Microstructural investigations of rapidly solidified al-co-y alloys

Avar B. | Gogebakan M. | Tarakci M. | Gencer Y. | Kerli S.

Article | 2013 | Advances in Materials Science and Engineering2013

The alloys with different compositions in the Al-rich corner of the Al-Co-Y ternary system were prepared by conventional casting and further processed by melt-spinning technique. The microstructure and the thermal behavior of the alloys were analyzed by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and differential thermal analysis (DTA). It was found that only rapidly solidified Al 85Co7Y8 alloy exhibited the best glass forming ability (GFA) and a fully amorphous structure. Besides, Al85Co 13Y2 and Al85Co2Y13 alloy ribbons were fully crystalline, whereas Al85Co10Y 5 a . . .nd Al85Co5Y10 alloy ribbons consisted of some crystalline phases within an amorphous matrix. The SEM results showed the same trend that the crystalline phase fraction decreases with the approaching into best glass former. From DSC results, only Al 85Co7Y8 amorphous alloy exhibited a glass transition temperature (Tg) at 569 K, and its supercooled liquid region (?Tx=Tx-Tg) was found to be 17 K. Moreover, other calculated GFA parameters for this alloy system were also discussed. © 2013 B. Avar et al Daha fazlası Daha az

A new appliance for improving the miniscrew stability

Özkalaycı, Nurhat | Yetmez, Mehmet

Article | 2016 | Advances in Materials Science and Engineering2016

The aim of this study is to present a new appliance called stability leg designed as an additional anchorage providing device for increasing primary stability of orthodontic miniscrew. For this purpose, two finite element models (FEMs) with two different cortical layer thicknesses of 1 mm and 2 mm are considered. In order to achieve the stability analysis, these two main models, namely, Model I and Model II, are divided into subgroups according to stability leg lengths. Two types of forces are considered. (1) First force is a constant force of 1 N which is applied to all two models. (2) Second force is defined in the range of 1-4 N. . . . Each of 1, 2.5, and 4 N of the second force is applied with a position angle ranging from 34° to 44°. Results show that stability of a miniscrew with 5 mm leg increases primary stability of the miniscrew. © 2016 Nurhat Ozkalayci and Mehmet Yetmez Daha fazlası Daha az

Studies on characterization of bovine hydroxyapatite/CaTiO3 biocomposites

Öztürk, Suat | Yetmez, Mehmet

Article | 2016 | Advances in Materials Science and Engineering2016

Sintering effects and mechanical properties of bovine hydroxyapatite/CaTiO3 composites are investigated for different CaTiO3 ratios. Results indicate that densities of the biocomposites increase while total porosities of those decrease with increasing sintering temperature. Moreover, modulus of elasticity and microhardness increase with increasing sintering temperature. However, values of both toughness and fracture toughness of the biocomposites generally rise with increasing sintering temperature except for 1300°C. © 2016 Suat Ozturk and Mehmet Yetmez.

Sintering behavior and mechanical properties of biphasic calcium phosphate ceramics

Yetmez, Mehmet

Article | 2014 | Advances in Materials Science and Engineering2014

The sintering behavior and the mechanical properties of a mechanical mixture of hydroxyapatite and tricalcium phosphate (BCP) ceramics with the composition of 30% HA and 70% TCP are experimentally investigated in the temperature range between 1000°C and 1300°C. The results show that consolidation, grain growth, and Vickers hardness generally increase with increasing sintering temperature up to 1200°C. However, microstructure observation indicates that cracks are formed along the grain boundaries as well as in the bulk of the grains after sintering at 1200°C. Moreover, the best values of compressive strength, modulus of elasticity, a . . .nd toughness are achieved in the samples sintered at 1100°C. These properties at 1100°C decay with sintering at 1200°C and increase again after sintering at 1300°C. © 2014 Mehmet Yetmez Daha fazlası Daha az

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