Analysis of indentation size effect (ISE) behavior in low-load Vickers microhardness testing of (Sm123)(1-x)(Nd123)(x) superconductor system

Indentation size effect (ISE) for (Sm123)(1-x) (Nd123)(x) superconducting samples which were fabricated by the solid state reaction technique for values of x = 0.00, 0.05, 0.10, 0.20, and 0.30 was investigated by analyzing the theoretical models. When the experimental data of a number of single crystals which have the different crystal structure and different chemical bonding inside the poly-crystallined samples were analyzed with the ISE models, the sample encountering with resistance and elastic deformation was observed as well as plastic deformation. The microhardness values on different surfaces of materials were calculated by using Meyer Law, proportional specimen resistance model, modified proportional specimen resistance model, elastic/plastic deformation model and the Hays-Kendall (HK) approach. The results showed that the HK approach was determined as the most successful model. Furthermore, X-ray powder diffraction and scanning electron microscope measurements were analyzed for superconducting properties of (Sm123)(1-x)(Nd123)(x) superconductor system. The results showed that microhardness values at the minimum load and averaged plateau region of load increased with increase of Nd123 concentration. Nd123 content can be used as to be estimated the microhardness value of (Sm123)(1-x)(Nd123)(x) superconducting sample in the range of 0.878-2.717 GPa. The control of the microhardness value by using Nd123 content in (Sm123)(1-x)(Nd123)(x) superconducting structure can be useful in technological applications in superconductivity industry

Improvement of the Nature of Indentation Size Effect of Bi-2212 Superconducting Matrix by Doped Nd Inclusion and Theoretical Modeling of New Matrix

Turkoz, Mustafa Burak/0000-0002-4127-7650; Kaya, Seydanur/0000-0002-6894-9082WOS: 000336403800009Neodmium (Nd) inclusions at different stoichiometric ratios (x=0.0, 0.001 %, 0.005 %, 0.01 %, 0.05 %, 0.1 %) are doped in the Bi-2212 superconducting samples and the samples obtained are subjected to the sintering process at 840 C-a similar to constant temperature for 72 hours. The effect of Nd doping on the structural and mechanical properties of prepared samples is investigated by the standard characterization measurements. XRD and SEM measurements are performed to obtain information about surface morphology, phase ratios, lattice parameters and particle size. Moreover, Vickers microhardness (H (V) ) measurements are exerted to investigate the mechanical properties of the all samples in detail. It is found that all the properties given above retrogress with the increase of the Nd concentration in the Bi-2212 superconducting core. However, the ISE nature of the materials improves systematically. Additionally, the experimental results of microhardness measurements are analyzed using Meyer's law, PSR, MPSR, EPD models and HK approach. The results show that Hays-Kendall approach is determined as the most successful model

Effect of Zn content on microstructure and mechanical performance in Bi1.8Sr2Ca2Cu3.2-xZnxO10+delta glass ceramic

In this study, we have investigated the effects of Zn doping on structural and mechanical properties of Bi1.8Sr2Ca2Cu3.2-xZnxO10+delta ceramic samples with x = 0.0, 0.1, 0.5, 1.0. The prepared samples were characterized by using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), X-ray powder diffractometer (XRD) and static microhardness indenter. Surface morphology, orientation of grains and elemental composition analysis of the samples were investigated by SEM and EDS measurements, respectively. Texturing and lattice parameters a, b and c were determined from the XRD measurements. In this work we focused on Vickers microhardness measurements in order to characterize the mechanical properties. Experimental results of Vickers microhardness measurements were analyzed by using Meyer's law, the elastic/plastic deformation model, proportional sample resistance model (PSR), modified PSR model, Hays-Kendall (HK) approach and indentation induced cracking (IIC) model. According to the obtained results, HK approach is the most suitable model for the CZn00 sample showing indentation size effect behavior and IIC Model is the most suitable model for the CZn01, CZn05 and CZn10 samples showing reverse indentation size effect behavior

Structural and mechanical properties of ZnMgO nanoparticles

This study reports the effect of annealing temperature on the structure and mechanical properties of Zn0.95Mg0.05O bulk samples by using digital Vickers microhardness tester, X-ray diffraction analysis, scanning electron microscopy and electron dispersive X-ray measurements. The samples were prepared using Zn and Mg based alkoxed by the sol-gel technique and annealed at various temperatures (500, 600, 700 and 800 degrees C). Vickers microhardness, elastic modulus, yield strength and fracture toughness values of Zn0.95Mg0.05O bulk samples were separately calculated and compared with each other. The experimental results of hardness measurements were analyzed using Meyer's law, Proportional Specimen Resistance (PSR) and Elastic/Plastic Deformation (EPD) models and Hays-Kendall (HK) approach. Finally, it was seen that HK approach is the most successful model for the microhardness analysis of these materials. (C) 2013 Elsevier B.V. All rights reserved

Experimental and theoretical approaches on mechanical evaluation of Y123 system by Lu addition

Turkoz, Mustafa Burak/0000-0002-4127-7650; Yildirim, Gurcan/0000-0002-5177-3703; Ozturk, Ozgur/0000-0002-0391-5551WOS: 000321913000034This work is the continuation of a systematic study on the characterization of the Lu-added Y123 bulk superconducting materials prepared by the nitrate compounds and derivatives at 970 degrees C for 20 h. In this part, the effect of Lu inclusions on the physical and mechanical properties of the Y123 superconductors is examined with the aid of microhardness measurements performed at various applied loads in the range of 0.245-2.940 N. The microhardness measurement results allow us to determine the important mechanical characteristics such as Vickers microhardness, elastic (Young's) modulus, yield strength and fracture toughness values being responsible for the potential industrial applications. It is found that all the properties given above are strongly dependent upon the Lu concentration in the Y123 matrix. Especially, Vickers microhardness (H-nu) values of the samples studied in this work are found to suppressed considerably with the enhancement of the Lu addition in the system due to the degradation in the connectivity between superconducting grains. Moreover, the H-nu values of the pure Y123 sample are observed to increase with increasing the applied load whereas those of the Lu-doped superconducting materials are obtained to decrease with the load. In other words, the pure sample exhibits the reverse indentation size effect (RISE) behavior while the others obey the indentation size effect (ISE) feature, confirming the degradation in the mechanical properties with the Lu inclusions in the Y123 matrix. In addition, the microhardness measurement results are estimated using the 5 different models such as Meyer's law, proportional sample resistance model, elastic/plastic deformation model, Hays-Kendall (HK) approach and indentation-induced cracking (IIC) model. According to the results obtained from the simulations, of the mechanical analysis models, the Hays-Kendall (HK) approach is determined as the most successful model for the description of the mechanical properties of the Lu-doped superconducting materials (exhibiting the ISE behavior) where both the both the reversible (elastic) and irreversible (plastic) deformations are produced. On the other hand, the IIC model is found to be superior to other approaches for the pure sample (presenting the RISE feature) where the irreversible deformation becomes more and more dominant compared to the reversible deformation

Structural and mechanical properties of (Co/Mg) co-doped nano ZnO

The (Co/Mg) co-doped ZnO systems (ZnMgCoO) were synthesized as polycrystalline nanoparticles using the sol gel technique. The effects of Co/Mg co-addition to the structural and mechanical properties of ZnO nanoparticles were investigated. Microstructural properties, such as phases, crystal structures and grain sizes are characterized by using X-Ray Diffraction (XRD) analysis and Scanning Electron Microscope (SEM). The microhardness values of the samples were evaluated by the Vickers tester. In the samples of the Co > Mg ratio, Indentation Size Effect (ISE) behaviors were observed. On the other hand, in the samples of the Mg > Co ratio, Reverse Indentation Size Effect (RISE) was observed. These were analyzed in detail utilizing the models for materials hardness analysis found in literature. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved