Influence of Oxygen on Microstructures of Ti-Mo-Cr Alloy

Abstract:

In this study, the effect of oxygen addition on the microstructures of Ti-18%Mo-10%Cr alloy was investigated. The alloy was fabricated by a powder metallurgy method. The samples were subjected to sintering at 1300°C for 4 hours and furnace cooling. A Bo-Md method was initially applied for predicting stable phase. Calculation using the Bo-Md method showed that Ti-18%Mo-10%Cr alloy have bcc (β) phase at ambient temperature. All samples with various oxygen contents exhibited needle-like structures within equiaxed grains. The increase of oxygen content promoted formation of porosity in the α phase. Calculation of phase stability using JMatPro^TM showed that the decrease of β phase’s stability was not due to formation of the α phase on sintering, but due to promotion of nucleation and grain growth of diffusional α phase upon furnace cooling. It was also shown that vol.% of porosity of the alloy slightly increased with increasing oxygen content. Therefore, the increase of oxygen concentration could accelerate the formation of α phase and reduce the alloy’s density. The hardness increased as the oxygen concentration increased. The increase of the hardness might be due to combination of the solid solution hardening of oxygen and the precipitation hardening of α phase.

• Periodical: Advanced Materials Research (Volume 896)
• Pages: 613-616
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.896.613
• Online since: February 2014
• Authors: Junaidi Syarif*, Eko Kurniawan, Mohd Rasidi Rasani, Zainuddin Sajuri, Mohd Zaidi Omar, Sri Harjanto
• Keywords: Microstructure, Oxygen, Pores, Ti Alloys, β Phase

References

[1] J. Syarif, T.N. Rohmannudin, M.Z. Omar, Z. Sajuri and S. Harjanto, Stability of the beta phase in Ti-Mo-Cr alloy fabricated by powder metallurgy, J. Min. Metal. B (2013) accepted.

DOI: 10.2298/jmmb121024030s

[2] J. Syarif, E. Kurniawan, Z. Sajuri and M.Z. Omar, Influence of iron on phase stability and corrosion resistance of Ti-15%Cr alloy¸ Sains Malaysiana 42 (2013) accepted.

[3] N. Saunders, Z. Guo, X. Li, A.P. Miodownik and J. -P. Schille´, Using JMatPro to model materials properties and behavior, JOM 12 (2003) 60-65.

DOI: 10.1007/s11837-003-0013-2

[4] T.N. Rohmannudin, J. Syarif, M.Z. Omar, Z. Sajuri and A.R. Daud, Changes in phase stability on Ti-10 at. %Mo alloy by alloying elements, Intl. J. Mech. Mater. Eng. 4 (2009) 172-175.

[5] H.I. Aaronson, G. Spanos, R.A. Masamura, R.G. Vardiman, D.W. Moon, E.S.K. Menon and M.G. Hall, Sympathetic nucleation: an overview, Mater. Sci. Eng. B32 (1995) 107-123.

DOI: 10.1016/0921-5107(95)80022-0

[6] A.V. Dobromyslov, V.A. Elkin, Martensitic transformation and metastable β-phase in binary titanium alloys with d-metals of 4-6 periods, Scripta Mater. 44 (2001) 905-910.

DOI: 10.1016/s1359-6462(00)00694-1

[7] X.H. Min, K. Tsuzaki, S. Emura, K. Tsuchiya, Enhancement of uniform elongation in high strength Ti-Mo based alloys by combination of deformation modes, Mater. Sci Eng. A528 (2011) 4569-4578.

DOI: 10.1016/j.msea.2011.02.071