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Showing 11 results for Annealing

Ebrahimi A.r., Yadegari M., Khosroshahi R.a.,
Volume 3, Issue 3 (12-2006)

In this study, commercially pure titanium/304L stainless steel explosion bonded clads have been annealed under argon atmosphere over the temperature range of 700-900°C for 1h.Microstructure of the clads have been investigated before and after anealing. X-ray diffraction studies revealed that the annealing products in the form of intermetallic phases were gradually formed at the interface of the annealed clads. It was also found that, the bonding zone width increased with temperature according to an Arrhenius type equation. On the base of this equation, the activation energy of bonding zone growth was found equal to about 66.5 kJ/mol. The bond strength of the diffusion annealed clads were evaluated stress relieved. The maximum average tensile strength of ~350MPa was obtained for the as-welded clad. It was found that the bond strength decreased with annealing at 700°C due to an increase in the width of brittle intermetallic layer.
H. Shahmir, M. Nili Ahmadabadi, F. Naghdi,
Volume 5, Issue 4 (12-2008)

Abstract: In the present study the effect of thermomechanical treatment (cold work and annealing) on the transformation behavior of NiTi shape memory alloys was studied. Differential scanning calorimetry was used to determine transformation temperature and its relation to precipitates and defects. Three alloys including Ti-50.3at.% Ni, Ti-50.5at.% Ni (reclamated orthodontic wires) and 50.6at.% Ni alloy were annealed at 673 K and 773 K for 30 and 60 min after 15% cold rolling. It was found that the transformation characteristics of these alloys are sensitive to annealing treatment and composition. The temperature range of transformation is broadened during cold working and after subsequent annealing, the intermediate phase was appeared. The peaks become sharper and close together on each cooling and heating cycle with increasing annealing temperature and time
M. Mohammadnejad, M. Ehteshamzadeh, S. Soroushian,
Volume 11, Issue 2 (6-2014)

Microstructure and corrosion performance of admiralty brass (ADB) and aluminum brass (ALB) alloys after passing different annealing heat treatments were investigated using optical and scanning electron microscope, energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), DC polarization measurements and electrochemical impedance spectroscopy (EIS). The results showed that heat treating of ALB caused gradient in aluminum concentration across the grains whose increased with increasing of annealing temperature. On the other hand, corrosion current density (i corr) of ADB in 3.5%NaCl media decreased with increasing of recrystallization, while ALB showed corrosion behavior inconsistent with ADB. The impedance measurements showed that corrosion rate of ADB decreased with increasing of exposure time from 0 to 15 days which could be related to the formation of SnO 2 surface film and the Sn-rich phases. While polarization resistance of ALB decreased by passing days in the corrosive media which could be associated to establishing of differential aluminum concentration cells.

M. S. Kaiser,
Volume 11, Issue 4 (12-2014)

The evaluation of texture as a function of recrystallization has been characterized for directly cold rolled Al-6Mg, Al-6Mg-0.4Sc and Al-6Mg-0.4Sc-0.2Zr alloys. Samples were annealed isothermally at 400 °C for 1 to 240 minutes to allow recrystallization. Recrystallization kinetics of the alloys is analyzed from the micro-hardness variation. Isothermally annealed samples of aluminum alloys were also studied using JMAK type analysis to see if there exists any correlation between the methods. Recrystallization fraction behavior between two methods the scandium added alloys show the higher variation due to precipitation hardening and higher recrystallization behavior. The scandium and zirconium as a combined shows the more variation due to formation of Al3(Sc, Zr) precipitate. From the microstructure it is also observed that the base Al-Mg alloy attained almost fully re-crystallized state after annealing at 400 °C for 60 minutes
H. Mirzakouchakshirazi, A. Eivani, Sh. Kheirandish,
Volume 14, Issue 4 (12-2017)

Effects of annealing treatment after equal channel angular pressing (ECAP) on the interface properties and shear bond strength of Al/Cu bimetallic rods were investigated. For the as-deformed samples, the one with two passes of ECAP indicated higher shear bond strength. Formation of a layer of intermetallic compounds after annealing treatment is confirmed. In general, by increasing annealing temperature, thickness of intermetallic compounds at the interface increases. Shear bond strength was initially reduced by annealing at 200, 250 and 300 ͦ C and increased at 350 ͦ C. With further increase in annealing temperature to 400 ͦ C, shear bond strength slightly decreased which is correlated to the increased thickness of the intermetallic compounds.

E. Abbasi, K. Dehghani, T. Niendorf, S. V. Sajadifar,
Volume 17, Issue 4 (12-2020)

The effect of cooling rate after annealing at 900 °C on the microstructure and hardness of high entropy alloys was investigated using two typical samples with the chemical composition of Co16Cr14.5Fe29Mn11.5Ni29 and Co11.5Cr7Fe27Mn27Ni27(Nb0.08C0.5) (at%). The microstructural characterisation and hardness measurements were carried out by optical microscopy, scanning electron microscopy, wavelength-dispersive X-ray spectroscopy, electron back scattered diffraction, X-ray diffraction technique and Vickers hardness testing. A face centred cubic crystal structure matrix was observed in both alloys before and after annealing and regardless of cooling conditions. SEM analyses revealed an extensive precipitation in Co11.5Cr7Fe27Mn27Ni27(Nb0.08C0.5) alloy after annealing. It was also found that air/furnace cooling can enhance grain growth-coarsening just in Co16Cr14.5Fe29Mn11.5Ni29. However, the hardness results generally showed insignificant hardness variations in both alloys after water-quenching, air-cooling and furnace-cooling. The results suggested that the hardness is mainly controlled by solid solution strengthening.
Sasan Ranjbar Motlagh, Hosein Momeni, Naser Ehsani,
Volume 18, Issue 1 (3-2021)

In this study, the effect of annealing treatment on microstructure and mechanical properties of Nb-10Hf-1Ti wt.% produced by Spark Plasma Sintering (SPS) was investigated. Scanning electron microscope (SEM), optical microscopy, X-ray diffraction analysis, hardness, and uniaxial tension test were used. Annealing treatment was carried out in a vacuum of 10-3 Pa at 1150 °C for 1, 3, 5, and 7 hours and in an argon atmosphere at 1350 °C for 5 hours. Internal oxidation and subsequent hafnium oxide formation causes the hardening of the C103 alloy and drastically increases hardness and tensile strength. Although HfO2 particles formed in the grain boundary cause brittleness and cleavage fracture of samples. Volume fraction, particle size, and mean interparticle spacing of oxides significantly change by annealing and subsequently the mechanical properties are affected. The SPSed sample at 1500 ℃ is softened by annealing at 1150 ℃ for 5 hours and its hardness and yield strength are reduced from 303 Hv to 230 Hv and 538 MPa to 490 MPa respectively. While annealing at 1350 ℃for 5 hours increases hardness and yield strength increases to 343 Hv and 581 MPa. 
Namrata Saxena, Varshali Sharma, Ritu Sharma, Kamlesh Kumar Sharma, Kapil Kumar Jain,
Volume 18, Issue 2 (6-2021)

The work reported in this paper was focused on the investigation of surface morphological, microstructural, and optical features of polycrystalline BaTiO3 thin film deposited on p-type Si < 100 > substrate using e-beam PVD (physical vapor deposition) technique. The influence of annealing over the surface morphology of the thin film was analyzed by X-ray diffraction, atomic force microscopy and scanning electron microscopy characterization methods. When the annealing temperature was increased from as-deposited to 800 °C there was a significant growth in the grain size from 28.407 nm to 37.89 nm. This granular growth of BaTiO3 made the thin film appropriate for nanoelectronic device applications. The roughness of the annealed film got increased from 31.5 nm to 52.8 nm with the annealing temperature. The optical bandgap was computed using Kubelka-Munk (KM) method which got reduced from 3.93 eV to 3.87 eV for the as-deposited to the 800 °C annealed film. The above reported properties made the annealed film suitable for optoelectronic applications. For polycrystalline BaTiO3 thin film the refractive index varied from 2.2 to 1.98 from 400 to 500 nm and it was 2.05 at 550 nm wavelength. The broad peaks in Raman spectra indicated the polycrystalline nature of the thin film. It had been also observed that with the annealing temperature the intensity of the Raman bands got increased. From these results, it was proved that annealing significantly improved the crystallinity, microstructural, surface morphological and optical features of the barium titanate thin film which made it suitable as sensors in biomedical applications as it is cost-effective, lead-free and environment friendly material.
Masumeh Mohammadi, Hamidreza Rezaei Ashtiani,
Volume 18, Issue 2 (6-2021)

The hot deformation behavior of the heat-treated AA6061 and AA 6063 aluminum alloys by T6-1, T6-2 artificial aging treatment, and O annealing treatment were studied by compression testing over a temperature range of 350–550  and strain rates of 0.005-0.1 s-1. It was observed that the flow stresses of the studied aluminum alloys treated by the T6-1 and T6-2 heat treatments were significantly higher than those of the O annealing treatment. Moreover, the stress-strain curves of the heat-treated alloys by the T6-1, T6-2, and O heat treatments demonstrated significant softening during deformation at the lowest strain rate under any of the deformation conditions. For several strains, the activation energy of hot deformation was specified and obtained to vary significantly with strain for the heat-treated alloys by the T6-1 and T6-2 treatments. The stress-strain data calculated from a linear equation, with strain-dependent parameters, shows a great fit with the experimental data for the heat-treated aluminum alloys.
Rabah Bobaaya, Omar Allaoui, Mokhtar Djendel, Samir Benaniba,
Volume 18, Issue 3 (9-2021)

Coatings based on chromium borides and chromium carbides are commonly employed in applications requiring mechanical performance, such as high hardness and low friction coefficient, as well as corrosion resistance. In this work, we made layers of chromium borides and chromium carbides on the surface of low carbon steel through some specific treatments. For chromium borides, the boriding treatment in a solid medium at 900 °C for 4 hours followed by chromium electroplating on the steel surface and finally the application of annealing treatment at temperatures at 950 °C for 1 and 2 hours. For chromium carbides, the cementation in a solid medium followed by electroplating of chromium on the surface and finally the application of annealing treatment at temperatures between 500 and 1100 °C for 1 hour. The obtained results show that, in the first case, boron diffusion and chromium deposition lead to chromium borides on the treated surface. Similarly, for the second case, the cemented layer and the chromium deposited on the surface combine to form chromium carbides on the treated surface after annealing. The characteristics of the chromium borides and chromium carbides obtained are very similar to those of chromium borides and chromium carbides obtained by other processes.

Yemurai Vengesa, Arash Fattah-Alhosseini, Hassan Elmkhah, Omid Imantalab,
Volume 18, Issue 4 (12-2021)

The main purpose of this investigation is to assess the effect of post-deposition annealing treatment on the electrochemical behavior of TiN coating developed on AISI 304 stainless steel substrate using cathodic arc evaporation physical vapor deposition (CAE-PVD). Post-annealing treatment at 400 ºC was performed on the coated substrate for 1 h. The studied samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) tests. The preferred orientation of TiN (111) was identified by XRD patterns and the crystallinity of the coating increased after annealing treatment. SEM observations indicated that TiN coatings free of cracks were successfully developed on the substrate. The electrochemical measurements elucidated that the annealed coating had better corrosion resistance compared to that of the as-deposited coating with a lower current corrosion density. This investigation implied that improved corrosion performance of the TiN coating can achieved by performing post-deposition annealing treatment.

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