This study aims to find out the crucial variations in the mechanical
performance and characterization of Bi-2223 superconducting compounds with the
diffusion annealing temperatures interval 650 °C-850 °C by means of Vickers hardness measurements
exerted at the different applied indentation test loads (0.245 N-2.940 N) and derived theoretical findings. All
the experimental measurement results and theoretical evidences declare that the
mechanical characterization and performance are obtained to improve with the
increment in the diffusion annealing temperature up the value of 700 °C as a
consequence of decrement in the grain boundary coupling problems, local
structural distortions, grain misorientations, lattice strains, lattice
defects, disorders and dislocations in the adjacent layers. Namely, the optimum annealing
temperature of 700 °C resulting in the optimum penetration
of Ni impurities into both the superconducting grains and over the grain
boundaries develops the crystallinity of Bi-2223
crystal structure. In other words, the surface energy related to the
crack-initiating omnipresent flaws, void/crack propagation and dislocation
movement reduces due to the augmented critical stress value. In this respect,
the diffusion annealing temperature of 700 °C develops the mechanical durability, stiffness, ideal fracture and flexural strength. However,
after the certain diffusion annealing temperature value of 700 °C, the crystallinity tends to degrade considerably and in
fact dwelling in the worst crystal structure for 850 °C annealing
temperature. Accordingly, the initial
crack growths, sizes of crack-producing flaws, void/crack propagation and
dislocation movement in the copper-oxide consecutively stacked layers reach much more rapidly to the critical speeds due to the
increased stress amplification so that the Bi-2223 compound with the augmented
brittle behavior breaks at even lower test load.
Moreover, it is observed that the presence of optimum nickel impurities
in the crystal structure strengthens the standard indentation size effect behavior.
Bi-2223 crystal structure Ni impurity diffusion annealing temperature cracks/voids dislocations
Birincil Dil | İngilizce |
---|---|
Konular | Makine Mühendisliği |
Bölüm | Araştırma Makalesi |
Yazarlar | |
Yayımlanma Tarihi | 1 Ekim 2018 |
Gönderilme Tarihi | 4 Ekim 2017 |
Kabul Tarihi | 22 Kasım 2017 |
Yayımlandığı Sayı | Yıl 2018 |
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.