Ori Yeheskel

• PhD
• Ben-Gurion University of the Negev

The first part of the talk is popular science that describe how 3D printing changes our life. The second part of the talk bring basic question a scientist has to ask porior to start of printing a new product.

Three types of Ti-6Al-4V alloys were prepared by powder bed fusion methods using a laser powder bed fusion (L-PBF) and two different electron-beam powder bed fusion (E-PBF) systems. The specific heat capacity, linear thermal expansion, and thermal diffusivity were measured from room temperature to ~ 1000 °C. The thermal conductivity values were cal...

Anelastic phenomena was studied at room temperature in Ti6Al4V produced by electron beam powder bed fusion (E-PBF). Samples were studied in the as-built and post-treated state and were compared with extruded and annealed material. Cyclic loading under tension-compression performed in the elastic regime (total strain of ±0.75%) revealed that the loo...

Additively-manufactured Ti-6Al-4V (Ti64) exhibits high strength but in some cases inferior elongation to those of conventionally manufactured materials. Post-processing of additively manufactured Ti64 components is investigated to modify the mechanical properties for specific applications while still utilizing the benefits of the additive manufactu...

This presentation shows relaxation in tension and compression in Ti64 in the as-built (AB) condition, after HIP at low temperature as compared to the extruded and annealed rod. In addition, experiments in tension-compression loops in the elastic regime are presented.

Electromechanically active ceramic materials, piezoelectrics and electrostrictors, provide the backbone of a variety of consumer technologies. Gd- and Sm-doped ceria are ion conducting ceramics, finding application in fuel cells, oxygen sensors, and, potentially, as memristor materials. While optimal design of ceria-based devices requires a thoroug...

The process of additive manufacturing (AM) has rapidly developed over the past two decades and is now addressing the needs of industry for fast production of samples with tailored properties and complex geometries. One of the most common alloys fabricated from powder using the Laser Powder Bed Fusion (L-PBF) method is AlSi10Mg. The effects of the i...

Dilatation measurements, combined with thermal programmed desorption mass spectrometry (TPD-MS), were utilized for studying thermally induced porosity (TIP) in selective laser melting additively manufactured (AM) AlSi10Mg and Ta30at.%–Ti samples produced by hot isostatic pressing (HIP). A clear abrupt upward deviation in thermal expansion is observ...

Using an electron beam melting (EBM) printing machine (Arcam A2X, Sweden), a matrix of 225 samples (15 rows and 15 columns) of Ti-6Al-4V was produced. The density of the specimens across the tray in the as-built condition was approximately 99.9% of the theoretical density of the alloy, ρ T. Tensile strength, tensile elongation, and fatigue life wer...

FIGURE 4 (A)-Density of undoped and Gd-doped ceria pellets relative to the theoretical lattice density, as a function of T 1 in the rapid sintering procedure (Figure 2A); (B)-The sintering temperature T opt1 yielding maximum pellet density (cf. Figure 4A) as a function of Gd-content.

Mechanical properties (tensile strength and creep) of AlSi10Mg specimens fabricated by selective laser melting (SLM) in the Z-direction were investigated in the 25–400 °C temperature range. Specimens were tested after stress relief treatment. The results revealed that yield stress (YS) significantly decreases and the elongation increases at tempera...

This study presents a detailed characterization of room temperature bulk microstructure and texture of additively manufactured Ti-6Al-4V alloy samples with the neutron time-of-flight diffractometer HIPPO. A comparison is made between samples that were manufactured by two different methods utilizing selective laser melting and electron beam melting....

Characterization of the bulk microstructure using neutron diffraction has been applied to investigate the phase fractions and textures of α- and β-phases in Ti-6Al-4V fabricated by additive manufacturing. The microstructure of a specimen cut from a fan structure, built by either electron beam melting (EBM) or selective laser melting, indicated that...

Pulse-echo ultrasonic method was carried out to investigate possible anisotropy in selective laser melting additively manufactured (AM) AlSi10Mg samples. Three types of ultrasonic analyses were employed: time of flight (TOF) sound velocity measurement, frequency depended attenuation and exponential fitted attenuation. Analysis of the transverse wav...

Pulse-echo ultrasonic method was carried out to investigate possible anisotropy in selective laser melting additively manufactured (AM) AlSi10Mg samples. Three types of ultrasonic analyses were employed: time of flight (TOF) sound velocity measurement, frequency depended attenuation and exponential fitted attenuation. Analysis of the transverse wav...

Thermally induced porosity (TIP) in additively manufactured (AM) AlSi10Mg alloy Einat Strumza1, Ori Yeheskel2 and Shmuel Hayun1 1Department of Materials Engineering Ben Gurion University of the Negev, P.O Box 653, Beer-Sheva 84105, Israel 2Department of Materials, NRCN, P.O.Box 9001, Beer-Sheva 84109, Israel The additive manufacturing process rapi...

Additive Manufacturing (AM) of Ti6Al4V alloy by Electron Beam Melting (EBM) yields unique microstructures characterized by micron and sub-micron grains. Phase content is primarily α-phase and residual β-phase. For the research of mechanical properties of AM Ti6Al4V, specimens in the as built (AB), heat treatment (HT), and hot isostatic pressing (HI...

Methodology for Maturity Evaluation Based on MRL and NDE for Powder Bed Fusion AM

Materials fabricated by AM technology requests in-depth investigation of a wide range of mechanical properties. In the present study mechanical properties (fatigue, tensile and creep) of an AM-SLM AlSi10Mg alloy were investigated. The results revealed that the as-built machined and polished specimens displayed the highest fatigue limit, stress reli...

We report on a rapid sintering protocol, which optimizes the preparation of 0‐29 mol% Gd‐doped ceria ceramics with density ≥ 98% of the theoretical crystal lattice value. The starting material is a nanometer grain‐sized powder prepared by carbonate co‐precipitation and calcined with minimal agglomeration and loss of surface area. Slow (5 °C/min) he...

The effect on fatigue resistance of additively manufactured (AM) AlSi10Mg specimens fabricated by selective laser melting (SLM) following surface treatment by shot-peening was investigated. Specimen surface was shot-peened with either steel or ceramic balls. Nano-indentation measurements revealed that shot-peening caused surface hardening, with the...

Powder Characteristics: Ti6 wt% Al4 wt% V powder was used. Particle size d 10 = 66 µm, d 50 = 84 µm and d 90 =120 µm. Background: Additive Manufacturing (AM) commonly called 3D printing. Metals are 3D printed using wire or powders, for the latter there are variety of methods including; selected laser melting (SLM), direct energy deposition (DED) an...

Outline Introduction Application of AM of metals Maturity (MRL and other approaches) Our methodology (Engineering and Scientific) DT, NDT and NDE  Ti6Al4V-EBM (strength, fatigue, NDT)

The introduction is a popular talk showing to what extent 3D printing entered the human life. Part of the talk shows our scientific approach and a new approach how to define 3D printing maturity.

The dissolution enthalpy, ΔHDS, and the formation enthalpy, ΔHf,ox, of bulk lutetium doped cerium oxide (LuDC) were studied at 701 °C in molten sodium molybdate. For the composition range of Ce1-XLuXO2-x/2, studied 0 ≤ X ≤ 0.3, the ΔHDS decreases linearly and smoothly with lutetium content according to ΔHDS,kJmol⁻¹=73.5(1.0)-165.1(5.5)·x). The enth...

3D printing of metals review and scientific approach and results on SLM Al10SiMg and EBM Ti6wt%Al4wt%V

10 mol% Gd-doped ceria (10GDC) ceramics, with grain size in the single micron range, display electrostrictive behavior under ambient conditions of temperature and pressure. In weak, quasi-static electric fields, i.e. <1 kV/cm, frequency <1 Hz, the longitudinal strain is measured to be proportional to the square of the applied electric field, albeit...

The fatigue resistance of AM-SLM AlSi10Mg samples built in the Z direction after various heat treatments was investigated. Specimens were tested in the as-built (AB) condition, after stress relief (SR) treatment and after SR and hot isostatic pressing (HIP) at either 250ºC or 500ºC. The AB machined and polished specimens displayed the highest fatig...

The Young's, shear and bulk moduli of dense (> 95%) Gd-doped ceria (Ce1 - xGdxO2 - x/2) ceramics were determined as a function of Gd content using the ultrasonic pulse-echo method and corrected for porosity according to both static and dynamic models. With increasing defect concentration (0–20 mol% Gd), the Young's and shear moduli decrease linearl...

Classical electrostriction, describing a second-order electromechanical response of insulating solids, scales with elastic compliance, S, and inversely with dielectric susceptibility, ε. This behavior, first noted 20 years ago by Robert Newnham, is shown to apply to a wide range of electrostrictors including polymers, glasses, crystalline linear di...

Neutron diffraction study of poly-crystalline bulk samples of Ti-6Al-4V, prepared using laser selective melting (SLM) and electron beam melting (EBM), and of their ingredient powders, is reported. Both the SLM and EBM samples do not contain the macro- and micro-strain, found in the ingredient powder particles. In addition, the micro-structure of th...

Herein careful analysis of in situ neutron diffraction patterns obtained, while cyclically loading highly tex-tured polycrystalline Ti 2 AlC, a MAX phase, samples, provides compelling experimental evidence – in the form of fully reversible peak lattice elastic strain loops and peak widening and narrowing upon load cycling – for the existence of ful...

Steel can containing TiAl sample after HIP, alongside a machined TiAl sample

Sintering of nanocrystalline (nc) monoclinic yttrium oxide (Y 2 O 3) was studied in the homologue temperature range of 0.4–0.7T M . Samples were isostatically consolidated at super high pressure (SHP), up to 1.8 GPa. The combined effects of consolidation pressure and sintering temperature on the properties and microstructure are explored. The physi...

The Young's moduli, E, and nanoindentation, NI, stress–strain curves of fine-grained scandia, Sc2O3, and erbia, Er2O3, were determined using spherical indenters with radii of 1.4μm and 5μm. The Young's moduli measured with the spherical indenters, were comparable to those measured by a Berkovich tip, and by ultrasound. This work further validates t...

The hydrogen absorption ability of the non-absorbing Al-rich ZrAl2 compound was examined after reducing its particles-size to the nanometer regime. The hydrogen abstinence of bulk ZrAl2 has been previously related to its excessive elastic shear stiffening. The particle size of ZrAl2 was reduced by attrition milling and cryomilling. The minimal aver...

In this paper we report in situ neutron diffraction results of fine-grained (8 μm) polycrystalline titanium sulfocarbide samples loaded to 700 MPa. The overall strains, and those on individual planes, are modeled via the elastoplastic self-consistent approach using elastic constants derived from ab initio calculations. Based on the results, we conc...

The bulk modulus of scandia is evaluated by ab initio calculation, based on density functional theory, and compared with bulk modulus measurement on nearly fully dense scandia and with the value attained from the equation of state based on diamond anvil cell measurements. The current results are in the upper range of the bulk moduli results in the...

The Young's moduli, E, and nanoindentation, NI, stress–strain curves of fine-grained scandia, Sc 2 O 3 , and erbia, Er 2 O 3 , were determined using spherical indenters with radii of 1.4 m and 5 m. The Young's moduli measured with the spherical indenters, were comparable to those measured by a Berkovich tip, and by ultrasound. This work further val...

An examination of the elastic moduli of a number of the polycrystalline intermetallic compounds LaMxNi5�x (M¼Al,Sn) reveals a simple relation between the shear modulus, G, and Young’s modulus, E. The results, for a wide range of x, show that the ratio G=E is approximately constant. Further, this constant for these hexagonal close packed (hcp) struc...

Herein we show that the stress-induced, dislocation-based, elastic hysteric loops of kinking nonlinear elastic solids---polycrystalline cobalt, 10vol% porous Ti2AlC , and fully dense Ti3SiC2 ---obey the scalar Preisach-Mayergoyz phenomenological model because they exhibit wiping out and congruency, two necessary and sufficient tenets of the model....

Lanthanide sesquioxides (Ln2O3) display three stable solid phases as a function of temperature. It has been assumed that Y2O3 should display similar crystal structures and phase transitions as other Ln2O3. Recently a new phase transition sequence was reported for Y2O3, contradicting earlier studies. In this work Y2O3 was found to have the same phas...

Recently cobalt was classified as a kinking nonlinear elastic, KNE, solid. Fully reversible incipient kink bands, IKBs, were invoked to explain both its microyielding and hysteretic stress–strain curves. Hereinwe present further evidence and insights in the KNE nature of cobalt by measuring its mechanical hysteresis as a function of grain size, pre...

The Young's modulus (E) and nanoindentation (NI) stress–strain curves of fully dense, transparent yttria were determined using a nano-indenter capable of continually measuring the stiffness (S). Two hemispherical indenters with radii of 1.4 and 5 μm were used, in addition to a Berkovich tip. The E values—calculated from the S vs. a (contact radius)...

The crystallographic structure of HfIr3 was studied as a function of pressure using X-ray diffraction technique. No phase transition was observed up to a pressure of 27.6 GPa, with a total volume contraction of V/V0 ≅ 0.92. The bulk modulus value, calculated from the X-ray experimental data and from the sound-velocity technique, are B=279±4 and 297...

The present study shows the effect of porosity on the dynamic elastic moduli of partially dense yttria (Y2O3). This article reveals that the sound velocities and the elastic moduli of the porous samples depend not only on density, but also upon the reciprocal of the initial particle and agglomerate size. These findings explain some of the variation...

Herein we report on direct experimental observation of nonlinear hysteretic ultrasonic wave transmission through the kinking nonlinear elastic solids Ti3SiC2 and Ti3AlC2 under bias-stress loading. We observed two characteristic regimes; up to strain �2�10−4, the ultrasound attenuation increased strongly and linearly with strain. At higher strains,...

The increase in sound velocities during the aging of M250 maraging steel reported by Rajkumar et al. was analyzed. The present article provides a new perspective on why and to what extent the sound velocities change during aging. The main parameter that affects the elastic moduli and the sound velocities in the early and intermediate stages of agin...

Using bulk acoustic waves we studied the nonlinear mechanical properties and hysteresis of the acousto-elastic effect in kinking nonlinear elastic, KNE, solids. The experiments reviewed here present direct observation of nonlinear hysteretic scattering and attenuation of ultrasonic waves in Ti3SiC2 and Ti3AlC2, representatives of KNE solids, as a f...

Interfacial chemistry of mullite fiber reinforced-mullite matrix composites was examined using SEM/EDX and scanning AES. All the fibers bond strongly to the matrix and exhibit no sliding during a fiber push-in test. Excess Si over Al is found at the fiber-matrix interfaces. AES results show the carbon layer is nonuniform and in some cases less than...

Thermoelectric power (TEP) measurements had been proved as an effective method for evaluating the metallurgical state of various alloys. The current work was conducted in order to evaluate the influence of the aging state of Maraging 250 steel on TEP values. Commercial Maraging 250 steel was aged at 500 °C for 0.5-6 hours (hrs). TEP, hardness (Rc)...

The elastic moduli of γ‐TiA1 were studied in porous samples consolidated by various techniques e.g. cold isostatic pressing (CIP), pressure‐less sintering, or hot isostatic pressing (HIP). Porosity linearly affects the dynamic elastic moduli of samples. The results indicate that the sound wave velocities and the elastic moduli affected by the proce...

The authors report on a pronounced increase in the elastic shear modulus of a wide class of binary intermetallics upon pseudobinary substitution. They further claim that the aforementioned increase in the rigidity of these compounds is the mechanism underlying the well documented, sharp decline of hydrogen absorption in these compounds. They sugges...

Dense MgO ceramics with nanometer to submicrometer grain size were fabricated by high-temperature hot-isostatic pressing, low-temperature hot-pressing, and spark plasma sintering. The elastic properties were determined by sound wave velocity measurements. Young's and shear moduli of nanocrystalline MgO were lower by 13% than those with submicromete...

The elastic moduli of yttria (Y2O3) samples that were made from powders with various particle morphologies were studied by means of ultrasonic measurements. The soundwave velocities in the longitudinal and transverse modes were measured. The elastic moduli were calculated from the sound velocities and density. For the high-purity, high-density (>50...

The elastic moduli of the polycrystalline intermetallic compounds LaAl x Ni 5−x (x = 0, 0.25, 0.50 and 1.00) have been measured over the temperature range 3–415 K and those of LaSn x Ni 5−x (x = 0.10, 0.22, 0.40 and 0.50) over the temperature range 65–400 K. The samples were prepared by a hot isostatic pressing technique and had near theoretical de...

Ultrasonic methods were used to measure the room-temperature elastic moduli of polycrystalline LaSnxNi5−x compounds for 0⩽x⩽0.5. These materials are of great importance for their hydrogen storage properties. The samples, prepared by a hot isostatic pressing method, had near-theoretical densities with calculated porosities ranging from 0 to 1.5%. Th...

The effect of cold compaction and sintering of spherical iron powder on the dynamic elastic moduli of the partially densified material was studied. It was found that the elastic moduli of porous iron depend not only on density but also on the processing route that is followed. It was argued and demonstrated that the longitudinal sound velocity is m...

The effect of porosity on the dynamic elastic moduli of -TiAl samples that had been consolidated by cold isostatic pressing (CIP), pressureless sintering and hot isostatic pressing (HIP) was studied by ultrasonic sound velocity measurements. The results indicate that the sound wave velocities and the elastic moduli are affected by the processing r...

The elastic moduli of porous copper in the cold pressed and in the sintered states were studied using the ultrasonic method. At equal density level, the elastic moduli of the sintered material are higher than those of cold compacted samples. A sharp increase of the elastic moduli associated with only a minute increase of density is observed at the...

The effect of porosity on the dynamic elastic moduli of γ titanium aluminides samples that had undergone pressureless sintering or hot isostatic compaction was studied by ultrasonic sound wave velocity (SWV) measurements. The results indicate that the processing route affects the SWV and the elastic moduli. The latter depend not only on the density...

A new assessment method for some elastic moduli of porous ceramics was recently proposed. This method is based on the determination of a correlation between the Young's and the shear moduli, of a given porous material. Using such a correlation enables one to use a single sound wave velocity for quantitative non-destructive evaluation (QNDE) of all...

A hot isostatic pressing technique was used to prepare bulk polycrystalline samples of the hydrogen-absorbing materials LaAl _x Ni _5-x. Ultrasonic methods were used to measure the elastic moduli of these alloys. Small corrections were made for porosity so that values expected for the theoretical density were found. The various...

Acid assisted consolidation (AAC) is a technique that provides elevatedlevels of cohesiveness to silver powder compacts without recourse to a high temperature treatment. Ultrasonic techniques were used to measure the elastic constants of high purity silver compacts as a function of several processing variables. The elastic moduli of untreated (NT)...

A new assessment method for the elastic moduli of porous materials is proposed. This method is based on a linear cor-relation between the Young's and the shear moduli of a given porous material. It is shown that such a correlation prevails for ce-ramics (Al 2 O 3 , ThO 2 , and ZnO) and for glass (SiO 2) having Pois-son's ratios of the solid bulk in...

Diffusion bonding is a process in which both elevated temperature and pressure are applied to the interface between two samples until a permanent bond is established1, 2. Diffusion bonding techniques are frequently used in applications where the high heat input of welding has to be avoided. Since the time required for the formation of a good bond d...

The hot isostatic pressing (HIP) of Si3N4 was performed in the temperature range 1500–1800°C and within the pressure range 90–172 MPa. Both additive-free Si3N4 and Si3N4 with Y2O3 additions were studied. During the HIP process the transformation of α-Si3N4toβ-Si3N4 occurs and the amount of α→β transformation increases as the HIP temperature and HIP...

The hot isostatic pressing (HIP) of Si3N4 was performed in the temperature range 1500-1800 °C and within the pressure range 90-1 72 MPa. Both additive-free Si3N 4 and Si3N 4 with Y203 additions were studied. During the HIP process the transformation of (~-SisN 4 to ~3-Si3N 4 occurs and the amount of (~ -+ ~3 transformation increases as the HIP temp...

It is suggested that the elastic moduli MSi3N4 of Si3N4 are a linear combination of the α- and βSi3N4 contents multiplied by their elastic moduli MSi3N4 = Cα/(α+β)Mα + Cβ/(α+β)Mβ The elastic moduli of fully dense α- and βSi3N4 are evaluated. The elastic moduli of αSi3N4 are Eα = 362 GPa, Gα = 144 GPa and να = 0.25, and those of βSi3N4 are Eβ =...

The effect of Y2O3 additive on the properties of hot isostatically pressed silicon nitride was studied. The influence of small additions of Y2O3 on the densification of silicon nitride was investigated. The density and elastic moduli of the product increase with increasing of the Y2O3 additions. The hot isostatically pressed pure silicon nitride co...

The present work manifests the results of the dynamic Young's modulus, E, after cold compaction and after sintering of partially dense copper and silver compacts. For both metals, the results show that E in the porous compacts depends not only on the attained density, but also on the samples' consolidation route. For porous metals, it is demonstrat...

Nickel aluminide intermetallic compounds, mainly NiAl and Ni 3 Al, have been considered as promising high-temperature structural materials because of their high melting points, low densities and good oxidation resistance. Ni-Al intermetallics are potential candidates as heat shields in chambers and gas turbines, however, these materials suffer from...