Showing 4 results for Bayat
M. Sadeghi, M. Hadi, O. Bayat, H. Karimi,
Volume 17, Issue 1 (March 2020)
Abstract
In this paper a constitutive equation was considered for the isothermal hot compression test of the Mn-Ni-Cr alloy. The hot compression test was performed in the strain rate range of 0.001-0.1 s-1 and deformation temperature was varied from 700 to 900 °C. A considerable reduction in flow stress was observed regardless of the strain rate when temperature was increased from 700 to 750 °C. DTA and XRD evaluation revealed that the removal of Mn3Cr phase and formation of the single solid solution phase were the reason for the flow stress reduction. At the low deformation temperature (700°C) and the high strain rate (0.1 s-1), a partially recrystallized microstructure was observed; this was such that with increasing the temperature and decreasing the strain rate, a recrystallized microstructure was completed. Also, the relationships between flow stress, strain rate and deformation temperature were addressed by the Zener-Holloman parameter in the exponent type with the hot deformation activation energy of 301.07 KJ/mol. Finally, the constitutive equation was proposed for predicting the flow stress at various strain rates and temperatures.
Morteza Hadi, Omid Bayat, Hadi Karimi, Mohsen Sadeghi, Taghi Isfahani,
Volume 19, Issue 1 (March 2022)
Abstract
In this research, the effect of initial microstructure and solution treatment on rollability and crystallographic texture of a Cu-Mn-Ni-Sn alloy has been investigated. The initial tests indicated that the rolling of the alloy at different temperature conditions is not possible due to formation of second phases. Herein to eliminate the segregated phases, according to DTA analysis, proper temperature for solution treatment was selected as 750°C applied at different periods of time. The obtained results showed that after 15-hour solution treatment, the complete elimination of Sn, Mn, Ni, and Fe-rich phases can be achieved. Also, the peaks of XRD shifted to the higher angles indicating that the alloying elements are dissolved. Meanwhile, the intensity of the texture reduced and the dominant texture changed from Goss and Brass-texture to Copper-texture. Accordingly, the amount of maximum total reduction at the rolling process increased from 16.37 to 109.46 after solution treatment.
Behzad Pourghasemi, Vahid Abouei, Omid Bayat, Banafsheh Karbakhsh Ravari,
Volume 19, Issue 3 (September 2022)
Abstract
It has long been thought-provoking and challenging as well for researchers to design and produce a special low-modulus β titanium alloy such as Ti‐35Nb‐7Zr‐5Ta, representing optimal mechanical properties that is needed to successfully simulate bone tissue. In order to identify the key effects of processing pathways on the development of microstructure, Young’s modulus, and strength, a nominal Ti-35Nb-7Zr-5Ta alloy was made via casting, hot forging, homogenizing, cold rolling and finally annealing. Results from tensile test alongside microscopic and XRD analysis confirm the importance influence of processing method on fully β phase microstructure, low elastic modulus and high strength of the alloy. The specimen with post-deformation annealing at 500 °C demonstrated the Young’s modulus of 49.8 GPa, yield strength of 780 MPa and ultimate tensile strength of 890 MPa, all of which are incredibly close to that of bone, hence suitable for orthopedic implants. At temperature above 500 °C, a sharp fall was observed in the mechanical properties.
Hussein Ali Jan Miran, Zainab Naji Abdullah, Mohammednoor Altarawneh, M Mahbubur Rahman, Auday Tariq Al-Bayati, Ebtisam M-T. Salman,
Volume 20, Issue 1 (March 2023)
Abstract
This contribution evaluates the influence of Cr doping on the ground state properties of SrTiO3 Perovskite using GGA-PBE approximation. Results of the simulated model infer agreement with the previously published literature. The modification of electronic structure and optical properties due to Cr3+ doping levels in SrTiO3 has been investigated. Structural parameters infer that Cr3+ doping alters the electronic structures of SrTiO3 by shifting the conduction band through lower energies for the Sr and Ti sites. Substituting Ti site by Cr3+ results the energy gap in being eliminated revealing a new electrical case of conducting material for the system. Furthermore, it has been noticed that Cr doping either at Sr or Ti positions could effectively develop the SrTiO3 dielectric constant properties. Consequently, Cr3+ is an effective dopant due to enhancing the optical absorption properties, thus opening up new prospects for optoelectronic applications.
