special features suited for synchrotron radiation studies and industry-relevant processes. We openly encourage the materials research community to contact us for collaborative opportunities using this unique and versatile scientific instrument.

Locally resolved stress and strain analysis of sinter-joined micro valves using synchrotron X-ray diffraction and conical slit apertures

For assessing the quality of the joining area as well as researching the influence of joining parameters in combination with different materials, the principal stress components of sinter-joined micro valves were analysed. Transmission experiments have been conducted at the high-energy material science (HEMS) beamline P07 at PETRA III, DESY. Due to the dimensions of the samples, a high spatial resolution of the measurements was required. Of special interest was the distribution of residual stress in the joining area of the valves, which demanded a depth resolved measurement using a conical slit. Strains were deduced from the obtained Debye---Scherrer rings of the {200}, {211}, and {220}-planes of the ?/??-phase involving reference measurements on non-sintered powder of the specimen materials. The grain statistics have been improved by integrating over slices of the diffraction rings and by calculating a mean lattice parameter taking into account all lattice planes. From the strain data, the hydrostatic and the deviatoric stress were calculated for the three dimensional stress state.

High energy X-ray diffraction study of a dental ceramics–titanium functional gradient material prepared by field assisted sintering technique

A functional gradient material with eleven layers composed of a dental ceramics and titanium was successfully consolidated using field assisted sintering technique in a two-step sintering process. High energy X-ray diffraction studies on the gradient were performed at High Energy Material Science beamline at Desy in Hamburg. Phase composition, crystal unit edges and lattice mismatch along the gradient were determined applying Rietveld refinement procedure. Phase analysis revealed that the main crystalline phase present in the gradient is α-Ti. Crystallinity increases stepwisely along the gradient with a decreasing increment between every next layer, following rather the weight fraction of titanium. The crystal unit edge a of titanium remains approximately constant with a value of 2.9686(1)Å, while c is reduced with increasing amount of titanium. In the layer with pure titanium the crystal unit edge c is constant with a value of 4.7174(2)Å. The lattice mismatch leading to an internal stress was calculated over the whole gradient. It was found that the maximal internal stress in titanium embedded in the studied gradient is significantly smaller than its yield strength, which implies that the structure of titanium along the whole gradient is mechanically stable.

In Situ Characterization of NiTi/Ti6Al4V Joints During Reaction-Assisted Diffusion Bonding Using Ni/Ti Multilayers

Reaction-assisted diffusion bonding process of NiTi and Ti6Al4V was studied in situ. For this purpose, experiments were carried out at the High Energy Materials Science beamline (P-07) at PETRA-III (DESY). Ni/Ti multilayer thin films 2.5 μm thick with 12 and 25 nm modulation periods were directly deposited by magnetron sputtering onto the materials being joined. The NiTi and Ti6Al4V coated parts were placed with the films facing each other in a dilatometer equipped with Kapton windows for the x-ray beams. Microjoining was promoted by applying a 10 MPa pressure and inductively heating the materials, while simultaneously acquiring x-ray diffraction scans across the bond interface. Sound joints were produced at 750 °C. The formation of the NiTi2 phase could not be avoided.

The High Energy Materials Science Beamline (HEMS) at PETRA III

The HEMS beamline at PETRA III has a main energy of 120 keV, is tunable in the range 30-200 keV, and optimized for sub-micrometer focusing with Compound Refractive Lenses. Design, construction, and main funding was the responsibility of the Helmholtz-Zentrum Geesthacht, HZG. Approximately 70 % of the beamtime is dedicated to Materials Research, the rest reserved for “general physics” experiments covered by DESY, Hamburg. The beamline P07 in sector 5 consists of an undulator source optimized for high energies, a white beam optics hutch, an in-house test facility and three independent experimental hutches, plus additional set-up and storage space for long-term experiments. HEMS has partly been operational since summer 2010. First experiments are introduced coming from (a) fundamental research for the investigation of the relation between macroscopic and micro-structural properties of polycrystalline materials, grain-grain-interactions, recrystallisation processes, and the development of new &amp; smart materials or processes; (b) applied research for manufacturing process optimization benefitting from the high flux in combination with ultra-fast detector systems allowing complex and highly dynamic in-situ studies of microstructural transformations, e.g. in-situ friction stir welding; (c) experiments targeting the industrial user community.

Depth-Resolved Residual Stress Analysis with Conical Slits for High-Energy X-Rays

A conical slit cell for depth-resolved diffraction of high-energy X-rays was tested at the high-energy materials science beamline HEMS at PETRA III and used for the analysis of residual stresses in a laser beam welded steel overlap joint. With a conical slit width of 20 µm and beam cross-sections below 100 µm, depth resolutions well below 1 mm were achieved. The residual stress distributions obtained from the steel joint were in very good agreement with previous results from neutron diffraction measurements, although they were still noisier because of inferior grain statistics.

Grain Tracking at the High Energy Materials Science Beamline of the Petra III Synchrotron Radiation Source

Grain tracking is a term used to describe experiments that investigate polycrystalline materials in terms of the crystallites or grains from which they are composed, non-destructively and in three dimensions. The new German high brilliance synchrotron radiation source, Petra III, will become available to users in 2010 [1]. The GKSS research centre will operate two beamlines, including the high energy materials science beamline (HEMS) [2]. HEMS will feature an instrument dedicated to grain tracking, able to support a range of experiments of this kind. This paper describes the design and specification of this instrument, and gives examples of the types of experiments that will be possible.

The New GKSS Materials Science Beamlines at DESY: Recent Results and Future Options

GKSS is currently investing heavily into new beamlines at DESY in Hamburg, Germany. After the completed installation of the wiggler beamline HARWI II at DORIS III GKSS is now building two new undulator beamlines at the new PETRA III storage ring. The High Energy Materials Science Beamline (HEMS) will allow high resolution diffraction experiments using samples and sample environments with masses up to 1 t, 3DXRD measurements, and high-energy micro-tomography experiments. The Imaging Beamline (IBL) will provide a nano-tomography as well as a micro-tomography station for X-ray energies up to 50 keV. Examples of typical experiments in the field of residual stress analysis, micro-tomography, and high-energy small-angle X-ray scattering will be given.

S61 The New High Energy Materials Science Beamline (HEMS) at PETRA III

S61 The New High Energy Materials Science Beamline (HEMS) at PETRA III

The High Energy Materials Science Beamline at PETRA III

The future High Energy Materials Science Beamline HEMS at the new German high brilliance synchrotron radiation storage ring PETRA III [1] will have a main energy of 120 keV, will be fully tunable in the range of 50 to 300 keV, and will be optimized for sub-micrometer focusing with Compound Refractive Lenses and Kirkpatrick-Baez Multilayer mirrors. Design and construction is the responsibility of the Research Center Geesthacht, GKSS, with approximately 70 % of the beamtime being dedicated to Materials Research, the rest reserved for “general physics” experiments covered by DESY, Hamburg. Fundamental research will encompass metallurgy, physics and chemistry. For first experiments in investigating grain-grain-interactions a dedicated 3D-microstructure-mapper will be designed. Applied research for manufacturing process optimization will benefit from the high flux in combination with ultra-fast detector systems allowing complex and highly dynamic in-situ studies of microstructural transformations. The beamline infrastructure will allow easy accommodation of large user provided equipment. Experiments targeting the industrial user community will be based on well established techniques with standardised evaluation, allowing "full service" measurements. Environments for strain mapping [2] on large structural components up to 1 t will be provided as well as automated investigations of large numbers of samples, e.g. for tomography and texture determination. The current design for the beamline (P07 in sector 5 of the future experimental hall) consists of a nearly five meter in-vacuum undulator source (U19-5) optimized for high energies, a general optics hutch, an in-house test facility and three independent experimental hutches working alternately, plus additional set-up and storage space for long-term experiments. HEMS should be operational in spring 2009 as one of the first beamlines running at PETRA III.