Furnace Annealed Samples Research Articles

High Temperature Tensile Strength of TI6AL4V Processed by L-PBF—Influence of Microstructure and Heat Treatment

Ti6Al4V is the most widely used α‑β Titanium alloy for application in medicine, automotive, and aerospace, known for its high strength and corrosion resistance, but also its high maximal operating temperature of around 420 °C. Combined with its decent weldability under a shield atmosphere it has become a standard alloy for additive manufacturing processes, especially laser and electron beam powder bed fusion (L-PBF). Although this material is well studied, the influence of the L‑PBF process on its tensile properties at elevated temperatures remains almost unexplored. For that reason, this contribution focuses on the analysis of the tensile properties of Ti6Al4V up to 500 °C for different heat treatments and compares it to aerospace standards.Furnace annealed samples reach a tensile strength between 1022 to 660 MPa from room temperature to 500 °C respectively, while stress-relieved specimens reach 1205 to 756 MPa. Stress-relieved samples show a lower ductility at room temperature, but elongation at break increases at high temperature and outperforms furnace annealed samples at 500 °C.

The influence of surface on direction of diffusion in Al-Fe clad material

Aluminium-steel clad composite was manufactured by twin-roll casting. An intermetallic layer of Al 5 Fe 2 and Al 13 Fe 4 formed at the interface upon annealing above 500 °C. During in-situ annealing in transmission electron microscope, the layer grew towards the steel side of the interface in tongue-like protrusions. A study of furnace-annealed samples revealed, that the bulk growth of the interface phase proceeds towards the aluminium side. The growth towards steel is a surface effect that takes place simultaneously with the bulk growth towards aluminium. At the beginning of the intermetallic layer formation diffusion of Fe into aluminium prevails, afterwards Al atoms diffuse throught the newly formed intermetallic layer towards steel and the whole interface shifts towards aluminium. The kinetics of growth of the intermetallic layer follows parabolic law in both cases, indicating that the growth is governed by diffusion. • In Al-steel clad material intermetallic layer grows towards Al in bulk material. • During in-situ heating in TEM layer grows towards steel. • Steel-facing layer is a surface phenomenon. • Growth of the intermetallic layer follows parabolic law.

Effect of thermal annealing on the optical and structural properties of (311)B and (001) GaAsBi/GaAs single quantum wells grown by MBE

The effect of Furnace Annealing (FA) and Rapid Thermal annealing (RTA) on the structural and optical properties of GaAs1 − xBix/GaAs single quantum wells grown on (001) and (311)B substrates by molecular beam epitaxy was investigated. The structural properties were investigated by high-resolution x-ray diffraction (HR-XRD) and Transmission Electron Microscopy. The Bi concentration profiles were determined by simulating the HR-XRD 2θ−ω scans using dynamical scattering theory to estimate the Bi content, lattice coherence, and quality of the interfaces. The Bi composition was found to be similar for both samples grown on (001) and (311)B GaAs substrates. However, the simulations indicate that the Bi composition is not only limited in the GaAsBi quantum well (QW) layer but also extends out of the GaAsBi QW toward the GaAs barrier. Photoluminescence (PL) measurements were performed as a function of temperature and laser power for samples with a nominal Bi composition of 3%. PL spectra showed that (001) and (311)B samples have different peak energies at 1.23 eV and 1.26 eV, respectively, at 10 K. After RTA at 300 °C for 2 min, the PL intensity of (311)B and (001) samples was enhanced by factors of ∼2.5 and 1.75, respectively. However, for the (001) and (311)B FA samples, an enhancement of the PL intensity by a factor of only 1.5 times could be achieved. The enhancement of PL intensity in annealed samples was interpreted in terms of PL activation energies, with a reduction in the alloy disorder and an increase in the Bi cluster.

Impact of thermal-induced sapphire substrate erosion on material and photodetector characteristics of sputtered Ga2O3 films

Monoclinic β–phase gallium oxide (β-Ga2O3) films were deposited on c-plane sapphire substrates using a combination of sputtering and post annealing processes. The effect of thermal-induced sapphire substrate erosion on material characteristics of sputtered β-Ga2O3 film has been investigated. Both the furnace and rapid thermal annealing (RTA) were performed in the air ambient for the post thermal treatments. After the annealing process, all the deposited films transformed from amorphous to monoclinic crystalline structure with excellent transmittance above 80% in the visible region. Meanwhile, a thermal-induced interdiffusion phenomenon has been observed in β-Ga2O3/sapphire architecture, particularly for furnace-annealed samples. Even though high-temperature post thermal treatments can enhance the crystallinity of the Ga2O3 films continuously, a degraded photodetector performance is observed for the samples annealed above 800 °C due to the thermal-induced aluminum (Al) diffusion issue. The interdiffusion mechanism for the sputtered Ga2O3-on-sapphire films is proposed and its effects on material and photodetector characteristics are elucidated. An optimum metal-semiconductor-metal photodetector performance is achieved for the 800°C-RTA-treated Ga2O3 sample with the photo/dark current ratio of 1.78 × 105 and responsivity of 0.553 A/W (at 5 V bias).

Homogeneous annealing of TiO2, ZrO2 and ITO sol-gel layers with CO2 laser

Laser annealed sol-gel layers have the potential to replace the furnace process and expand the field of applications for selective annealed sol-gel coatings. In this study laser annealed TiO2, ZrO2 and ITO layers on glasses are investigated. Processing parameters of the CO2-laser system such as scanning speed, line overlap, laser power and focal spot are evaluated to generate sufficient thermal energy for densification. The ITO annealing process results in a sheet resistance comparable with the furnace annealed samples. Microscope images of the TiO2 and ZrO2 samples show a homogeneous layer morphology. XRD images exhibit crystalline tetragonal ZrO2 as seen in thermally annealed layers.

Effects of different annealing processes on optoelectronic and bending fatigue properties of AgZr and ITO/AgZr thin film metallic glass

Transparent conducting oxide (TCO) films are widely used throughout the optoelectronics industry. The present study explores the optoelectronic responses of AgZr (AZ) and ITO/AgZr (IAZ) thin film metallic glasses (TFMGs) with different Ag and Zr compositions and processed by two different annealing methods, namely furnace annealing (FA) and laser annealing (LA). Among the various as-deposited AZ and IAZ films, the ITO/Ag66Zr34 (IA6Z) film has the highest optical transmittance (55.7%) and the lowest sheet resistance (145.8 Ω/□) For the FA samples, an annealing temperature of 300 °C results in the optimal optoelectronic properties, namely a transmittance of 68.4% and a sheet resistance of 47.2 Ω/□. For the LA samples, the optimal processing conditions (a pulse energy of 2.5 μJ and a repetition rate of 150 kHz) yield optical transmittance and sheet resistance values of 64.0% and 17.8 Ω/□ respectively. The optimal LA processing conditions increase the Haacke figure of merit of the IA6Z sample from 2.0 × 10−5 in the as-deposited condition to 6.5 × 10−4 Ω−1 under the annealed condition; corresponding to a 32.5-fold improvement. Finally, the relative change in resistivity (ΔR/R0, where R0 is the initial resistivity, Ri is the measured resistivity after a certain number of cycles, and ΔR is Ri− R0) of the as-deposited IA6Z sample following fatigue testing (10,000 cycles) with a bend radius of 7 mm (ΔR/R0=0.49) is significantly lower than that of a pure ITO film of roughly equivalent thickness (ΔR/R0=0.93).

Reduced Graphene Oxide on Nickel Foam for Supercapacitor Electrodes.

The focus of this paper is the investigation of reduced graphene oxide (GO)/nickel foam (RGON) samples for use as supercapacitor electrodes. Nickel foam samples were soaked in a GO suspension and dried before being subjected to two different methods to remove oxygen. Atmospheric pressure annealed (APA) samples were treated with a varying number (10–18) of nitrogen plasma jet scans, where sample temperatures did not exceed 280 °C. Furnace annealed (FA) samples were processed in an atmosphere of hydrogen and argon, at temperatures ranging from 600 °C to 900 °C. Environmental Scanning Electron Microscope (ESEM) data indicated that the carbon to oxygen (C:O) ratio for APA samples was minimized at an intermediate number of plasma scans. Fourier Transform Infrared Spectroscopic (FTIR) and Raman spectroscopic data supported this finding. ESEM analysis from FA samples showed that with increasing temperatures of annealing, GO is transformed to reduced graphene oxide (RGO), with C:O ratios exceeding 35:1. X-ray Photoelectron Spectroscopy (XPS) and X-ray diffraction (XRD) data indicated the formation of RGO with an increasing annealing temperature until 800 °C, when oxygen reincorporation in the surface atomic layers becomes an issue. Supercapacitors, constructed using the FA samples, demonstrated performances that correlated with surface atomic layer optimization of the C:O ratio.

Mixed exchange-coupled soft α-(Fe80Pd20) and hard L10FePd phases in Fe64Pd36 thin films studied by first order reversal curves

Fe64Pd36 thin films have been fabricated by thermal evaporation onto single-crystal Si(100) substrates. After suitable thermal treatments, we demonstrate that two different magnetic phases can coexist in the same alloy, one α-(Fe80Pd20) which is magnetically soft, and one L10 FePd which is magnetically hard, giving rise to exchange coupling between them through their interfaces, without needing to artificially nanostructure the material. The structural and magnetic properties of as-prepared and furnace annealed samples are therefore studied by means of X-ray diffractometry, conversion electron Mössbauer spectroscopy, atomic and magnetic force microscopy and high sensitivity magnetometry.As prepared samples are characterised by different phases having soft magnetic properties: α-(Fe80Pd20) and disordered (fcc) FePd phases with different compositions. Furnace annealing in vacuum at 600°C for one hour promotes the transformation of the fcc phases into the L10 one, while α-(Fe80Pd20) remains largely unaffected. The structural transformations are accompanied by an increase of the coercive field without any significant changes of the saturation magnetisation value. In the sample annealed at 600°C, magnetisation reversal occurs in two steps: one at lower fields, attributed to the soft phase, and one at much larger fields, attributed to the hard phase and to the fraction of the soft one coupled to it. The exchange coupling between the two phases is demonstrated and thoroughly analysed by means of first order reversal curves.

Laser assisted crystallization of ferromagnetic amorphous ribbons: A multimodal characterization and thermal model study

This paper focuses on laser-based de-vitrification of amorphous soft magnetic Fe-Si-B ribbons and its consequent influence on the magnetic properties. Laser processing resulted in a finer scale of crystallites due to rapid heating and cooling during laser annealing compared to conventional furnace annealing process. A significant increase in saturation magnetization is observed for laser-annealed ribbons compared to both as-received and furnace annealed samples coupled with an increase in coercivity compared to the as received samples. The combined effect of thermal histories and stresses developed during laser annealing results in the formation of nano-crystalline phase along the laser track. The phase evolution is studied by micro-XRD and TEM analysis. Solute partitioning and compositional variation within the phases are obtained by Local Electrode Atom probe analysis. The evolution of microstructure is rationalized using a Finite Element based heat transfer multi-physics model.

Sol-flame synthesis of hybrid metal oxide nanowires

Hybrid metal oxide nanowires (NWs), with small characteristic diameter and large aspect ratio, can have unique and yet tunable chemical, optical and electrical properties by independently controlling the chemical compositions and morphologies of the individual components. Such hybrid NWs are promising building blocks in many applications, such as catalysis, sensors, batteries, solar cells and photoelectrochemical devices. However, these applications are hindered by the lack of scalable and economic methods for the synthesis of hybrid NWs. Here, we report a simple, scalable and new sol-flame method to synthesize various hybrid metal oxide NWs, including nanoparticle-shell decorated NWs (NP-shell@NW), NP-chain decorated NW (NP-chain@NW) and doped NWs. The sol-flame process first coats existing NWs with NPs or dopants precursors prepared by the sol–gel process, and then dissociates/oxidizes these precursors in flame. The sol-flame method uniquely combines the merits of the flame process (e.g., high temperature and fast heating rate) with low temperature sol–gel method (e.g., broad material choices and excellent chemical composition control). For both the NP-shell@NW and NP-chain@NW cases, the high temperature flame, compared to furnace, provides much faster heating rate and shorter duration for annealing, which evaporates and burns the precursor solvent rapidly, causing NPs to quickly nucleate around NWs without significant agglomeration. Hence, higher loading density of NPs with smaller sizes is decorated to the NWs, and the formed hybrid NP@NW exhibits significantly higher catalytic activity than that of the furnace-annealed sample. Similarly when using the sol-flame method to dope NWs, the high temperature flame enables rapid dopant diffusion and short annealing duration that maintains the morphology of the original materials and protects the delicate NW substrates from damage. We believe that the new sol-flame method can be applied to synthesize various 1-D hybrid metal oxide nanostructures, thereby impacting diverse application fields.

Millisecond annealing for advanced doping of dirty-silicon solar cells

Cost reduction is the overall goal in the further development of solar cell technologies. Multicrystalline silicon has attracted considerable attention because of its high stability against light soaking. In case of solar grade mc-Si, the rigorous control of metal impurities is desirable for solar cell fabrication. Although ion implantation doping got very recently distinct consideration for doping of monocrystalline solar material, efficient doping of multicrystalline solar material remains the main challenge to reduce costs. The influence of different annealing techniques on the optical and electrical properties of mc-Si solar cells was investigated. Flash lamp annealing (FLA) in the ms-range is demonstrated here as a very promising technique for the emitter formation at an overall low thermal budget. It could be presented that FLA at 1000 °C for 3 ms even without preheating is sufficient to recrystallize implanted silicon. The sheet resistance of FLA samples shows the values of about 50 Ω/sq. Especially, the minority carrier diffusion length for the FLA samples is in the range of 80 μm without surface passivation. This is up to one order of magnitude higher than that observed from rapid thermal annealing or furnace annealing samples. This technology shows great promise to replace the conventional POCl3-doping.

Rapid thermal annealing of size-controlled Si nanocrystals: Dependence of interface defect density on thermal budget

Photoluminescence properties of size-controlled Si nanocrystals (NCs) formed by various annealings have been studied in detail. The thermal treatments involve rapid thermal annealing (RTA, 10 to 180 s) as well as conventional tube furnace annealing (1h) at 1100 °C. Whereas the photoluminescence (PL) peak positions and the TEM images indicate only minor changes in NC size, the PL intensity varies over more than two orders of magnitude. A correlation between the total thermal budget applied by the different annealing treatments and the PL intensity is demonstrated. In addition, the PL improvement of interface defect passivation by post-annealing in H2 ambient is investigated. RTA with H2 passivation is not able to achieve the PL intensity and NC interface quality of conventionally annealed and passivated samples. The combination of these results with our previous electron spin resonance studies allows to estimate the interface defect densities. Tube furnace annealed samples after H2 treatment have less than 2% defective NCs. In contrast, more than 95% defective NCs are assumed for a 180 s RTA.

Effects of deposition temperatures and annealing conditions on the microstructural, electrical and optical properties of polycrystalline Al-doped ZnO thin films

Al-doped ZnO (AZO, ZnO:Al2O3=98:2wt%) films are deposited on different substrates by an RF magnetron sputtering and subsequently annealed at three different conditions to investigate the microstructural, electrical, and optical properties. X-ray diffraction and scanning electron microscope results show that all the samples are polycrystalline and the samples rapid-thermal-annealed at 900°C in an N2 ambient contain larger grains compared to the furnace-annealed samples. It is shown that the sample deposited at room temperature on the sapphire gives a resistivity of 5.57×10−4Ωcm when furnace-annealed at 500°C in a mixture of N2:H2 (9:1). It is also shown that the Hall mobility vs. carrier concentration (μ–n) relation is divided into two groups, depending on the annealing conditions, namely, either rapid-thermal annealing or furnace annealing. The relations are described in terms of either grain boundary scattering or ionized impurity scattering mechanism. In addition, the samples produce fairly high transmittance of 91–96.99% across the wavelength region of 400–1100nm. The optical bandgaps of the samples increase with increasing carrier concentration.

Residual stress study of silicon quantum dot in silicon carbide matrix by Raman measurement

AbstractTwo different annealing processes have been applied on Silicon rich SiCX amorphous samples: furnace annealing at 1100 °C/1hr and RTA at 1100 °C/30 sec. After annealing, both Si and SiC nanocrystals were clearly observed from TEM image and evaluated from XRD results. Peak position of Raman results are more blue shifted from Si reference wafer position in RTA samples (Δ=5.4 cm‐1) compare with furnace annealing samples (Δ=2 cm‐1), indicating greater tensile stress is applied on Si nanocrystals. This is because of different thermal expansion coefficient of Si and SiC crystals and fast temperature ramping rate in RTA process. In order to release the stress in RTA samples, additional annealing process has been applied. Raman analysis indicates, after applying an additional furnace annealing, all samples with different Si concentration could release most of the residual stress. But residual stress in low Si concentration samples could not be as well released by additional RTA due to insufficient time duration. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Microstructure and electrical properties of high power laser thermal annealing on inkjet-printed Ag films

In this work, a high power continuous-wave (CW) Nd:YAG laser was used for thermal treatment of inkjet-printed Ag films – resulting in the elimination of organic additives (dispersant, binder, and organic solvent) in the Ag ink and annealing of Ag nano-particles. By optimizing laser parameters such as laser power and defocusing value, the laser energy can be totally converted into heat energy, which is used for thermal treatment of inkjet-printed Ag films. This results in the microstructure and the resistivity of the films to be controlled. We investigated the thermal diffusion mechanisms during laser annealing and the resulting microstructures. The impact of high power laser annealing on microstructures and electrical characteristics of inkjet-printed Ag films was compared to those of the films annealed by a conventional furnace annealing. Focused ion beam (FIB) channeling images show that the laser annealed Ag films have large columnar grains and a dense void-free structure, while furnace annealed films have much smaller grains and exhibit void formation. As a result, the laser annealed films have better electrical properties (low resistivity) compared to furnace annealed samples.

L 1 0 ordering of FePt thin films using sub-10 ms laser pulses

The structural and magnetic properties of 10 nm FePt thin films annealed using a 1064 nm wavelength laser with 10, 7.5, 5.0, and 2.5 ms pulses have been examined. The A1 to L10 phase transformation was confirmed by x-ray diffraction (XRD). The maximum order parameter of 0.53 and coercivity of 5.36 kOe can be obtained with 10 ms pulse width laser annealing at a laser energy fluence of 10 J/cm2. The order parameter of the furnace annealed samples was approximately 1.0 suggesting that 10 ms is insufficient to obtain a fully ordered phase. The laser annealed grain size, as measured by in-plane XRD analysis, is 24 % smaller than that of furnace annealed sample for an equivalent order parameter demonstrating the merit of short time annealing.

Influence of annealing on the Er luminescence in Si-rich SiO2 layers coimplanted with Er ions

The impact of rapid thermal annealing (RTA) in producing samples by sequential implantation of Si and Er ions into a 200 nm SiO2 layer combined with different annealing cycles as well as the corresponding room-temperature visible and infrared photoluminescence (PL) have been studied. The Er-related PL intensity at 1533 nm for the samples prepared by implanting Si with subsequent annealing, followed by Er implantation, and final annealing (type I) was found to be stronger than the one produced similarly but without the first annealing step (type II). In fact, the 1533 nm peak intensity in the optimized RTA processed sample is comparable to the PL yield of the furnace-annealed sample. Moreover, the excitation wavelength (405 nm) was found to be suitable for exciting the Si=O related point defects in the SiO2 layer and can provide a PL band with a maximum at ∼580 nm. While this band was further intensified in the presence of Si nanocrystals (Si NCs), it became weaker by introducing additional Er3+ ions with a concomitant rise of the 1533 nm Er PL, confirming the visible range pumping of Er3+. The detailed spectral analyses suggest that the 580 nm band is the result of the excitation/deexcitation mechanism in molecule such as states in the Si=O or the Si=O state mediated recombination of carriers in Si NCs according to the model proposed by [Wolkin et al., Phys. Rev. Lett. 82, 197 (1999)]. The samples were further characterized by transmission electron microscopy and Fourier-transform infrared spectroscopy. The time-resolved PL measurements and a modeling by rate equations were also performed to determine and justify the energy migration mechanism from Si NC to the neighboring Er3+.

Characterization of radiation damage annealing of recoil-implanted GaP

The recovery of crystallinity as a function of annealing temperature in GaP recoil-implanted with 111In has been monitored on an atomic scale using the perturbed angular correlation (PAC) technique. This technique is based on hyperfine interaction of the electric quadrupole moment of probe nuclei with the electric field gradient (EFG) of the host lattice. The 111In/Cd probe nuclei were recoil-implanted at room temperature with an energy of up to 8 MeV following heavy-ion nuclear fusion evaporation reactions. Measurements were performed at room temperature for as-implanted and furnace annealed samples. Isochronal annealing in ambient nitrogen up to 950 °C showed a progressive reduction of disorder around the probe nuclei as indicated by a continual decrease in the width of the EFG distribution. These measurements suggest that recoil implantation did not result in drastic damage to the sample, and that annealing at 800 °C for 30 min is sufficient to produce an optimum recovery of crystallinity. Also, complementary double crystal X-ray diffraction measurements were in qualitative agreement with the results derived from PAC.

Magnetic and magnetotransport properties of Fe-based glass-covered microwires

Magnetic and magnetotransport properties of glass-covered amorphous microwires of nominal composition Fe89B1Si3C3Mn4 have been studied. Samples of two families with the same composition but different metallic core diameters were annealed in a furnace or by Joule heating. The electrical resistance was measured as a function of time during annealing to study the effects on the samples' microstructures (evolution from the amorphous to the crystalline phase). Static hysteresis loops were measured on all samples by means of a vibrating sample magnetometer. Giant magneto-impedance measurements (GMI) performed on a coaxial line using a vectorial network analyser at frequencies up to 6 GHz showed that furnace-annealed samples display larger anisotropies with respect to Joule-heated ones; however, Joule heating is more effective in improving the magneto-impedance response of the alloy. The maximum GMI ratio is ≈ 175% at 4 GHz. The influence of the different metallic core/total wire diameter on the induced anisotropies has been studied for the two families of samples through hysteresis loops and high-frequency GMI.

Large gyromagnetic effect in as-cast and post-production treated amorphous wires

Abstract The large gyromagnetic effect (LGE) in highly positive magnetostrictive Fe 77.5 Si 7.5 B 15 amorphous as-cast, furnace annealed with and without axial tension, current annealed, and transverse field annealed wires was investigated. A slight decrease in the rotation frequency of the LGE was observed in the annealed samples. Results on the influence of a localised dc bias field on the LGE of as-cast and furnace annealed samples are reported for the first time. The localised dc bias field applied along the length of the wires significantly influences both frequency and direction of the wires’ rotation.