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We studied the effect of isothermal annealing (600–750 °C, 1 to 1000 min) on the microstructure and mechanical properties of SAF 2205 duplex stainless steel. Impact toughness was found to be significantly more affected than hardness by annealing. Annealing at 750 °C for 1000 min resulted in a more than 90% decrease in impact toughness, while hardness only increased by 25%. Tensile strength increased up to 100 MPa, but elongation decreased by more than 50% under the same conditions. Sigma phase formation was minimal at lower temperatures (650 °C and below) but increased significantly at higher temperatures. At 750 °C and 1000 min of annealing, the ferrite content dropped from 50% to 16%. These findings suggest that annealing temperature and time need to be carefully controlled to avoid a reduction in impact toughness and ductility caused by sigma phase precipitation. The harmful effect of sigma phase precipitation on mechanical properties was directly shown. [ABSTRACT FROM AUTHOR]

We studied the effect of isothermal annealing (600–750 °C, 1 to 1000 min) on the microstructure and mechanical properties of SAF 2205 duplex stainless steel. Impact toughness was found to be significantly more affected than hardness by annealing. Annealing at 750 °C for 1000 min resulted in a more than 90% decrease in impact toughness, while hardness only increased by 25%. Tensile strength increased up to 100 MPa, but elongation decreased by more than 50% under the same conditions. Sigma phase formation was minimal at lower temperatures (650 °C and below) but increased significantly at higher temperatures. At 750 °C and 1000 min of annealing, the ferrite content dropped from 50% to 16%. These findings suggest that annealing temperature and time need to be carefully controlled to avoid a reduction in impact toughness and ductility caused by sigma phase precipitation. The harmful effect of sigma phase precipitation on mechanical properties was directly shown.

Gadolinium‒aluminum‒gallium garnet crystals are grown with charge compositions Gd3AlxGa5– xO12 (x = 1–3) and Gd3Al2Ga3O12:Ce3+. The effect high-temperature annealing in air has on the optical properties of these crystals is established. It is shown that annealing does not affect the state of cerium oxidation. X-ray fluorescence reveals a deficiency of gallium in all the investigated crystals. [ABSTRACT FROM AUTHOR]

To investigate the residual stress relaxation behaviors and fatigue strength, EA4T steel specimens are subjected to micro-shot peening (MSP), and part of them are isothermally annealed at 250 °C for 2 hours. Fatigue experiments are conducted on a four-point rotating bending machine under constant and variable loads. Surface compressive residual stress (CRS) and full width at half maximum (FWHM) before the experiment and during fatigue loading are analyzed using the x-ray diffraction method. The results indicate that the CRS of the MSP specimens are relaxed after the isothermal annealing, leading to a decrease in their fatigue strengths. Variable loading slightly increased the fatigue life of the un-peened specimen, but significantly reduced that of the MSP specimens. The effect of CRS relaxation on fatigue strength is analyzed, and the relationship between CRS and FWHM is also discussed. [ABSTRACT FROM AUTHOR]

The effect of post-growth isothermal annealing in vacuum and in air on the optical properties of Ca3TaGa3Si2O14 crystal samples of Z- and X-cuts is studied. The spectral dependences of the transmission coefficients are measured in the wavelength range (240–700) nm taking into account anisotropy and dichroism. On the Z-cut samples in the initial state an absorption band at λ = 360 nm in the ultraviolet range is observed; in the visible region, there are two absorption bands at λ = 460 nm and λ = 605 nm. Additionally, a band at λ = 290 nm is observed on the X-cut samples. When the sample is rotated around the direction of the light beam by 90 degrees, a change in the intensity of the absorption bands is observed. Annealing in vacuum leads to a decrease in the intensity of the absorption bands in the near ultraviolet and visible range, except for the absorption band at λ = 605 nm. Annealing in air leads to the opposite effect, i.e., an increase in the intensity of the absorption bands, except for the band λ = 605 nm. The value of the anomalous birefringence of the samples was estimated by the Mallard method. The degree of linear dichroism is calculated. It is shown that the degree of dichroism decreases as a result of annealing in vacuum and increases during annealing in air. [ABSTRACT FROM AUTHOR]

The effect of irradiation with a pulsed electron beam on the diffusion of titanium in the polycrystalline Zr-1 wt.% Nb alloy is studied using high-frequency glow discharge optical emission spectrometry. The depth distribution profiles of titanium concentration in the Zr-1 wt.% Nb alloy after isothermal diffusion annealing and annealing under surface irradiation with a pulsed electron beam are determined. It is shown that under simultaneous exposure to temperature and irradiation with a pulsed electron beam, an increase in the coefficient and a decrease in the activation energy of grain boundary diffusion are observed in the near-surface layer of the alloy. [ABSTRACT FROM AUTHOR]

The (Fe82Al13.5Ga4.5)99.9(NbC)0.1 sheets with strong Goss texture and large magnetostriction were prepared by rolling and isothermal annealing processes. Single Goss grain growth was observed in sheets undergoing isothermal annealing at 1050 °C for 1 h using Ar as protecting gas. With annealing time increasing to 8 h at 1050 °C, a largest magnetostriction of 154 × 10−6 is obtained in sheet and a large λ// (the maximum magnetostriction with magnetic field parallel to rolling direction) of 160 × 10−6 along the rolling direction is also observed. The fact that a λ// of 160 × 10−6 along RD can be achieved with only 4.5 at% Ga in the Fe-18 at% (Al, Ga) sheet is of practical importance. Compared with previous studies in Fe–Al and Fe–Ga sheets, this paper provides a more efficient approach to prepare strong Goss textured sheets. In this way, a slow continuous heating process, sulfur-induced surface energy control and high-temperature annealing above 1200 °C are no more necessary. It shows a good prospect for industrial production of high-performance magnetostrictive alloy sheets. [ABSTRACT FROM AUTHOR]

Due to the excellent mechanical properties, TiZrNb-based refractory high entropy alloys (RHEAs) show great potential application prospects in aviation, aircraft and petrochemical. However, the RHEAs are usually thermally metastable and brittle phases can be precipitated in intermediate temperature (such as 500–700℃), which severely limit the preparation of large-sized RHEAs ingots in industrial production. In this paper, we propose an alloy optimization strategy to suppress the precipitation of TiZrNb-based RHEAs by adding interstitial atomic oxygen (O). The results show that the precipitation temperature region of brittle phases can be reduced from 500°C∼650°C to 550°C∼600°C after adding oxygen, and the temperature region is reduced by more than 66 %. Moreover, the growth rate of precipitated phase decrease from 4.1 × 10−23 m3/s to 1.9 × 10−24 m3/s after adding oxygen, which is reduced by more than ten times. The analysis shows that adding oxygen inhibits the diffusion rate of Zr at intermediate temperature, thus delaying the formation of Zr-rich phase. Based on this, TiZrNb-based RHEAs with oxygen can well keep the outstanding ductility even after annealing at intermediate temperature for 4 hours, while the TiZrNb-based RHEAs without oxygen show ∼50 % ductility loss after the same annealing treatment. Our results not only provide new insights into the phase stability and mechanical stability of RHEAs, but also provide a new strategy for improving the phase stability of large-size ingots for engineering applications. • Adding oxygen significantly inhibited the phase precipitation at intermediate temperature. • Adding oxygen reduces the principal element diffusion rate and thus inhibits the phase precipitation. • Adding oxygen avoids the sharp deterioration of ductility after isothermal annealing. [ABSTRACT FROM AUTHOR]

Production processes of hot forging most often look similar [1-3]. Forging in several operations, usually in three or four. Most often the first operation is upsetting or flattening (sometimes rolling). The last operation is finishing forging. This applies to the production of steel forgings for the automotive, agricultural and other similar industries. Typical production proceeds as follows: the forgings are cleaned (shot-blasted) and then heat treatment is performed. It can be normalization, hardening and tempering, etc. After the heat treatment, forgings are checked and subjected to strength and microscopic tests, hardness tests, impact tests. The type of tests depends on the recipient. The process described in the work takes place in three operations. The heat treatment used so far is hardening and tempering. An attempt was made to change the heat treatment technology for a selected product made of 42CrMo4 steel (1.7225) (4140). An isothermal annealing test was carried out at different temperatures and for different times. The possibility of using heat from the forging process in heat treatment processes for the described product has been confirmed.

The investigation was performed on pure sintered (PM) copper and dilute PM copper-based alloys with 3 and 5.9 wt.% of platinum. Investigated PM samples were obtained using the standard powder metallurgy technique by mixing the elemental powders in proper ratio followed by pressing in hydraulic press and sintering in a hydrogen atmosphere. The PM samples were further cold deformed by rolling at ambient temperature to a total rolling reduction of 60 %. On pre-deformed samples, the low-temperature isothermal annealing up to the 100 hours was accomplished. During all stages of isothermal annealing, the values of Vickers hardness, micro-hardness, and electrical conductivity were measured. Also, the microstructure was analyzed using the scanning electron microscopy (SEM). This investigation has shown a slight increase in all measured properties for both dilute Cu-Pt alloys. An increase in mechanical properties was some more pronounced for more alloyed Cu-5.9wt%Pt alloy. During the low-temperature isothermal annealing, there were no significant changes in properties for pure pre-deformed copper.

Bulk amorphous alloys, as a material with broad application prospects, are highly expected in many cutting-edge applications. However, its plastic deformation relies on highly localized shear bands, resulting in brittle fracture characteristics of materials with low plastic strain as a whole. Therefore, strengthening and toughening of amorphous alloys is one of the key topics in the research of amorphous applications. In this paper, the effects of different isothermal annealing temperature on the microstructure and uniaxial compression properties of Cu _45 Zr _45 Ag _7 Al _3 amorphous alloy were studied by means of differential scanning calorimetry (DSC), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that Cu _10 Zr _7 , AlCu _2 Zr, Cu _8 Zr _3 and Al _2 Zr phases precipitated successively from the amorphous alloy matrix with the increase of annealing temperature, and the fracture strength and plastic strain increased first and then decreased; At an isothermal annealing temperature of 741 K, the precipitated nanocrystalline Cu _10 Zr _7 phase can improve the fracture strength of the alloy; when the annealing temperature rises to 746 K, the strength of the alloy decreases slightly, but the plasticity increases; with the continuous increase of annealing temperature, the plasticity of the alloy decreases and the strength continues to increase; As the annealing temperature continues to increase, the fracture strength of the alloy decreases, exhibiting significant brittle fracture characteristics.

The laws of the change in the electrophysical properties of the C87 – 2, C78 – 4, C78 – 5 glasses, used in electronic optics are studied. A comparative analysis of the effect of the transmitted electric current on the formation of a new phase and the time to achieve the phase equilibrium in glasses is carried out. It was established that annealing leads to an equilibrium state, stabilizes the structure, and also reduces the electrical conductivity of the glass.

The effects of minor alloying addition of Cu on the glass-forming ability and crystallization process of Fe71.7−xB16.7Si8.3Zr3.3Cux and Fe72.5−xB16.7Si8.3Hf2.5Cux (x = 0, 0.3, 0.7, 1.0 and 1.3; at%) alloys were investigated. It was found that the critical glass formation size of rod samples gradually decreased from 2.5 to 1 mm with increasing Cu content in these alloys. Single α-Fe phase nanocrystalline alloys were obtained after isothermal annealing the Fe–B–Si–Zr/Hf–Cu glassy alloys containing 0.7–1.0 at% Cu. The Fe71B16.7Si8.3Zr3.3Cu0.7 alloy exhibited good soft magnetic properties with a high saturation magnetization (~ 1.22 T) and a low coercive force (~ 0.6 A/m) after annealing at 853 K for 10 min due to the precipitation of α-Fe nanoparticles of 8 nm size in the glassy matrix. The structural evolution on annealing and the variation tendencies against Cu content of the glass transition temperature, thermal stability and glass-forming ability of the Fe–B–Si–Zr/Hf–Cu amorphous alloys were discussed using a dual-cluster local structure model. [ABSTRACT FROM AUTHOR]

[Display omitted] • 304L stainless steels with 1 and 4 wt% Hf additions were nanostructured by MA. • The in-situ XRD investigations revealed a sluggish diffusion by Hf addition. • The annealing of nanocrystalline 304L yielded grain growth to 960 nm at 900 °C. • In-situ formed HfO 2 oxides formed with Hf additions stabilized the microstructure. • 195 HV hardness of 304L annealed at 1100 °C increased to 329 HV with Hf addition. 304L stainless steels with Hf additions were nanostructured by mechanical alloying (MA) and annealed at temperatures up to 1100 °C. The results showed that face-centered cubic (fcc) phase in 304L transformed to body-centered cubic (bcc) phase during MA. The in-situ studies revealed that bcc-to-fcc phase transformation completed after 105 min annealing at 900 °C for 304L, whereas Hf addition increased the required time and temperature for the complete transformation. The grain size of 304L stainless steel was ~10 nm after MA and remained ~167 and ~293 nm after annealing at 900 and 1100 °C, respectively, with Hf addition in comparison to 960 nm average grain size of base 304L stainless steel after annealing at 900 °C. The hardness of 304L increased from ~200 HV to 408 HV after MA and remained 329 HV after annealing at 1100 °C with Hf addition as opposed to 195 HV hardness of 304L. [ABSTRACT FROM AUTHOR]

Subject of research – process of the solution of a task on change of duration of the incubatory periods for phases which have to appear in a diffusive zone after the component layer with a smaller temperature of melting is exhausted, topic – identifi cation of features of calculation of parameters of diffusion in two-component multiphase systems at “limited” intake of this component, the purpose ― to offer a way of the solution of a task on change of duration duration of the incubatory periods for phases which have to appear in a diffusive zone after the component layer with a smaller temperature of melting is exhausted. Methods and methodology. Chemical and thermal methods of processing, in particular, method of diamond turning; a method of the smallest squares in a method of calculation of parameters of diffusion in two-component multiphase system. Results. The method of calculation of parameters of diffusion in two-component multiphase systems at “limited” intake of a component with a smaller temperature of melting is offered. The dependence of thickness of a layer of this component in two-component multiphase system is constructed. Dynamics of growth of phases in this system from diffusion time is investigated. The dependence of the incubatory period of appearance of the subsequent phases from layer thickness of component with a smaller temperature of melting in two-component multiphase system. The example of the practical solution of a task on change of duration of the incubatory periods for phases in the coppergallium system is given which have to appear in a diffusive zone after the component layer with a smaller temperature of melting is exhausted. Conclusions. It is shown that in two-component multiphase system for each subsequent new phase there is a critical value of thickness of a layer of a component with a smaller temperature of melting. At a thickness, smaller critical value, a certain duration of process of annealing causes change of the incubatory period of these phases regardless of the fact that preceded it: component exhaustion with a smaller temperature of melting or dissolution of one of the previous phases.

The results of a study of the electrical conductivity and diffusion of potassium ions in borate-barium glass (C78–5) – 2,2% SiO2 57,8% B2O3 8,2% K2O 19,0% BaO 3,5% CaO 8,8% Al2O3 0,5% MgO with the passage of electric current through the sample. The time dependences of self-diffusion coefficients are calculated for the transmission of an electric current at a constant temperature.

The article discusses the results of investigations performed during a thermo-mechanical treatment of forgings made of chromium‑molybdenum 42CrMo4 grade steel. The treatment was realized during a regular series production. The forging process was combined with a heat treatment carried out directly after forging on a specially adapted station. Such a production technology will make it possible to eliminate the step of repeated heating of the forgings. On the example of an element of a steering gear, it was demonstrated how it is possible to perform an isothermal annealing process starting from the temperature at which the trimming of the forgings ends. During the cooling of the forgings, it is enough to maintain the temperature at the proper level in order for the exothermal phase transformation of austenite into pearlite to take place. The test results show that, with the properly selected temperature of isothermal annealing, it is possible to obtain an equilibrial ferritic-pearlitic structure in the required hardness scope. Introducing such a solution into the industrial practice would allow savings more than 80% of the energy used for the heat treatment of forging in this case.

At present, Nb3Sn superconductors are becoming more popular in high magnetic fields. The growth law of Nb3Sn phase in a planar CuSn/Nb diffusion couple has been studied, whereas the formation mechanism of Nb3Sn phase in a cylindrical CuSn/Nb diffusion couple is still controversial. The purpose of this work is to investigate the growth exponent of Nb3Sn phase at the initial stage of annealing by use of scanning electron microscopy (SEM) through which the thickness of Nb3Sn layer can be obtained. In this study, bronze-processed Nb3Sn multifilamentary wires with different annealing time were investigated. The Nb3Sn phase was formed during isothermal annealing at 670 °C by solid-state diffusion, which was accomplished by the movement of Sn atoms from the CuSn/Nb3Sn interface to Nb3Sn/Nb interface. However, the formation mechanism of Nb3Sn phase at the initial stage of annealing is still not well understood. Microstructural evolution of Nb3Sn phase during isothermal annealing was studied by SEM. The mean thickness of the Nb3Sn layer ( Δ x Nb 3 Sn ) is expressed as a power function of the annealing time (t) by the equation Δ x Nb 3 Sn 2 = k (t / t 0) n , where t0 is the unit time, k is the reaction rate constant and n is the growth exponent. The growth exponent has the average value of 0.82, which means that the formation of the Nb3Sn phase is both governed by the interface reaction and the grain boundary diffusion. [ABSTRACT FROM AUTHOR]

Polydioxanone (PPDO) is synthesized by ring-opening polymerization of p-dioxanone, using stannous octoate as the catalyst. The polarized optical micrograph (POM) shows thes pherulite growth rate of PPDO decreases with an increase in the isothermal crystallization temperature. PPDO is compression-molded into bars, and PPDO bars are subjected to isothermal annealing at a range of temperatures (Ta = 50, 60, 70, 80, 90, and 100 °C), and correspond to three different annealing times (ta = 1h, 2h, 3h). The effect on PPDO is investigated by using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). With an increase in Ta and ta, the grain size and the degree of crystallinity also increase. Meanwhile, the tensile strength is significantly improved. The PPDO bars (90 °C, 2 h) reach the maximum crystallinity (57.21%) and the maximum tensile strength (41.1 MPa). Interestingly, the heat treatment process does not result in serious thermal degradation. It is observed that the hydrolytic degradation of the annealed PPDO is delayed to some extent. Thus, annealed PPDO might have potential applications, particularly in the fields of orthopedic fixation and tissue engineering. [ABSTRACT FROM AUTHOR]

The influence of the isothermal annealing conditions in air (at 560 and 625°C for 1000 h) on the deformation behavior of a high-temperature VT18U titanium alloy under tension is studied. The plasticity of the alloy at room temperature decreases from 14 to ≈5% after annealing at the investigated temperatures. The thickness of the gas-saturated layer is 17 and 42 μm after annealing at 560 and 625°C, respectively. The main factor determining the plasticity of the alloy in the oxidized state is the oxygen content gradient in the gas-saturated layer. [ABSTRACT FROM AUTHOR]

Production processes of hot forging most often look similar [1-3]. Forging in several operations, usually in three or four. Most often the first operation is upsetting or flattening (sometimes rolling). The last operation is finishing forging. This applies to the production of steel forgings for the automotive, agricultural and other similar industries. Typical production proceeds as follows: the forgings are cleaned (shot-blasted) and then heat treatment is performed. It can be normalization, hardening and tempering, etc. After the heat treatment, forgings are checked and subjected to strength and microscopic tests, hardness tests, impact tests. The type of tests depends on the recipient. The process described in the work takes place in three operations. The heat treatment used so far is hardening and tempering. An attempt was made to change the heat treatment technology for a selected product made of 42CrMo4 steel (1.7225) (4140). An isothermal annealing test was carried out at different temperatures and for different times. The possibility of using heat from the forging process in heat treatment processes for the described product has been confirmed. [ABSTRACT FROM AUTHOR]

The results of investigation of processes occurring under heating and in isothermal conditions during the passage of electric current through borate-barium glass С78 — 5, applied in electronic engineering, are presented. Experimental data have been used to determine the dependence of the specific electric conductivity on the temperature and on the annealing time for a continuous unidirectional current through the sample, and also for a symmetric alternating current excluding electromass transfer.

This manuscript reports the isothermal annealing effect on the mechanical and microstructure characteristics of Sn-0.7Cu-1.5Bi solder joints. A detailed microstructure observation was carried out, including measuring the activation energy of the intermetallic compound (IMC) layer of the solder joints. Additionally, the synchrotron µX-ray fluorescence (XRF) method was adopted to precisely explore the elemental distribution in the joints. Results indicated that the Cu6Sn5 and Cu3Sn intermetallic layers thickness at the solder/Cu interface rises with annealing time at a rate of 0.042 µm/h for Sn-0.7Cu and 0.037 µm/h for Sn-0.7Cu-1.5Bi. The IMC growth’s activation energy during annealing is 48.96 kJ mol-1 for Sn-0.7Cu, while adding Bi into Sn-0.7Cu solder increased the activation energy to 55.76 kJ mol−1. The µ-XRF shows a lower Cu concentration level in Sn-0.7Cu-1.5Bi, where the Bi element was well dispersed in the β-Sn area as a result of the solid solution mechanism. The shape of the IMC layer also reconstructs from a scallop shape to a planar shape after the annealing process. The Sn-0.7Cu hardness and shear strength increased significantly with 1.5 wt.% Bi addition in reflowed and after isothermal annealing conditions.

Samples of four types of low-dropout voltage regulators, with both serial pnp and npn transistors, were examined in room-temperature isothermal gamma radiation annealing. After uninterrupted exposure to a total ionising dose of 500 Gy, biased and loaded voltage regulators were examined in room-temperature annealing within the first 30 minutes after the exposure. Beside the on-line measurement of output voltage and quiescent current during the thirty-minute period immediately after irradiation, also results were procured after 10-year room-temperature spontaneous recovery. Data obtained during the irradiation and rapid annealing were fitted with linear, exponential, and power-law regression functions. A simple procedure was proposed, based on the quiescent current annealing factor, for the quick estimation of the integrated voltage regulator's radiation sensitivity during the post-irradiation isothermal annealing. In order to estimate the circuit's radiation sensitivity, immediately after irradiation, tested devices have to be left in the same operating conditions as during the exposure. If a clear trend of the quiescent current recovery can be observed, further examinations have to be implemented to estimate if a circuit is acceptably radiation-tolerant. If no recovery trend can be observed within the first hour after irradiation, or even further degradation is noticed, then the examined voltage regulator is a radiation-sensitive device and cannot be used in radiation environments. The described procedure is based on the macroscopic effects of the radiation-induced charge-trapping in field oxides and interfaces. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 171007: Physical and functional effects of the interaction of radiation with electrical and biological systems]

Relevance of the work: Modern science and technology show interest to use of low-dimensional and nanodimensional materials based on carbon. One of the most prospective materials for synthesis of similar structures is poly (vinylidene fluoride). The same amount of fluorine and hydrogen in polymeric chains of this material allows achieving high extent of its dehydrofluorination by elimination of HF molecules. At gradual penetration of dehydrofluorinating chemical reagents in depth of a poly (vinylidene fluoride) film, carbon heterolayers are formed on its surface. They differ in residual fluorine content and electric conductivity. Such heterostructures with flexible polymeric basis substrate can be demanded by modern microelectronics. Therefore study of their physical and chemical properties seems to be urgent. The main aim of the research is to study the effect of isothermal annealing duration at 250 °C on magnetic and structural characteristics of poly (vinylidene fluoride) samples partially dehydrofluorinated via a chemical way. The methods used in the study: ESR-spectroscopy, differential thermal analysis, thermogravimetric and differential thermogravimetric analysis, X-ray diffraction. The results: The authors have developed the method for producing a new magnetically active carbon material on a poly (vinylidene fluoride) film surface. The parameters of ESR spectra of poly (vinylidene fluoride) samples partially dehydrofluorinated via a chemical way were measured. The samples were subjected to subsequent heat treatment at 250 °C with various duration of isothermal annealing. Based on the data of differential thermal analysis the assumptions are drawn on possible mechanism of regular elevation in paramagnetic centers content at increase in time of isothermal annealing.

This work highlights the relationship between the preparation, crystallization behavior, microstructures, and mechanical properties of Cu-based bulk metallic glasses (BMGs) and their composites (BMGCs). (Cu47Zr45Al8)97.5Y1.5Nb in-situ BMGCs were prepared using isothermal annealing, and the experimental results indicate tunable mechanical properties of the alloys by processing parameter manipulation. The crystallinity of (Cu47Zr45Al8)97.5Y1.5Nb BMGCs increases with extended annealing temperature and time, while their phase transition with rising temperature follows Am (amorphous state) → Am + Cu10Zr7 →Am + Cu10Zr7 + AlCu2Zr + Al2Zr. Precipitation strengthening during annealing above 720 K (447 ºC) can enhance the alloy microhardness remarkably and achieve an optimum of 712 HV by annealing at 800 K (527 ºC) for 60 min. TEM results show that Cu10Zr7 with sizes of 12~15 nm precipitates out upon crystallization and thereby accounts for the superior compressive property. The alloy exhibits a fracture strength up to 2080 MPa after annealing at 680 K (407 ºC) for 30 min. Morphological observation of the fracture surface reveals a transition of fracture characteristics from the typical amorphous ductile manner to a brittle manner with further annealing. The investigation provides novel thoughts of BMGs processing for further performance improvement.

Abstract Isothermal annealing can enhance the soft magnetic properties of Fe-based metallic glasses, but usually causes brittleness. In this work, we studied the relaxation kinetics of Fe-based metallic glasses below glass transition temperature and the evolution of soft magnetic properties and plasticity. We found that the metallic glass first experiences secondary (β) relaxation and then transforms into primary (α) relaxation upon isothermal annealing. The magnetic properties are enhanced predominantly during β relaxation stage but don't change very much during α relaxation stage. The plasticity doesn't change very much during β relaxation stage but gets deteriorated during α relaxation stage. The structural origin of the changes is also studied. These results prove that it is probable to achieve metallic glasses with both excellent soft magnetic properties and excellent mechanical properties by controlling the relaxation process, which may provide a universal protocol for enhancing the functional performance of soft magnetic metallic glasses. Highlights • A new approach is found to achieve superior soft magnetism combined with good plasticity by controlling the relaxation process. • Metallic glasses first experience secondary (β) relaxation and then primary (α) relaxation upon isothermal annealing. • The influence of different relaxation modes on the properties of Fe-based metallic glass was investigated experimentally. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Amorphous Fe 60 Cr 15 Mn 10 N 15 powder with a large supercooled liquid region was prepared by mechanical alloying. • The amorphous phase formation mechanism was determined via the theoretically thermodynamic calculation. • The powder both undergoing mechanical alloying process and the annealing possesses good soft magnetic properties. Abstract In this paper, the amorphous phase formation process, formation mechanism and magnetic properties, during the mechanical alloying (MA), have been investigated in Fe 60 Cr 15 Mn 10 N 15 alloy, respectively. The results obviously indicate that amorphous Fe 60 Cr 15 Mn 10 N 15 with a wide supercooled liquid region (SCLR, 82 K) can be obtained via 40 h MA process. With the milling time increasing gradually, the microstructures evolve from the initial crystalline powder, to completely amorphous phase, and eventually to amorphous phase with embedded Cr 2 N. By calculation, the mixing chemical enthalpy Δ Hchem and amorphous formation enthalpy Δ Hform have been obtained as −0.24 kJ/mol and −6.610 kJ/mol, respectively, implying the existence of thermodynamic advantage for the amorphous phase formation. In addition, the effect of 7 at% B and 7 at% Mo addition on the amorphous phase formation have also been studied, however, the diffraction peaks corresponding to Mo (Cr 2 N) still appear after 120 h milling. Meanwhile, isothermal annealing experiments were conducted at different temperatures, obtaining the microstructure evolution as: amorphous → amorphous alloy + Cr 2 N → α-Fe + Cr 2 N → α-Fe + CrN + Cr 2 N. And the hysteresis loops in amorphous Fe 60 Cr 15 Mn 10 N 15 undergoing both the MA process and isothermal annealing procedure provide us with the evidence that this alloy system can exhibit excellent soft magnetic properties. [ABSTRACT FROM AUTHOR]

The evolution of microstructure, thermal stability, mechanical response behavior and tribological properties of the Ti 20 Zr 20 Cu 20 Hf 20 Be 20 high entropy bulk metallic glass (HE-BMG) before and after isothermal annealing were systematically studied. The results demonstrate that isothermal annealing affects the mechanical and tribological properties by modifying the microstructure and the consumption of free volume in the structure. Although the strength/hardness of HE-BMG can be improved after the isothermal annealing before crystallization, the deterioration of shear plastic deformation leads to serious brittle fracture, thus cancelling out the contribution of strength to wear resistance and resulting in negligible variation of wear rates. When the crystallization isothermal annealing is performed, the wear resistance can be dramatically enhanced and the wear mechanism changes to slight abrasive and oxidation wear, which can be mainly attributed to the good co-deformation between the amorphous matrix and precipitated crystalline phases. • An amorphous phase separation is discovered during isothermal annealing in a HE-BMG. • The largescale phase separation causes improved hardness, but deteriorated plasticity. • Composite structure is gained by isothermal crystallization annealing in a HE-BMG. • The composite structure can optimize the mechanical properties and wear resistance. [ABSTRACT FROM AUTHOR]

Under standard conditions, DSS (duplex stainless steel) features differing amounts of ferrite and austenite, essentially depending on the thermal treatment performed. This study is focused on the ultrasonic tests (UTs) response of DSS 2205, as a function of the microstructure, in terms of austenite volume fraction and austenitic grains evolution owing to different soaking times at 1050 °C. UTs were carried out on several samples. The samples underwent varying thermal treatments characterized by a constant maintenance temperature with different soaking times that allowed for microstructure evolution and modification of the structural constituents’ fraction. The UTs have highlighted an attenuation trend with the response mainly dependent upon the wave scattering and energy absorption caused by the grain features. In particular, the peak of sound attenuation was shown to correspond with the microstructure, which featured a major amount of austenite (in terms of volume fraction and the grain dimensions) and the disappearance of austenitic precipitates within the ferritic matrix. In order to obtain less UT attenuation, without affecting the mechanical and corrosion properties, the soaking should last as little time as possible.

The paper presents the results of research on the structure and magnetic properties of Fe61+xCo10−xW1Y8B20 alloys (where x = 0, 1 or 2). The alloys were produced using two production methods with similar cooling rates: Injection casting and suction casting. The alloy samples produced were subjected to isothermal annealing at 940 K for 10 min. The structure of the materials was examined using X-ray diffraction. Isothermal annealing has led to the formation of various crystallization products depending on the chemical composition of the alloy and the structure of the alloy in a solidified state. In two cases, the product of crystallization was the hard magnetic phase Y2Fe14B. However, the mechanism of this phase formation was different in both cases. The magnetic properties of alloys were tested using a vibrating sample magnetometer and a Faraday magnetic balance. It is found that the grain crystallite size of the crystalline phases have a decisive influence on the value of the coercive field (especially in the case of hard magnetic phases). It has been shown that privileged areas can already be created during the production process. Their presence determines the crystallization process.

The regularities of changes in the electrical properties of glasses S87-2,S78-4,S78-5 used in vacuum electronics. A correlation between structural change and electrical conductivity is proposed. A comparative analysis was carried out of the influence of an electric current on the formation of a new phase and the time to reach the phase equilibrium in the glass.

In this study, the effect of mechanical alloying on the microstructure and phase constituents of Mg-6Al-1Zn-1Si system was investigated. To understand the thermal behavior, isothermal annealing was performed at three different temperatures of 350, 400 and 450 °C for 1h. The results showed the grain size initially decreases with increasing the milling time up to 35h and then slightly increases. In contrast, the lattice strain increases sharply with increasing the milling time up to 35h and then decreases. Second-phase intermetallic particle Mg2Si was produced during annealing and the amount of this phase was increased with increasing annealing temperature. The mechanical alloying process decreased the formation temperature of Mg2Si.

Amorphous chalcogenide composition AS4Se3Te3 is prepared by conventional quenching technique. The separate annealing or γ quanta irradiation not effect on the dc conductivity properties of the prepared composition. When the prepared samples are subjected to simultaneous annealing at temperature 413 K and γ quanta irradiation the dc conductivity increases. The dark dc conductivity increases by increasing the time of exposure to γ irradiation. At irradiation dose 1.47 × 104 Gy the dc conductivity starts to have metallic like conductivity character. These samples could be used as high temperature γ quanta dosimeter. By applying scaling theory on the samples irradiated with different dose of γ irradiation the critical exponents are determined and found to be < 2. The dark dc conductivity continuously decreases to 0 as temperature tends to zero. The steric value is low in the insulator side of conductivity, but high and almost saturated in the metallic side of conductivity. [ABSTRACT FROM AUTHOR]

A mathematical model of the diffusion interaction of a binary system with several phases on the equilibrium phase diagram is presented. The theoretical and calculated dependences of the layer thickness of each phase in the multiphase diffusion zone on the isothermal annealing time and the ratio of the diffusion parameters in the neighboring phases with an unlimited supply of both components were constructed. The phase formation and growth in the diffusion zone during 'reactive' diffusion corresponds to the equilibrium state diagram for two components, and the order of their appearance in the diffusion zone depends only on the ratio of the diffusion parameters in the phases themselves and on the duration of the incubation periods. The dependence of phase appearance on the incubation periods, annealing time, and difference in the movement rates of the components across the interface boundaries was obtained. An example of the application of the model for processing the experimental data on phase growth in a two-component three-phase system was given. [ABSTRACT FROM AUTHOR]

In order to study the effect of Zr on the microstructure and isothermal annealing performance of Cu-Cr in situ composites, Cu-15Cr and Cu-15Cr-0.24Zr alloys were prepared by means of vacuum medium frequency induction melting technology. The two kinds of test alloys with deformation of 3.79 were subjected to isothermal annealing test. The effects of Zr on the as-cast microstructure, the isothermal annealing structure and the tensile fracture morphology of Cu-15Cr alloy were studied by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). The results show that the addition of Zr leads to the formation of homogeneous and fine CuZr intermetallic compounds, which suppresses the formation electron microscopy of eutectic Cr phase and makes the eutectic Cr content much lower than that of Cu-15Cr alloy. The recrystallization temperature of the Cu matrix is increased, and it is maintained at a fine equiaxed crystal at 400 °C. After isothermal annealing at 400 °C for 220 h, the tensile strength, electrical conductivity and elongation of the test alloy containing Zr were 720 MPa, 68% IACS and 6.7%, respectively; while the tensile strength, electrical conductivity and elongation of the test alloys without Zr were 488 MPa, 70% IACS and 12.4%, respectively. [ABSTRACT FROM AUTHOR]

Understanding the time-dependence of thermal evolution and recovery of displacement damage is of great significance for evaluations of material performance in harsh fusion environments. In this study, the long-time thermal evolution of irradiation-induced defects has been investigated in heavy-ion irradiated tungsten at doses above the saturation limit. Polycrystalline tungsten samples were irradiated with 6 MeV copper ions up to 0.6 dpa at room temperature, followed by a series of isothermal annealing experiments at 653 and 1123 K for 5000, 10000 and 20000 s, respectively. Annealing at both temperatures triggered the coevolution of interstitial and vacancy defects, causing changes in defect morphology, size and population statistics. The damage microstructure remained stable after 5000 s at 653 K. Subtle variations in defect density and size were found, indicating the quasi-thermal-equilibrium state of the damage microstructure. In this temperature regime, small defect clusters were depleted via annihilation and absorption, while large defect clusters and defect-impurity complexes were pinned by traps requiring further thermal activation. Pronounced time-dependence in defect evolution was found at 1123 K. Defect recovery and defect coarsening became more prominent with increasing duration. Almost all dislocation networks dissociated into individual dislocation lines after 20000 s, while nano-sized voids and loops became fewer but gained an increase in size. These findings can be attributed to the collective impact of the increasing mobility of small vacancy clusters, the continual dissociation of large vacancy clusters and small voids, and the thermally activated detrapping of defect clusters from impurities and/or other traps. [ABSTRACT FROM AUTHOR]

We experimentally investigated the temperature dependence of the electrical conductivity and the kinetics of lead-silicate glass C87-2. The influence of mass transfer under the influence of an electric field on the electrical conductivity was also. evaluated via the dependence of the size of nanocrystals on the time of isothermal annealing.