1. Nevsehir University , Faculty of Engineering and Architecture, Department of Materials Engineering , Nevsehir – Turkey
2. Bartin University , Faculty of Engineering, Dept. of Metallurgical and Materials Engineering , Bartin – Turkey
3. Erciyes University , Faculty of Engineering, Dept. of Material Science and Engineering, Kayseri – Turkey; e-mail: , Fax: +90 352 437 49 31