SEARCH RESULT

Fe – 18Cr – 8Ni (at.%) stainless steels from elemental powders were synthesized by high energy mechanical alloying in a Spex™ 8000D Mixer/Mill. In order to investigate the alloying and transformation kinetics, milling time was ranged up to 30 hours at room temperature. The resultant powders were investigated as a function of milling time by x-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscope (SEM). The primary results have shown that the high energy milling induced martensitic transformation due to the severe plastic deformation as the martensite-to-austenite phase ratio was observed to increase with increasing milling time. The dependence of hardness on the microstructure was utilized to investigate the mechanical properties of synthesized powders. The research reported in this work was supported by TUBITAK under grant number 114M214.

International Iron & Steel Symposium
UDCS

Ahmet Burçin BATIBAY Hasan Kotan

Nanocrystalline stainless steels with solute additions are synthesized using high energy mechanical alloying. Microstructural evolutions as a function of alloy compositions and annealing temperatures are investigated using focused ion beam microscopy, transmission electron microscopy and in-situ and ex-situ X-ray diffraction techniques. The dependence of hardness on the microstructure is utilized to study the mechanical changes. The relative importance of composition and solute additions in various temperature ranges are discussed with respect to grain growth and phase stability. The research reported in this work was supported by TUBITAK under Grant number 114M214. The authors wish to thank TUBITAK for the support.

International Iron & Steel Symposium
UDCS

Hasan Kotan Ahmet Burçin BATIBAY

Titanium has low density (4.5 g / cm³), high specific strength, fracture toughness, fatigue strength, resistance to crack propagation, high toughness at low temperature and excellent corrosion resistance [1]. Pure Titanium is anti-toxic, anti-allergic and completely biocompatible [2]. Titanium has an allotropic structure [3]. Aluminum, tin, gallium and zirconium elements known as alpha stabilizers exhibit good properties at high temperatures. The elements of vanadium, molybdenum, niobium, tantalum, chromium which decrease phase transformation temperature are known as β stabilizer. When β-stabilizing elements were examined, they were usually found in brittle structures [4]. The creep resistance of α alloys is better than β alloys and α alloys are used for high temperature applications. β alloys can be heat treated and can not be applied to α alloys. The α + β alloys consist of a mixture of α and β phases, and these alloys have a good formability properties [5].

International Symposium on Light Alloys and Composite Materials
UHAKS

Seda Başer Erdem Kara Hasan Kotan Ahmet Burçin BATIBAY

Abstract Among metallic biomaterials, titanium (Ti) and alloys offer many advantages over other materials [1]. Pure Ti and Ti alloys are the most conspicuous group of biomedical implant materials due to their properties such as low elastic modulus, super biocompatibility, high strength / density ratio [2]. Commercially pure Ti and Ti-6Al-4V alloys are considered important biomaterials because they have many advantages such as these [3]. However, the high elastic modulus of pure Ti (102-105 GPa) compared to human bone tissues (4-30 GPa) can cause discrepancy between artificial implant materials and surrounding natural bones which restricts the use o Ti alloys. In addition, the Ti-6Al-4V alloy contains cytotoxic elements that can cause long-term health problems in the human body [6-7]. As a result, alloys without cytotoxic elements have been developed to overcome above the specified limitations [8]. In the majority of medical applications, Tantalum (Ta), Niobium (Nb), Tin (Sn) and their alloys have begun to be used. Nb has excellent corrosion resistance, good biocompatibility that do not cause a negative tissue reaction [9].

International Symposium on Light Alloys and Composite Materials
UHAKS

Erdem Kara Seda Başer Ahmet Burçin Batibay Hasan Kotan