Effect of annealing temperature on microstructure and mechanical properties of Mg-Zn-Zr-Nd alloy with large final rolling deformation

In this study,the Mg-3Zn-0.5Zr-χNd(χ=0,0.6)alloys were subjected to final rolling treatment with large deformation of 50%.The impact of annealing temperatures on the microstructure and mechanical properties was investigated.The rolled Mg-3Zn-0.5Zr-0.6Nd alloy exhibited an ultimate tensile strength of 386 MPa,a yield strength of 361 MPa,and an elongation of 7.1%.Annealing at different temperatures resulted in reduced strength and obviously increased elongation for both alloys.Optimal mechanical properties for the Mg-3Zn-0.5Zr-0.6Nd alloy were achieved after annealing at 200℃,with an ultimate tensile strength of 287 MPa,a yield strength of 235 MPa,and an elongation of 26.1%.The numerous deformed microstructures,twins,and precipitated phases in the rolled alloy could impede the deformation at room temperature and increase the work hardening rate.After annealing,a decrease in the work hardening effect and an increase in the dynamic recovery effect were obtained due to the formation of fine equiaxed grains,and the increased volume fraction of precipitated phases,which significantly improved the elongation of the alloy.Additionally,the addition of Nd element could enhance the annealing recrystallization rate,reduce the Schmid factor difference between basal and prismatic slip systems,facilitate multi-system slip initiation and improve the alloy plasticity.

Impact of annealing temperature on the ferroelectric properties of W/Hf_(0.5)Zr_(0.5)O_(2)/W capacitor

Crystallization annealing is a crucial process for the formation of the ferroelectric phase in HfO_(2)-based ferroelectric thin films.Here,we systematically investigate the impact of the annealing process,with temperature varied from 350℃to 550℃,on the electricity,ferroelectricity and reliability of a Hf_(0.5)Zr_(0.5)O_(2)(HZO;7.5 nm)film capacitor.It was found that HZO film annealed at a low temperature of 400℃can effectively suppress the formation of the monoclinic phase and reduce the leakage current.HZO film annealed at 400℃also exhibits better ferroelectric properties than those annealed at 350℃and 550℃.Specifically,the 400℃-annealed HZO film shows an outstanding 2Pr value of 54.6μC·cm^(-2)at±3.0 MV·cm^(-1),which is relatively high compared with previously reported values for HZO film under the same electric field and annealing temperature.When the applied electric field increases to±5.0 MV·cm^(-1),the 2Pr value can reach a maximum of 69.6μC·cm^(-2).In addition,the HZO films annealed at 400℃and 550℃can endure up to bout 2.3×10^(8)cycles under a cycling field of 2.0 MV·cm^(-1)before the occurrence of breakdown.In the 400℃-annealed HZO film,72.1%of the initial polarization is maintained while only 44.9%is maintained in the 550℃-annealed HZO film.Our work demonstrates that HZO film with a low crystallization temperature(400℃)has quite a high ferroelectric polarization,which is of significant importance in applications in ferroelectric memory and negative capacitance transistors.

Effect of annealing temperature on joints of diffusion bonded Mg/Al alloys

To study the effect of annealing temperature on the joints between magnesium and aluminum alloys, and improve the properties of bonding layers, composite plates of magnesium alloy（AZ31 B） and aluminum alloy（6061） were welded using the vacuum diffusion bonding method. The composite specimens were continuously annealed in an electrical furnace under the protection of argon gas. The microstructures were then observed using scanning electron microscopy. X-ray diffractometry was used to investigate the residual stresses in the specimens. The elemental distribution was analyzed with an electron probe micro analyzer. The tensile strength and hardness were also measured. Results show that the diffusion layers become wide as the heat treatment temperature increases, and the residual stress of the specimen is at a minimum and tensile strength is the largest when being annealed at 250 ℃. Therefore, 250 ℃ is the most appropriate annealing temperature.

Effect of annealing temperature on martensitic transformation of Ti_(49.2)Ni_(50.8) alloy processed by equal channel angular pressing

The effect of annealing temperature on the martensitic transformation of a Ti49.2Ni50.8 alloy processed by equal channel angular pressing （ECAP） was investigated by X-ray diffraction （XRD）, transmission electron microscopy （TEM） and differential scanning calorimetry （DSC）. The as-ECAP processed and subsequently annealed Ti49.2Ni50.8 alloys consist of B2 parent phase, Ti4Ni2O phase and B19′ martensite at room temperature. Upon cooling, all samples show B2→R→B19′ two-stage transformation. Upon heating, when the annealing temperature is less than 400℃, the samples show B19′→R→B2 two-stage transformation; when the annealing temperature is higher than 500 ℃, the samples show B19′→B2 single-stage transformation. The B2-R transformation is characterized by wide interval due to the dislocations introduced during ECAP.

Effects of annealing temperature on the microstructure and properties of the 25Mn-3Si-3Al TWIP steel

Microstructures and mechanical properties of the 25Mn twinning induced plasticity （TWIP） steel at different annealing temperatures were investigated. The results indicated that when the annealing temperature was 1000℃, the 25Mn steel showed excellent comprehensive mechanical properties, the tensile strength was about 640 MPa, the yield strength was higher than 255 MPa, and the elongation was above 82%. The microstructure was analyzed by optical microscopy （OM）, X-ray diffraction （XRD）, and transmission electron microscopy （TEM）. Before deformation the microstructure was composed of austenitic matrix and annealing twins at room temperature; at the same time, a significant amount of annealing twins and stacking faults were observed by TEM. Mechanical twins played a dominant role in deformation and as a result the mechanical properties were found to be excellent.

Effect of decarburization annealing temperature and time on the carbon content, microstructure, and texture of grain-oriented pure iron

In this study,the effect of decarburization annealing temperature and time on the carbon content,microstructure,and texture of grain-oriented pure iron was investigated by optical microscopy and scanning electron microscopy with electron-backscatter diffraction. The results showed that the efficiency of decarburization dramatically increased with increasing decarburization temperature. However,when the annealing temperature was increased to 825°C and 850°C,the steel's carbon content remained essentially unchanged at 0.002%. With increasing decarburization time,the steel's carbon content generally decreased. When both the decarburization temperature and time were increased further,the average grain size dramatically increased and the number of fine grains decreased; meanwhile,some relatively larger grains developed. The main texture types of the decarburized sheets were approximately the same: {001}<110> and {112~115}<110>,with a γ-fiber texture. Furthermore,little change was observed in the texture. Compared with the experimental sheets,the texture of the cold-rolled sheet was very scattered. The best average magnetic induction(B_(800)) among the final products was 1.946 T.

Effect of annealing temperature on microstructure and electrochemical performance of La_(0.75)Mg_(0.25)Ni_(3.5)Co_(0.2) hydrogen storage electrode alloy

To improve the cyclic stability of La-Mg-Ni system alloy, as-cast La0.75Mg0.25Ni3.5Co0.2 alloy was annealed at 1123, 1223, and 1323 K for 10 h in 0.3 MPa argon. The microstructure and electrochemical performance of different annealed alloys were investigated systematically by X-Ray Diffraction （XRD）, Scanning Electron Microscopy （SEM）, X-Ray Photoelectron Spectroscopy （XPS）, and electrochemical experiments. The results obtained by XRD and SEM showed that the as-cast and annealed （1123 K） alloys had multiphase structure containing LaNis, （La, Mg）2（Ni, Co）7 and few LaNi2 phases. When annealing temperatures approached 1223 and 1323 K, LaNi2 phase disappeared. The annealed alloys at 1223 and 1323 K were composed of LaNi5, （La, Mg）2（Ni, Co）7 and （La, Mg）（Ni, Co）3 phases. With increasing annealing temperature, the maximum discharge capacity of the alloy decreased monotonously, but the cyclic stability was improved owing to structure homogeneity and grain growth after annealing, as well as the enhancement of anti-oxidation/corrosion ability and the suppression of pulverization during cycling in KOH electrolyte.

Effects of substrate temperature and annealing treatment on the microstructure and magnetic characteristics of TbDyFe films

A series of TbDyFe films were prepared by DC magnetron sputtering. The effects of substrate temperature and annealing temperature on the phase structure and the magnetic properties of the sample films were investigated. The an-nealing treatment has a significant influence on the microstructure and the magnetic properties of the sample. The results obtained by XRD indicate that the films deposited at a temperature lower than 525℃ are amorphous and have an easy magnetization direction perpendicular to the film plane. An RFe2 phase is formed in the sample annealed at 550℃ and the residual phases observed are Fe and rare earth oxide. The magnetic properties Hc and Mr/Ms of the film annealed at 550℃ obtain the maximum values,for which the formation of the RFe2 phase is mainly responsible. An annealing treatment leads to a rotation of the sample’s easy axis from being parallel to the film surface to becoming vertical.

Growth and annealing study of hydrogen-doped single diamond crystals under high pressure and high temperature

A series of diamond crystals doped with hydrogen is successfully synthesized using LiH as the hydrogen source in a catalyst-carbon system at a pressure of 6.0 GPa and temperature ranging from 1255 C to 1350 C.It is shown that the high temperature plays a key role in the incorporation of hydrogen atoms during diamond crystallization.Fourier transform infrared micro-spectroscopy reveals that most of the hydrogen atoms in the synthesized diamond are incorporated into the crystal structure as sp 3-CH 2-symmetric（2850 cm-1） and sp 3 CH 2-antisymmetric vibrations（2920 cm-1）.The intensities of these peaks increase gradually with an increase in the content of the hydrogen source in the catalyst.The incorporation of hydrogen impurity leads to a significant shift towards higher frequencies of the Raman peak from 1332.06 cm-1 to 1333.05 cm-1 and gives rise to some compressive stress in the diamond crystal lattice.Furthermore,hydrogen to carbon bonds are evident in the annealed diamond,indicating that the bonds that remain throughout the annealing process and the vibration frequencies centred at 2850 and 2920 cm-1 have no observable shift.Therefore,we suggest that the sp 3 C-H bond is rather stable in diamond crystals.

Effect of annealing temperature on the microstructure and optoelectrical properties of ZnO thin films and their application in self-powered accelerometers

This paper reports a piezoelectric nanogenerator(NG) with a thickness of approximately 80 μm for miniaturized self-powered acceleration sensors. To deposit the piezoelectric zinc oxide(ZnO) thin film, a magnetron sputtering machine was used. Polymethyl methacrylate(PMMA) and aluminum-doped zinc oxide(AZO) were used as the insulating layer and the top electrode of the NG, respectively. The experimental results show that the ZnO thin films annealed at 150℃ exhibited the highest crystallinity among the prepared films and an optical band gap of 3.24 eV. The NG fabricated with an AZO/PMMA/ZnO/stainless steel configuration exhibited a higher output voltage than the device with an AZO/ZnO/PMMA/stainless steel configuration. In addition, the annealing temperature affected the open-circuit voltage of the NGs;the output voltage reached 3.81 V when the annealing temperature was 150℃. The open-circuit voltage of the prepared self-powered accelerometer increased linearly with acceleration. In addition, the small NG-based accelerometer, which exhibited excellent fatigue resistance, can be used for acceleration measurements of small and lightweight devices.

Microstructural characteristics of AZ31 alloys rolled at room and cryogenic temperatures and their variation during annealing

This study investigates the microstructural characteristics of AZ31 Mg alloys rolled at room temperature(RT)and cryogenic temperature(CT)and the variation in their microstructure and hardness during subsequent annealing.Cryorolling induces the formation of more side cracks than does RT rolling,because of the reduction in the ability of the material to accommodate deformation at CT.Numerous{10-11}contraction and{10-11}-{10-12}double twins are formed in both the material rolled at RT and that rolled at CT,because the grains of the initial material are favorably oriented for{10-11}twinning under rolling.The RT-rolled material has a higher dislocation density than the cryorolled material,and more twins are uniformly distributed throughout the former material.As a result,static recrystallization during subsequent annealing is more pronounced in the RT-rolled material,which results in the formation of a highly recrystallized homogeneous microstructure after annealing.In contrast,the formed twins are predominantly present along the shear bands in the cryorolled material,as a result of which this material has an inhomogeneous bi modal structure containing a large amount of coarse unrecrystallized grains after annealing.The hardness of the annealed RT-rolled material is higher than that of the annealed cryorolled material owing to the finer grain structure of the former.

Effect of Zr additions and annealing temperature on electrical conductivity and hardness of hot rolled Al sheets

The influence of annealing cycles up to 650 °C on the specific conductivity and hardness（HV） of hot-rolled sheets of Al alloys containing up to 0.5% Zr（mass fraction） was studied.Using analytical calculations of phase composition and experimental methods（scanning electron microscopy,transmission electron microscopy,electron microprobe analysis,etc）,it is demonstrated that the conductivity depends on the content of Zr in the Al solid solution which is the minimum after holding at 450 °C for 3 h.On the other hand,the hardness of the alloy is mainly caused by the amount of nanoparticles of the L12（Al3Zr） phase that defines the retention of strain hardening.It is shown that the best combination of electrical conductivity and hardness values can be reached within an acceptable holding time at the temperature about 450 °C.

Effects of Annealing Process on Crystallization and Low Temperature Resistance Properties of PP-R Composites

The effects of the annealing process on the mechanical properties and crystallization behaviors of polypropylene random copolymer（PP-R） composites were investigated using differential scanning calorimetry（DSC）, wide-angle X-ray diffraction（WAXD）, and dynamic mechanical analysis（DMA）, and scanning electron microscopy（SEM）. The experimental results indicated that the annealing process significantly influenced the comprehensive properties of PP-R composites. At temperatures below 23 ℃, the impact strength of the PP-R composites annealed at 120 ℃ for 6 h was relatively high at 74.73 k J/m^2, which was 16.8% higher than that of the samples annealed at 80 ℃ for 6 h. At low temperatures（-30-0 ℃）, the impact strength ranged from approximately 13.31 k J/m^2 to 54.4 k J/m^2. In addition, the annealing process conducted at 120 ℃ for 6 h improved the crystalline structure and low-temperature toughness of the PP-R composites and induced α-form to β-form crystal transformation. The work provides a possible method to reinforce and toughen the semicrystalline polymer at low temperatures（-30-0 ℃） by annealing.

EFFECT OF ANNEALING TEMPERATURE ON TEXTURE OF COLD－ROLLED Ni47Ti44Nb9 SHEET

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Annealing Temperature Effects of TiO2 Nanofiber Anodes for the Rechargeable Lithium Ion Batteries

TiO2 nanofibers（TiO2/NFs） have been synthesized through an electrospinning method and annealed at 400, 500 and 600 ℃ to optimize their systems. The effects of annealing temperature on the electrochemical properties for lithium ion batteries（LIBs） are assessed. The obtained LIB properties for TiO2 nanofiber anodes annealed at 400 ℃（denoted as TiO2/NFs-400） are much better than those of TiO2/NFs-500 and TiO2/NFs-600. The TiO2/NFs-400 anodes show good LIB performance with capacities of 180 and 150 m Ah/g tested at 200 and 600 m A/g after 100 cycles with almost no capacity loss and superb rate performance. The XRD results show that the pure anatase phase TiO2 can form at 400 ℃ for TiO2/NFs-400, while mixed phases of anatase and rutile are emerged at TiO2/NFs-500 and TiO2/NFs-600. Furthermore, the TiO2 nanoparticles are combined in nanofibers, and their corresponding crystal particle size for TiO2/NFs-400 was smaller than that of the other two samples. It is concluded that the superior electrochemical performance of the TiO2/NFs-400 anodes could be due to their pure crystal of anatase, small nanoparticles and non-ideal crystal lattices.

Effects of annealing temperature on microstructure and ferroelectric properties of Bi_(0.5)(Na_(0.85)K_(0.15))_(0.5)TiO_3 thin films

Bi0.5(Na0.85K0.15)0.5TiO3(BNKT15) thin films were synthesized by metal-organic decomposition(MOD) at annealing temperatures of 650,680,710 and 740℃,and the effects of annealing temperature on the microstructure,dielectric properties,remnant polarization(2Pr) and leakage current density were studied with X-ray diffractometer,atomic force microscope,precision impedance analyzer,ferroelectric analysis station and semiconductor parameter tester.The results show that the thin film annealed at 710℃ exhibits a typical perovskite structure without predominant orientation and a smooth surface with evenly distributed grains.2Pr value(67.4 μC/cm2 under 830 kV/cm) and the leakage current density(1.6×10-6 A/cm2 at 170 kV/cm) for BNKT15 thin film annealed at 710℃ are better than those for thin films annealed at other temperatures.

The effect of high-temperature annealing on LaFe_(11.5)Si_(1.5) and the magneto-caloric properties of La_(1-x)Ce_xFe_(11.5)Si_(1.5) compounds

The powder X-ray diffraction patterns of LaFell.sSil.5 compounds annealed at different high temperatures from 1323 K （5 h） to 1623 K （2 h） show that a large amount of 1：13 phase begins to form in LaFell.sSiL5 compound annealed at 1423 K （5 h）. In the temperature range from 1423 to 1523 K, ^-Fe and LaFeSi phases rapidly decrease to form 1：13 phase. LaFeSi phase is rarely observed, and the most amount of 1：13 phase is obtained in the compound annealed at 1523 K （5 h）. With the annealing temperature increasing to 1573 and 1623 K, LaFeSi is detected again in the LaFell.sSil.s compound. According to the results of annealing at different high-temperatures, the Lal-xCexFelt.sSit.5 compounds are annealed at high temperatures of 1373 K （2 h） ＋ 1523 K （5 h）. The main phase is NaZn13-type phase, and the impurity is a small amount of et-Fe in Lal-xCexFexx.sSil.5 compounds with 0 〈 x 〈 0.35, and there is a large amount of CeaFe17 phase in Lao.sCeo.sFela.sSil.s. It indicates that the substitution of cerium atoms for La in LaFelLsSil.5 compounds has limit. At the same time, the substitution of Ce for La has large effect on magnetocaloric properties. With increasing Ce content from x = 0 to x = 0.35, the Curie temperature decreases linearly from 196 to 168 K, the magnetic entropy change increases from 16.5 to 57.3 J-kg-kK-1 in a low magnetic field change of 0-2 T, and the thermal hysteresis also increases from 3 K to 8 K.

Annealing Temperature dependence of Photoluminescence from Silicon-rich silica Films

The silicon-rich silica films were prepared by a dual-ion-beam co-sputtering method from a composite Target in an argon atmosphere. The structure of the films studied by the aid of TEM and XRD is amorphous. The photoluminescence (PL) spectra were found to have a 4- luminescent band peak at 320 nm, 410 nm, 560 nm, and 630 nm, respectively, at room temperature. The intensity and the wavelength position of PL are dependent on annealing temperature (Ta), and the luminescent mechanism is analyzed.

Effect of Annealing Temperature on the Formation of Silicides and the Surface Morphologies of PtSi Films

The effect of annealing temperature on the formation of the PtSi phase. distribution of silicides and the surface morphologies of silicides films is investigated by XPS. AFM. It is shown that the phase sequences of the films change from Pt-Pt2Si-PtSi-Si to Pt+Pt2Si+PtSi-PtSi-Si or Pt+Pt2Si+PtSi-PtSi-st with an increase of annealing temperature and the reason for the formation of mixed layers is discussed.

Effect of the annealing temperature on the long-term thermal stability of Pt/Si/Ta/Ti/4H–SiC contacts

The Pt/Si/Ta/Ti multilayer metal contacts on 4H-Si C are annealed in Ar atmosphere at 600°C-1100°C by a rapid thermal processor（RTP）. The long-term thermal stability is evaluated by aging the annealed contact at 600°C in air. The contact＇s properties are determined by current-voltage measurement, and the specific contact resistance is calculated based on the transmission line model（TLM）. Transmission electron microscope（TEM） and energy-dispersive x-ray spectrometry（EDX） are used to characterize the interface morphology, thickness, and composition. The results reveal that a higher annealing temperature is favorable for the formation of an Ohmic contact with a lower specific contact resistance, and causes the rapid degradation of the Ohmic contact in the aging process.