Hardness and microstructural analysis of Bi1.6Pb0.4Sr2Ca2−xSmxCu3Oy polycrystalline superconductors

Kölemen, Uğur; Uzun, Orhan; Yilmazlar, Mustafa; Güçlü, N.; Yanmaz, E.

doi:10.1016/j.jallcom.2005.09.023

Cited by 58 publications

(22 citation statements)

References 28 publications

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“…The calculated values of W are found to be larger than the acceptable values [75]. Similar results were observed by Kölemen et al [32] [76], Vickers nanoindentation tests were conducted on the similar BSCCO materials and plastic indentation impressions were observed at the load as low as 10 mN. The constant A 1 is suggested to be a measure of the load independent microhardness H HKin , and their values increase as x increases to 0.025 and then decrease for x > 0.025, confirming the experimental variation of H V with x.…”

Section: 2 Hays-kendall Approachsupporting

confidence: 88%

“…The presence of elastic deformation along with plastic deformation is the reason of ISE behavior for our samples. Also, it is found that 0 d changes randomly, and similar behavior was reported by previous studies on BSCCO system [32,33,78]. The constant 2 A is related to load independent hardness EPDin H , and their values increase as x increases to 0.025 and then decrease for x > 0.025, confirming the experimental variation of H V with x.…”

Section: 3 Elastic/plastic Deformation Modelsupporting

confidence: 87%

“…Therefore, one can conclude that HK approach is not suitable for describing our experimental data. Similar behavior of failure of HK model in BSCCO system was observed in many previous works [14,32,33,75,76,78]. While, for EPD model, it is found that 0 d changes randomly, and the values of the true hardness …”

Section: 4 Proportional Sample Resistance Modelsupporting

confidence: 84%

“…The H V -F curve behavior shows that the H V decreases non-linearly as the applied load increases up to 3 N, beyond which the curves tend to attain saturation (nearly plateau) region. This non-linear behavior is also observed for (Bi,Pb)-2223 phase [12][13][14][15][30][31][32][33][34] and it is known as indentation size effect (ISE). The ISE behavior can be explained qualitatively on the basis of penetration depth of the indenter.…”

Section: Characterization and Investigationmentioning

confidence: 89%

“…The effect of chemical substitution/addition on Vickers microhardness for (Bi,Pb)-2223 phase was studied by many groups [12][13][14][15][32][33][34]. It was found that the substitution of Sm at Ca site increases H V due to the enhancement in grain connectivity, and the modified proportional specimen resistance model was found to be the most successful model describing the load independent microhardness [32]. Addition of Gd 3+ ions to (Bi,Pb)-2223 degrades the mechanical properties [33,34].…”

Section: Introductionmentioning

confidence: 99%

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Electrical and mechanical properties of (Bi,Pb)-2223 substituted by holmium

et al. 2016

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Abstract:The effect of the partial substitution of Ca 2+ by Ho 3+ ions on the electrical and mechanical properties of the superconducting phase (Bi,Pb)-2223 was studied. Superconducting samples of the type (Bi 1.8 Pb 0.4 )Sr 2 Ca 2.1−x Ho x Cu 3.1 O 10+δ were prepared by solid-state reaction technique under ambient pressure, and characterized by means of X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The superconducting transition temperature T c and pseudogap temperature T * were estimated from electrical resistivity measurements, while the critical current density J c was determined from I-V curves. The electrical resistivity data were discussed according to bipolaron model in the absence of thermally excited individual polarons. The sample with x = 0.025 showed the highest phase volume fraction, T c , and J c . Room temperature Vickers microhardness measurements were carried out at different applied loads (0.25-5 N) in order to investigate the performance of the mechanical properties of (Bi 1.8 Pb 0.4 )Sr 2 Ca 2.1−x Ho x Cu 3.1 O 10+δ phase. It was found that all the samples exhibit normal indentation size effect (ISE). The Vickers microhardness number H V increased as x increased from 0 to 0.025. The experimental results were discussed in view of Meyer's law, Hays-Kendall (HK) approach, elastic/plastic deformation (EPD) model, and proportional specimen resistance (PSR) model. The load independent (true) microhardness of (Bi 1.8 Pb 0.4 )Sr 2 Ca 2.1−x Ho x Cu 3.1 O 10+δ superconducting samples showed identical behavior to that of the PSR model.

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Section: 2 Hays-kendall Approachsupporting

confidence: 88%