J. Mater. Sci. Technol. ›› 2015, Vol. 31 ›› Issue (2): 148-152.DOI: 10.1016/j.jmst.2014.09.004

• Orginal Article • Previous Articles     Next Articles

Effect of Annealing on Microstructure and Microhardness of Co-Fe-Ni-Ta-B-Si Bulk Metallic Glass

Aytekin Hitit1, Merve Geçgin2, Pelin Öztürk1   

  1. 1 Department of Materials Science and Engineering, Afyon Kocatepe University, Afyonkarahisar 03200, Turkey; 2 Department of Materials Science and Engineering, Anadolu University, Eski?ehir 26555, Turkey
  • Received:2014-04-17 Online:2015-02-20 Published:2015-07-23
  • Contact: Corresponding author. Ph.D; Tel./Fax: +90 272 2281441.E-mail address: hitit@aku.edu.tr (A. Hitit).
  • Supported by:

    This study was supported by the Scientific and Technological Research Council of Turkey.

Abstract:

Effects of annealing temperature and time on microstructure and microhardness of Co41Ni2Fe20Ta5.5B26.5Si5 amorphous alloy have been investigated. Microhardness of the as-cast alloy is found to be 1170 HV. The maximum microhardness,1798 HV, is achieved after annealing the amorphous alloy at 1250 K for 10 min. Examination of the microstructure reveals that (Co,Fe)2B, (Co,Fe)21Ta2B6 and (Co,Fe)16Ta6Si7 phases precipitate in the matrix after annealing. Intrinsic hardness and Hall-Petch coefficients of the precipitates indicate that high hardness values result from precipitation of (Co,Fe)2B and (Co,Fe)21Ta2B6 phases. It is also observed that increasing the annealing time results in the decrease in microhardness values because of the increase in particle sizes of the precipitates.

Key words: Metallic glass, Annealing, Microhardness