Effect Of High-temperature Annealing Research Articles

Enhancing the corrosion resistance of high Mo S31254 super austenitic stainless steel using grain boundary engineering

Super austenitic stainless steel (SASSs) with a high Mo content exhibit excellent resistance to intergranular corrosion (IGC), Its mechanical properties mainly depend on solid solution strengthening. Meanwhile, grain boundary engineering (GBE) can simultaneously improve the corrosion resistance and mechanical properties of Mo-rich austenitic stainless steel using the resistance to IGC of Mo. However, recrystallization annealing is extremely difficult due to the sensitive precipitation of Cr-rich and Mo-rich precipitations in SASSs. Therefore, this study explores the effect of large deformation, high temperature, and short-time annealing on the corrosion resistance of SASSs. The results show that a recrystallized organization with an average grain size of 13.3 μm was prepared by 50% cold rolling deformation and 2 min high-temperature short-time annealing at 1150 °C. The highest percentage of Σ3 GBs is about 34%, the percentage of other low-energy GBs is relatively low (only about 6%), and the rest are random high-angle grain boundaries (RHAGBs), which account for about 60%. It can be seen the corrosion resistance of random GBs after GBE treatment is superior to that of solution treatment. Meanwhile, medium-temperature aging improved the resistance to IGC of SASSs, especially after aging at 450 ℃, a small amount of Mo is enriched along the GBs, which promotes the formation of Cr2O3 and Mo-rich oxides in the passivation film and improves the corrosion resistance. The above results provide guidance for improving the corrosion resistance of Mo-rich austenitic stainless steels.

Effects of high-temperature annealing on vacancy complexes and luminescence properties in multilayer periodic structures with elastically strained GeSiSn layers

Effects of postgrowth high-temperature annealing on vacancy complexes and photoluminescence (PL) from GeSiSn/Si multiple quantum wells (MQWs) are studied. The series of PL peaks related to the vacancy-tin complexes was observed for as-grown samples including different structures, such as GeSiSn/Si MQWs, multilayer periodic structure with GeSiSn quantum dots (QDs), GeSn cross-structures upon GeSiSn/Si MQWs, and thick GeSiSn layers. The PL band intensity is significantly reduced after annealing at 700 °C corresponding to the reduction in vacancy density, as demonstrated by the positron annihilation spectroscopy (PAS) data. Such annealing also results in the appearance of the PL signal related to the interband optical transitions in GeSiSn/Si MQWs. However, the high temperature could negatively impact the sharpness of heterointerfaces due to Sn diffusion, thus limiting the PL efficiency. To improve the luminescence properties of GeSiSn/Si structures, we proposed a two-stage technique combining both the annealing and subsequent treatment of samples in a hydrogen plasma at 200 °C. The plasma treatment significantly reduces the PL band of vacancy-related defects, whereas annealing at a moderate temperature of ∼600 °C prevents the blurring of heterointerfaces. As a result, we demonstrate an increase in the relative efficiency of interband PL of type II GeSiSn/Si MQW structures emitting in the range of 1.5–2 μm.

Evolution of extended defects in UO2 during high temperature annealing

The evolution of thermophysical characteristics of uranium oxide (UO2) under irradiation is a critical aspect of nuclear fuel performance of light water reactors. This study examines the effect of high-temperature annealing at 1000 °C - 1600 °C on defect evolution in krypton irradiated UO2 at room temperature. Transmission electron microscopy analysis reveals that the size of irradiation-induced bubbles and dislocation loops increases but their density decreases with annealing temperatures. Perfect dislocation loops with b⇀ = <110> dominate, regardless of the annealing temperature. A rate theory model for extended defect evolution is applied to conclude that current understanding of dynamical loop and bubble evolution at high-temperature annealing is governed by defect coalescence.

On the effect of high-temperature annealing on the microstructure and mechanical properties of a hot-rolled 90W7Ni3Fe tungsten heavy alloy

We previously reported on commercial 90W7Ni3Fe (90W, wt. %) tungsten heavy alloy (WHA) plates, which were hot-rolled (HR) at 900 °C to thickness reductions of 62 %, 74 % and 87 % (62R, 74R and 87R), and an as-sintered (AS) 90W plate. In contrast to 62R and 74R, the 87R WHA was given a final processing heat treatment (HT) at 1400 °C/3 h (87RHT). HR deforms the WHA microstructure into an anisotropic brick (W) and mortar (NiWFe ductile phase) composite architecture. Fracture toughness tests showed that after the processing HT, the 87RHT plate experienced stable crack growth, with an average elastic-plastic fracture toughness of KJm ≈ 116 ± 20 MPa√m, somewhat higher than the AS KJm ≈ 97 ± 18 MPa√m. This compares to elastic fracture toughness of KIm ≈ 35 ± 2 MPa√m in the 62R and 74R conditions, absent a final HT. Here, we report on the microstructures and mechanical properties of four new WHA conditions following an additional recovery anneal at 1300 °C/24 h. The recovery anneal results in similar average elastic-plastic toughness of KJm ≈ 125 ± 12 MPa√m in all four processing conditions, which is slightly higher than for the AS and 87RHT WHA, and much higher than for the 62R and 74R WHA, without the processing HT. Scanning electron microscopy and electron backscatter diffraction showed that the final 1300 °C/24 h anneal recovers the hardening microstructures in the 62R and 74R WHA. The lower strength promotes crack tip microcracking dilatational shielding, which increases the WHA fracture toughness. The implications of these results to the design of WHA are briefly discussed.

Thermal stability of Ni3Al microstructure and microhardness after spark plasma sintering

The effect of high-temperature annealing on the structural-phase state and microhardness of Ni3Al samples obtained by spark plasma sintering after high-energy ball milling has been studied. Using X-ray diffraction analysis, scanning and transmission electron microscopy, a comparative study of the features of the structural-phase state of Ni3Al samples depending on the duration of preliminary high-energy ball milling and annealing temperature was carried out. Temperatures have been identified that ensure simultaneous grain growth at a high density of nuclei, which contributes to the formation of a fine-grained structural state. Depending on the state of the material, the corresponding microhardness values have been determined. The influence of the annealing temperature on the strengthening mechanisms has been analyzed.

Effect of High-Temperature Annealing on the Structure and Properties of a Composite Material Based on TiC/TiB2/Ti3SiC2

Effect of High-Temperature Annealing on the Structure and Properties of a Composite Material Based on TiC/TiB2/Ti3SiC2

Effect of high temperature annealing on the microstructure evolution and hardness behavior of the Inconel 625 superalloy additively manufactured by laser powder bed fusion

Additive manufacturing of Inconel 625 components attracts great interest due to its ability to produce parts with complex geometries that are needed for high-temperature applications in the aerospace, energy, automotive and chemical industries. To take full advantage of the potential of additive manufacturing, an in-depth understanding of the effects of prolonged high-temperature annealing on microstructure and hardness evolution is needed. Previous research in this field has mainly focused on a limited range of temperature and time. This study aims to determine the effect of prolonged high-temperature annealing on the evolution of intermetallic phases and carbides, as well as changes in the dislocation substructure of Inconel 625 superalloy additively manufactured by laser powder bed fusion subjected to stress relief annealing and subsequent isothermal annealing at a temperature up to 800 °C for 5–500 h. The microstructure development is correlated with hardness behaviour. It is determined that the microstructure evolution proceeds in four stages with temperature and time increase. In the initial stress-relieved condition, a cellular microstructure with nano-sized precipitates of the Laves phase and NbC carbides at the cell walls occurs, and hardness is equal to 300 HV10. In the 1st stage of the microstructure evolution, the γ'' phase particles precipitate on the cell walls, which results in hardening up to 383 HV10 in the specimen annealed at 700 °C for 5 h. The 2nd stage involves the precipitation of the γ'' phase both on the cell walls and inside the cells, as well as the formation of dislocation networks, which contribute to the softening effect and hardness drop to 319 HV10. In the 3rd stage, at temperature 700 and 800 °C, the δ phase, M23C6 carbides, and the Laves phase precipitate and grow, and the subgrain boundaries are formed. The hardness is in the range of 340–350 HV10 and is higher than in the 2nd stage. In the 4th stage, as the annealing time is increased at a temperature of 800 °C, the δ phase and M23C6 carbides coagulate, and the Laves phase particles spheroidize or partially dissolve. Very intense precipitation and growth of the hard δ phase particles provide an increase in hardness to 402 HV10. As a result of systematic studies, the various strengthening and softening mechanisms acting during high-temperature annealing are determined.Graphical abstract

Investigation of thermal annealing on the characteristics of ScxAl1−xN thin films

Good temperature stability is essential for radio-frequency (RF) devices working at high frequencies. AlN and Sc doped AlN (ScxAl1−xN) are widely used as piezoelectric thin films for their excellent performance, but the temperature characteristics of these two materials could be more precise. In this work, the effect of high-temperature thermal annealing on the characteristics of ScxAl1−xN thin films was investigated. ScxAl1−xN thin films with different Sc compositions were deposited and then annealed in different atmospheres at various temperatures. It was found that ScxAl1−xN thin films could maintain good temperature stability below 900 °C in vacuum or air, and AlN can even maintain up to 1300 °C under vacuum. When the annealing temperature exceeded 900 °C, the films’ crystallinity and lattice would appear to have apparent changes. Moreover, the introduction of oxygen at elevated temperatures could impair the surface morphologies and mechanical properties of the ScxAl1−xN thin films. The results revealed that the increased Sc composition decreased the temperature stability of the ScxAl1−xN thin films, and AlN was proved to have better temperature stability than the other two thin films. This work establishes a research foundation for utilizing ScxAl1−xN thin films in high-temperature applications.

Influence of Post-Ion-Implantation Annealing Temperature on the Characteristics of Gate Oxide on 4H Silicon Carbide

The effect of post-ion implantation annealing on the properties of the SiO2/4H-SiC interface is examined in this paper. It is observed that the surface roughness degrades after the high-temperature Ar annealing, but the oxidation process after the high temperature annealing can improve the surface roughness. To better understand the effect of high-temperature annealing on the gate oxide, the reliability of gate oxide is further studied. The results show that although the surface roughness degrades after high-temperature annealing, the interface state density, tunneling barrier height, breakdown field, and critical electric field for the 10-year lifetime of the thermally grown gate oxide do not degrade.

Assessing the stability of p+ and n+ polysilicon passivating contacts with various capping layers on p-type wafers

Polysilicon (poly-Si)-on-oxide passivating contact structures (POLO/TOPCon) enable high-efficiency solar cells as they simultaneously provide a very high level of surface passivation and a high conductance for either electrons or holes. The ease of incorporation with existing manufacturing lines and their tolerance for high-temperature processing has increased the wide acceptance of this structure in the PV industry. In this report, we explore the effects of short high-temperature annealing required for effective hydrogenation and formation of ohmic screen-printed contacts across a wide temperature range (636 °C–846 °C) on the stability of passivating contact structures. We study this on p-type c-Si substrates with phosphorus-doped (n-type) or boron-doped (p-type) polysilicon contacts capped with either an AlOx or SiNx coating. Our experimental results show that irrespective of the poly-Si doping type, AlOx-capped samples suffer a loss in surface passivation across the investigated temperature range, while SiNx-capped samples show an improvement at lower annealing temperatures. Above 744 °C, severely ruptured blisters occur for the samples coated with a SiNx layer, leading to lift-off of the poly layer in extreme cases, and in all cases, significant surface passivation losses, up to 99%. A study of the long-term stability of these fired samples under 1-sun illumination @ 140 °C shows that they suffer from both bulk and surface-like instabilities. Two degradation cycles were observed: the first, a boron-oxygen light-induced degradation (BO-LID) observed after 5 min, with capture cross-section ratios of 15.8–19.2, and a slower secondary degradation, similar to light and elevated temperature-induced degradation (LeTID), with maximum degradation reached after ∼ 14 days. The presence of a silicon nitride layer does not appear to influence the kinetics of post-degradation recovery. Our results suggest that the effect of firing may be influenced by the polarity of the bulk c-Si or perhaps the chemistry of the SiNx film and highlight that passivating contact structures based on p-type c-Si may offer better long-term stability than those based on n-type c-Si.

Effect of surface preparation by high-temperature hydrogen annealing on the passivation of Ni-20 at.% Cr alloy in sulfuric acid

The effect of high-temperature annealing under hydrogen gas (H2) surface preparation on a binary polycrystalline Ni-20 at.% Cr alloy was investigated in comparison with conventional mechanical grinding surface preparation. Duplex surface films with inner Cr(III) oxide and outer Ni(II) and Cr(III) hydroxide layers natively formed before and after H2 annealing were characterized by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy. A thinner and less homogeneous inner barrier layer formed after H2 annealing caused an oxidation peak at the active/passive transition in the linear sweep voltammetry measurement in a 0.5 M H2SO4 solution. Despite this high oxidation peak, passivation of the H2 annealed surface resulted in the formation of a more corrosion resistant inner layer than on the mechanically ground surface, as demonstrated by electrochemical impedance spectroscopy. The corrosion resistant passive film formation of the H2 annealed surface is attributed to the increased Cr enrichment of the inner layer caused by the selective Ni dissolution providing corrosion resistance to the initially weakly protected sites of the natively formed surface film.

Stability of the Structural and Transport Characteristics of (ZrO2)0.99−x(Sc2O3)x(R2O3)0.01 (R–Yb, Y, Tb, Gd) Electrolytic Membranes to High-Temperature Exposure

The effect of long-term high-temperature annealing on the phase composition, local crystal structure, and oxygen-ion conductivity of SOFC membranes based on zirconium dioxide solid solutions was studied. Crystals with the composition of (ZrO2)0.99-x(Sc2O3)x(R2O3)0.01 (where x = 0.08-0.1; R-Yb, Y, Tb, Gd) were obtained by the method of directed melt crystallization in a cold crucible. The crystals were annealed in air at a temperature of 1000 °C for 400 h. The phase analysis of the crystals before and after annealing was studied by X-ray diffractometry and Raman spectroscopy. The study of the ionic conductivity of the crystals was carried out by the method of impedance spectroscopy in the temperature range 400-900 °C. It has been shown that when various rare earth cations (Yb, Y, Tb, and Gd) are used, the maximum conductivity is observed for the compositions (ZrO2)0.91(Sc2O3)0.08(Yb2O3)0.01, (ZrO2)0.89(Sc2O3)0.1(Y2O3)0.01, (ZrO2)0.90(Sc2O3)0.09(Tb2O3)0.01, and (ZrO2)0.89(Sc2O3)0.1(Gd2O3)0.01. At the same time, these crystals have a highly symmetrical pseudocubic structure, which is retained even after crystal annealing. At comparable concentrations of Sc2O3, the conductivity of crystals decreases with an increase in the ionic radius of the rare earth cation. The high-temperature degradation of the conductivity is also discussed depending on the type of rare earth oxide and the concentration of scandium oxide.

Effect of High Temperature Annealing on the Physicochemical Properties of systems based on FeSi-=SUB=-x-=/SUB=-

It has been established that the physicochemical properties of structures based on iron silicides formed by ion implantation of iron ions into silicon depend significantly on the time of subsequent high-temperature annealing. Objects with different geometric parameters are formed on the surface and the roughness increases. Annealing at 1000 o C in an Ar atmosphere is accompanied by a decrease in the content of the Fe-Si chemical bonds during the first 60 seconds. The reason for the drop in thermal conductivity with increasing annealing temperature is the formation of silicide complexes. Keywords: iron silicide, thermoelectric, ion implantation, chemical composition, X-ray photoelectron spectroscopy.

Effect of High-temperature Annealing on AlN Crystal Grown by PVT Method

Effect of High-temperature Annealing on AlN Crystal Grown by PVT Method

Effect of high-temperature annealing on mechanical properties of spark plasma sintered TiCN-15WC-5Cr3C2-5 nano-TiB2 cermets modified with cobalt

Effect of high-temperature annealing on mechanical properties of spark plasma sintered TiCN-15WC-5Cr3C2-5 nano-TiB2 cermets modified with cobalt

The Internal Structure of Lanthanide-Doped Nanoparticles and the Effect of High-Temperature Annealing on Their Luminescent Properties

Up-converting nanoparticles are widely studied for a wide range of applications based on their unique optical properties, with NaYF4 nanoparticles doped with Yb3+ and Er3+ receiving particular attention. While developing this material in nanoparticle form extends their potential applications, the resulting nanoparticles have proven less efficient up-converters than their bulk counterpart. Reported up-conversion quantum yields are significantly lower, even when very thick shells were grown to eliminate quenching by surface defects and surface-bound molecules. This raises the question whether the internal structure of these particles contributes to the lower quantum yield. In our work, we investigated the internal structure of NaYF4:Yb3+ and Er3+ NPs using high-resolution scanning energy dispersive X-ray spectroscopy, generating two-dimensional elemental maps. We deduced that the ions are not distributed homogeneously in the nanoparticles as made via a colloidal synthesis route. Heating the nanoparticles to temperatures used to anneal bulk crystals resulted in a homogeneous distribution, but an increase in emission intensity under similar measurement conditions was not observed. Vibrational spectroscopy showed the presence of OH– in dried nanoparticles, which might act as an internal quencher.

(Invited) ALD HfO2/β-Ga2O3 Reliability for Future Power Devices

The ultra-wide bandgap (UWBG) semiconductor, β-gallium oxide, has shown great potential in power devices due to its excellent electrical properties and availability of high-quality single-crystalline substrates. Significant progress has been made in the development of β-Ga2O3 metal-oxide-semiconductor (MOS) devices, but further progress will require optimization of the gate-dielectric interface. In this talk, I will describe the investigation of HfO2 dielectric reliability on β-Ga2O3 for future power devices. I fabricated β-Ga2O3 (010) MOS capacitors with atomic layer deposited (ALD) HfO2 and used capacitance-voltage (C-V) and current density-voltage (J-V) techniques to analyze the electrical reliability of ALD HfO2/β-Ga2O3 MOSCAPs. Positive bias stress measurements indicated that HfO2/β-Ga2O3 MOSCAPs are more susceptible to charge trapping at lower electric stress fields compared to HfO2/Si MOSCAPs, likely due to the smaller conduction band offset between HfO2 and β-Ga2O3. Initial flatband voltage shifts were observed for C-V sweeps of HfO2/β-Ga2O3 MOSCAPs, showing the significance of border traps within the dielectric. The lack of mobile holes in the β-Ga2O3 impedes the recombination of these trapped charges in the dielectric while the MOSCAP is in depletion. We observed full recovery from stress-induced charge trapping in the HfO2/β-Ga2O3 MOSCAPs upon deep ultra-violet illumination. The negative valence band offset between the dielectric and semiconductor allows the recombination of photo-generated holes with the trapped dielectric charges [1]. Because many fabrication steps require high temperature processing, we also investigated the thermal reliability of the ALD HfO2/β-Ga2O3 (010) interface. Negligible Ga atom diffusion was observed in secondary ion mass spectrometry (SIMS) depth profiles for anneals at temperatures up to 850°C in N2 environment for 10 minutes. Significant Ga diffusion into the HfO2 layer was observed upon annealing at 900°C, resulting in a severely degraded MOS structure. Additional analysis was performed to investigate the impact of high temperature processing on the MOS electrical characteristics [2].H.N.M was supported by a National Science Foundation Graduate Research Fellowship under Grant No. DGE 1256260. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. Portions of this work were performed at the Lurie Nanofabrication Facility and J. D. Hanawalt X-Ray MicroAnalysis Laboratory, which are supported by the College of Engineering at the University of Michigan.[1] H. N. Masten, J. D. Phillips, and R. L. Peterson, “Charge trapping and recovery in ALD HfO2/β-Ga2O3 (010) MOS capacitors,” Semicond. Sci. Technol., vol. 36, no. 4, p. 04LT01, Mar. 2021, doi:10.1088/1361-6641/abe880.[2] H. N. Masten, J. D. Phillips, and R. L. Peterson, “Effects of High Temperature Annealing on the Atomic Layer Deposited HfO2 /β-Ga2O3 (010) interface,” Journal of Applied Physics, Accepted.

Effect of High-Temperature Annealing on the Cross-Tension Property of Resistance Spot Welded Medium-Mn Steel

Effect of High-Temperature Annealing on the Cross-Tension Property of Resistance Spot Welded Medium-Mn Steel

Visible photoresponse of TiO2 nanotubes in comparison to that of nanoparticles and anodic thin film

Reports on the defective anodic titanium dioxide (TiO2) that harvests solar energy to perform photochemical reactions generating value-added chemicals and/or energy are scarce. In this study, we synthesize TiO2 with two different morphologies (i.e., nanotube and compact layer) on a Ti substrate in a fluoride- and sulfide-containing electrolyte by using the electrochemical anodization method. The effect of high-temperature annealing on various TiO2 structures and substrates in comparison with commercial TiO2 nanoparticles coated on fluorine-doped tin oxide substrate under different gaseous environments (i.e., Ar, air, and O2) is investigated herein by virtue of crystallinity, optoelectronic-physical properties, and photoelectrochemical performances. Unlike traditional TiO2 nanoparticles, which are only active in ultraviolet illumination and with severe aggregation, the anodic TiO2 nanotubes endow the effect of the oxygen vacancy and the self-doping of F− and S− ions upon annealing under the Ar environment, which is crucial to extending the photoresponse to the visible region. The gray anodic TiO2 obtained through thermal annealing at 450 °C crystallizes in the anatase phase and maintains an intact surface morphology under different gaseous environments. The electron paramagnetic spectra are used to confirm the presence of Ti3+ or oxygen vacancy. The entrapment of the F− and S− ions within TiO2 is determined by X-ray photoelectron spectroscopy and energy-dispersive spectroscopy introducing intrinsic defect states, which can resolve the bottlenecks in materials and encourages new paradigms beyond solar light-induced photocatalysis.

The Effect of High Temperature Annealing on Surface Wettability, Mechanical and Chemical Properties of Laser Ablated Nitinol Surface

The Effect of High Temperature Annealing on Surface Wettability, Mechanical and Chemical Properties of Laser Ablated Nitinol Surface