Effect Of Isothermal Annealing Research Articles

Effect of Isothermal Annealing on the Corrosion Resistance of Detonation Sprayed Fe-Based Amorphous Coatings

Effect of Isothermal Annealing on the Corrosion Resistance of Detonation Sprayed Fe-Based Amorphous Coatings

Effect of isothermal annealing on formation of self-assembled nanostructures in manganese spinel ZnMnGaO4

The effects of isothermal annealing on the self-assembled nanostructures of spinel manganese oxide ZnMnGaO4 were investigated using transmission electron microscopy and x-ray diffraction. The checkerboard nanostructures and zigzag nanostructures (named “Sierra” nanostructures) coexisted owing to the chemical phase separation of Mn3+ and Ga3+ ions by isothermal annealing at 575 °C. It was observed that the checkerboard nanostructures were dominant in short-time annealing and that the volume fraction of the Sierra nanostructures became more prominent as the annealing period increase. The interdiffusion of Mn3+ and Ga3+ is indicated to play an important role in gaining the total energy of the system by the reduction in the local strain caused by the formation of nanostructures. These results provide further insights into the fabrication of distinct types of nanostructures in complex transition-metal compounds.

Вплив аргонвмісного середовища відпалу на перебіг структурно-фазових перетворень в тонкоплівкових композиціях Ni/Ti

This study is focused on the effect of isothermal annealing in an argon atmosphere (200 Pa) in the temperature range of 200–600 °C on the evolution of diffusion-induced structural phase transformations in Ni/Ti layered thin films with different modulation period but similar total thickness of 60 nm. Changes in the structure and phase composition of nanoscale films have been examined using X-ray diffraction technique, and the chemical composition has been analyzed using secondary ion mass spectrometry. Annealing at 300 °C induces the development of diffusion interaction between the Ni and Ti layers, leading to the formation of intermetallic NixTiy phases of various stoichiometry at higher annealing temperatures. It is shown that an increased number of layers promotes a significant activation of diffusion processes between the components of the system, resulting in a change in its phase composition at lower annealing temperatures. Meanwhile, for all investigated samples, annealing at elevated temperatures (>500 °C) causes the agglomeration of Ti on the free surface with the probable formation of a protective oxide layer. It was established that the decisive influence on thermally induced phase formation is exerted by two competing factors: the use of an argon-containing annealing atmosphere contributes to the intensification of mass transfer processes between the materials of metal nanolayers compared to similar heat treatment in a vacuum, while the decrease of the modulation period of the thin-film system promotes the amorphization processes at the interface between metal layers with a corresponding inhibition of structural ordering processes. Keywords: nanoscale films, NiTi, diffusion, argon, isothermal annealing.

The Effect of Thermal Annealing on the Electrophysical Properties of Samples n-Si<Ni,Сu>

This paper presents the results of studies of the effect of isothermal annealing at temperatures T = 673¸1473 K in the time interval 5¸60 minutes on the electrical properties of silicon, simultaneously alloyed with nickel and copper. Samples of n-Si<Ni,Cu> were obtained on the basis of the starting material - single-crystal silicon, grown by the Czochralski method with the initial resistivity r = 0.3 Ohm×cm. Diffusion was carried out at a temperature of 1523 K for 2 hours. After that, the samples were cooled at a rate of 0.1 K/s. The morphological parameters of impurity nickel and copper atom clusters formed in the bulk of silicon were measured by electron probe microanalysis on a modern Superprobe JXA-8800R setup. As it turned out, in the volume of n-Si<Ni,Cu> samples, clusters of impurity atoms with different geometric shapes are formed, the sizes of which reach up to 500 nm. The electrical properties of the samples were studied by the Hall effect method using an Ecopia HMS-7000 instrument. It was revealed that under the influence of thermal annealing (TA) at T≥1273 K, impurity clusters decompose, which leads to an increase in the resistivity of n‑Si<Ni,Cu> samples. After exposure to TA at Т=1273 K for 15 minutes, the density of impurity nanoaccumulations of acicular and lenticular shapes sharply decreases in the sample volume. Under the influence of TA at T = 1473 K for 10 minutes in the volume of the sample, the decay of impurity nanoclusters with a spherical shape is observed. Also presented are the results of changes in the density of impurity clusters, as well as structural analyzes of the samples before and after exposure to thermal annealing.

The mechanical properties of austempered 1.75Ni-1.5Cu-0.5Mo alloyed PM steels

The effects of isothermal annealing on the microstructure and mechanical properties of ferrous based Ni-Cu-Mo-C diffusion alloy powder metallurgy (PM) components were investigated. For this purpose, the powder mixtures were pressed and sintered at 1150 °C. After full austenitisation at 825°C, they were kept isothermally in a neutral salt bath at 450°C for 15–120 min. Microhardness (HV 0.01), tensile and impact toughness tests of the samples were carried out at room temperature. The hardness value decreased with increasing austempering time. As a result of the austempering of 120 min, the tensile strength increased by 12.2% and became 460 MPa compared to the heat treatment period of 15 min, and the impact toughness was determined to be 14.3 j.cm−2 with an increase of 21%. Under the conditions in this experimental study, optimum strength and ductility values were obtained with austempering time applied in the range of 90–120 min.

Effect of Isothermal Annealing on Sn Whisker Growth Behavior of Sn0.7Cu0.05Ni Solder Joint

This paper presents an assessment of the effect of isothermal annealing of Sn whisker growth behavior on the surface of Sn0.7Cu0.05Ni solder joints using the hot-dip soldering technique. Sn0.7Cu and Sn0.7Cu0.05Ni solder joints with a similar solder coating thickness was aged up to 600 h in room temperature and annealed under 50 °C and 105 °C conditions. Through the observations, the significant outcome was the suppressing effect of Sn0.7Cu0.05Ni on Sn whisker growth in terms of density and length reduction. The fast atomic diffusion of isothermal annealing consequently reduced the stress gradient of Sn whisker growth on the Sn0.7Cu0.05Ni solder joint. It was also established that the smaller (Cu,Ni)6Sn5 grain size and stability characteristic of hexagonal η-Cu6Sn5 considerably contribute to the residual stress diminished in the (Cu,Ni)6Sn5 IMC interfacial layer and are able to suppress the growth of Sn whiskers on the Sn0.7Cu0.05Ni solder joint. The findings of this study provide environmental acceptance with the aim of suppressing Sn whisker growth and upsurging the reliability of the Sn0.7Cu0.05Ni solder joint at the electronic-device-operation temperature.

Research of Heat Resistance and Thermophysical Properties of the Diffusion Zone Formed by Annealing by Contact Melting Mode of the Layered Metal-Intermetallic Composite of the Cu-Al System

The results of studying the effect of isothermal annealing on structural, phase transformations, and thermal diffusivity in the diffusion zone of a Cu-Al layered metal-intermetallic composite (LMIC), obtained using technology including explosion welding, pressure treatment and heat treatment, are presented. It was found that, at 530 °C (the highest temperature, excluding the formation of a liquid phase in this system) with a holding time of up to 1000 h, there are no structural phase transformations in the Al (Cu)/CuAl2 metal-intermetallic composition, and a slight increase in its mass is associated with the formation of a thin dense protective oxide film on the surface. The thermal diffusivity of Cu-Al LMIC, obtained after removal of copper residues from the surface of the diffusion zone, is 50–60 W/m×K, which is significantly lower than that of copper (410 W/m×K) and aluminum (220 W/m×K).

NiO–ZnO based junction interface as high-temperature contact materials

Contact materials play a crucial role in an electronic device operating at moderate and elevated temperatures where chemical and thermal stability is of great importance. Oxide materials and their interfaces are potential candidates as high-temperature contact materials due to their high chemical and thermal stabilities. In this work, polycrystalline oxides of Ni0.98Li0.02O and Zn0.98Al0.02O were used to make junction interfaces, where the solid-state synthesis method was used to obtain the individual oxide materials. After assembly of the junction interfaces, properties such as electrical, chemical, and thermal stabilities of the interfaces were investigated. The electrical properties were assessed through current-voltage (I–V) and electrochemical impedance spectroscopy (EIS) measurements, where the interface revealed a transition from electrically rectifying to slightly ohmic contact within a temperature range from 500–1000 °C. After annealing the junction interfaces at these elevated temperatures, no secondary phase was observed at the junction interface, i.e., the interfaces remain chemically stable. Moreover, the effect of isothermal annealing on the I–V characteristics curve of the junction showed an increased reverse current output over long annealing time, attributed mainly to the increased effective contact area at the junction interface and cation inter-diffusion processes. Furthermore, an investigation of the cation inter-diffusion mechanism revealed mainly lattice diffusion of Zn2+ into Ni0.98Li0.02O, while Ni2+ diffusion into Zn0.98Al0.02O exhibited both lattice and grain-boundary diffusion mechanisms.

Effect of Isothermal Annealing on the Parameters of CuO Films Synthesized via Spray Pyrolysis and Sol–Gel Technology

Two ways manufacturing copper(II) oxide films are presented: spray pyrolysis and the sol–gel technique. The process for changing the resistivity of films at different temperatures depending on the duration of annealing is considered using the example of an obtained copper oxide film. The phase composition, degree of crystallization, and electrical resistance of the copper oxide film are determined.

Effect of isothermal annealing on mechanical performance and corrosion resistance of Ni-free Zr59Ti6Cu17.5Fe10Al7.5 bulk metallic glass

Ni-free Zr-Ti-Cu-Fe-Al bulk metallic glass (BMG) is regarded as a prospective candidate for practical applications. However, a high Ti content in the BMG causes a sharp deterioration of mechanical performance. Herein, the effects of isothermal annealing on the structure, mechanical performance, and corrosion resistance of the Zr59Ti6Cu17.5Fe10Al7.5 BMG are investigated. The alloy after a short-time annealing at 573 K shows admirable compressive strength and plasticity of 1910 MPa and 12.1%, respectively, which are much higher than 1733 MPa and 4.3% of the pristine BMG. This enhancement was ascribed to precipitation of ultrafine Al3Zr2 nanograins from the BMG matrix. However, the prolonged annealing induces propagation of nanocrystals and decreases free volume in the alloys, leading to the deterioration of mechanical performance. The electrochemical study demonstrates that the BMG maintains good corrosion resistance after the annealing. This work offers an avenue for designing high-performance Ni-free BMG-based alloys.

Post-Process Effects of Isothermal Annealing and Initially Applied Static Uniaxial Loading on the Ultimate Tensile Strength of Fused Filament Fabrication Parts.

Fused filament fabrication (FFF) is one of the most popular additive manufacturing (AM) techniques used to fabricate polymeric structures. However, these polymeric structures suffer from an inherent deficiency of weak inter-laminar tensile strength. Because of this weak inter-laminar strength, these parts fail prematurely and exhibit only a fraction of the mechanical properties of those fabricated using conventional means. In this paper, we study the effect of thermal annealing in the presence of an initially applied static uniaxial load on the ultimate tensile strength of parts fabricated using FFF. Tensile specimens or dogbones were fabricated from an acrylonitrile butadiene styrene (ABS) filament with a glass transition temperature (Tg) of 105 °C; these specimens were then isothermally annealed, post manufacture, in a fixture across a given range of temperatures and static loads. Tensile testing was then performed on these specimens to gauge the effect of the thermal annealing and static loading on inter-laminar tensile strength by measuring the ultimate tensile strength of the specimens. A design of experiments (DOE) approach was followed to calculate the main and interaction effects of the two factors (temperature and static loading) on the ultimate tensile strength, and an analysis of variance was conducted. Cross-sectional images of the specimens were studied to observe the changes in the mesostructure of the specimens that led to the increase in inter-laminar strength of the parts. The results show that temperature plays a dominant role in increasing the ultimate tensile strength and an 89% increase in the average ultimate tensile strength was seen corresponding to an annealing temperature of 160 °C. A change in the mesostructure of the parts is seen, which is characterized by an increase in bond length and void coalescence. These results can be helpful in studying the structural strength of 3D printed parts, and thus could eventually guide the fabrication of components with strength comparable to those of conventional manufacturing techniques.

Thermally promoted evolution of open-volume defects and Cu precipitates in the deformed FeCu alloys

We have studied the effect of isothermal annealing on the evolution of the open-volume defect and the Cu precipitate in deformed Fe0.15Cu, Fe0.3Cu and Fe0.6Cu alloys. Using the coincidence Doppler broadening, positron annihilation lifetime and the S-W couples, the evolution of local electronic circumstance around the annihilation sites, open-volume defects and interaction between open-volume defects and Cu precipitates were measured as a function of the isothermal annealing temperatures. Cold rolling deformation induced an obvious increment in S parameters due to the formation of open-volume defects. Annealing not only resulted in gradual recovery of open-volume defects and Cu thermal precipitation, but also promoted the combination and interaction between defects and Cu precipitates. The interaction between open-volume defects and Cu precipitates was revealed clearly by the view point of S-W relationship. The S-W interaction for the different CumVn complexes was also calculated theoretically by MIKA-Doppler, which supports our experimental observations qualitatively. The results indicate that open-volume defects were formed first after cold rolling, followed by the Cu precipitation and recovery of open-volume defects, Cu precipitates recovered at the end. It is interesting that the trajectory of (S, W) points with increasing annealing temperature formed a similar closed “Parallelogram” shape. It is benefit for revealing the behavior of Cu thermal precipitation and their evolution in various Cu-bearing steels under thermal treatment. In addition, we also investigated the Cu content effect on the Cu precipitation in FeCu alloys, and the Cu precipitate phenomenon was enhanced in higher Cu content alloys.

Investigation of Heat Resistance of Al-Ni Layered Coating

The effect of isothermal annealing at 1100°C on the kinetics of phase transitions in the coatings system Ni-Al, obtained by the complex technology, is studied. The cyclic heat resistance of the coating is investigated at 1100°C.

Effect of isothermal annealing on Spheroidization of carbides in GCr15 steel

The spheroidizing effect of GCr15 steel was studied and the microstructure was analyzed by SEM under different isothermal annealing. The results show that: the carbide particles become smaller and smaller which is easy to form and grow into lamellar carbide with the increase of the temperature, and when the heating temperature is increased to 800°C; The carbide particles can grow into spherical shape independently, and even some of the particles begin to grow up with the increasing of the heating time; The optimum process of GCr15 steel is heating temperature 780 °C, heating time 5h, isothermal temperature of 700 °C, isothermal time 3h.

Effects of isothermal annealing on the oxidation behavior, mechanical and thermal properties of AlN ceramics

Abstract To evaluate the oxidation behavior of AlN ceramics prepared using a pressureless sintering method, aluminum nitride bulk samples were annealed at temperatures ranging from 900 °C to 1300 °C for 1–5 h under an air atmosphere. The phase composition, microstructure and weight change of the oxidized samples were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis-mass spectrometry (TGA-MS), respectively. The results showed that certain of the gaseous oxidation products of AlN ceramics were nitrogen oxides (NO x ). The oxidation reaction started at approximately 800 °C to 900 °C. The thermal conductivity and flexural strength of AlN ceramics were enhanced slightly after the heat treatment in the 900–1100 °C temperature range. The entire surface of the AlN block was covered with a thin, compact alumina layer after oxidizing at 1100 °C for 3 h, which may enhance the metal adhesion to the AlN surface in a metallization process. At 1200 °C and higher, the AlN ceramics oxide layer became rough, porous, and cracked, leading to a sharp drop in the flexural strength and thermal conductivity of the AlN ceramics.

The Effect of Isothermal Annealing on the Structural and Magnetic Properties of the Bulk Amorphous Alloy: FeCoTiYB

The aim of this paper was to conduct studies concerning the magnetization of bulk amorphous Fe61Co10Ti4Y5B20 alloy when subjected to strong magnetic felds in the area known as the approach to ferromagnetic saturation. The samples were produced using the suction-casting method. The amorphicity of the investigated alloy, in the as-quenched state and after annealing process in a temperature below the crystallization temperature was verified using X-ray diffractometry. The magnetization was measured using a vibrating sample magnetometer. On the basis of the obtained results, the type of structural defects having influence on magnetization in high magnetic fields were determined. Analysis of the high-field magnetization curves has facilitated the calculation of the spin wave stiffness parameter. From this parameter, the range and strength of the exchange interactions could be determined.

Combined effect of isothermal annealing and pre-compression on mechanical properties of Cu36Zr48Al8Ag8 bulk metallic glass

The combined effects of isothermal annealing and pre-compression on the mechanical properties of Cu36Zr48Al8Ag8 bulk metallic glass (BMG) were investigated. The as-cast specimens were first annealed at 743 K for 10 min, and then pre-compressed under 800 MPa for 1, 3, 5 and 10 h, respectively. The results indicated that annealing resulted in the formation of nanocrystals with a diameter of ~10 nm in the amorphous matrix and a drastic decrease of the free volume, leading to complete loss of the plasticity of the BMG. Applying pre-compression under a stress of 800 MPa for a proper duration (5 h) resumed part of the lost free volume in the BMG matrix and therefore partially recovered the plasticity. A very long period of pre-compression (10 h) decreased the free volume again, which was caused by the excessive crystal growth.

Crystallization and hardening of Zr-40at.% Cu thin film metallic glass: Effects of isothermal annealing

Abstract Effects of isothermal annealing on structural relaxation, crystallization and mechanical behavior of Zr-40 at.% Cu thin film metallic glass (TFMG) are reported. Two annealing temperatures have been chosen in the supercooled liquid region (ΔT) and one below the glass transition temperature (Tg). During annealing the free volume decreased and nanocrystals nucleated into the matrix. Results show that the nanocrystalline CuZr2 intermetallic phase precipitates in the glassy matrix with respect to the annealing temperature and duration. When annealed below Tg, the structural relaxation induces a slight improvement of the mechanical properties with a hardness and Young's modulus variation of about 2.5% and 9.0% compared with the as-deposited values. At higher temperatures, it is shown that hardness increases of about 5.5% and 25.0% after a heat treatment of 60 min at 350 °C and 380 °C, respectively. The elastic modulus follows a time dependent increase from ~ 100 GPa (as-deposited) up to ~ 105 GPa after a one-hour annealing at 350 °C and ~ 125 GPa at 380 °C, respectively.

An investigation into the effect of isothermal annealing on the structure (XRD), microstructure (SEM, TEM) and magnetic properties of amorphous ribbons and bulk amorphous plates

Abstract Test samples of the alloy Fe61Co10Y8W1B20 were fabricated in the form of both amorphous ribbons and bulk amor-phous plates. The structure, microstructure and magnetic properties of samples in the as-quenched state and after annealing were investigated. The aim of the paper is to show the effect of the thermal treatment on the structural changes occurring in the amorphous state. The thermal treatment, performed at well below the crystallisation temperature, did not cause crystallisation. In the investigated amorphous alloys it has been found that, after a specific thermal treatment, structural relaxation occurs in the presence of structural defects, such as quasidislocational dipoles. Also, supporting the microscopy investigations with measurements of the magnetic properties can be extremely beneficial for facilitating description of the real structure and properties of the amorphous alloys; further, this testing combination offers the possibility for designing the optimal application parameters for an alloy.

Effect of Isothermal Annealing on Microstructural Morphology of Martensite in a Super-Martensitic Stainless Steel Subjected to Different Prior Conditions

A super-martensitic stainless steel of the Fe–Cr–Ni family was investigated for morphological changes during isothermal annealing after subjecting it to different prior conditions. The key issues during thermomechanical treatment included determination of conditions for austenite stability and reversibility and deciding the appropriate prior treatments for the cold worked alloy before subjecting it to isothermal annealing. The study evaluated the effect of isothermal annealing on the recrystallization kinetics, phase reversion, and microstructural changes in the alloy. Intercritical isothermal annealing was carried out on samples in the range 750–900 °C for short time periods in the range of 1–2.5 min. The recrystallization behavior and microstructural changes were studied by electron backscatter diffraction, X-ray diffraction, and Vickers's hardness measurements. Martensite morphology showed significant changes during the isothermal annealing process with dependence on prior matrix substrate. The tensile properties were also evaluated. The cold rolled (CR) and isothermally annealed samples provided an improved combination of strength and ductility at the optimum heat treatment parameters.