Deformability of the Rare Earth Metal Modified Metastable-β Alloy Ti-15Mo

Authors: F. Brunke, L. Waalkes, C. Siemers

Abstract:

Due to reduced stiffness, research on second generation titanium alloys for implant applications, like the metastable β-titanium alloy Ti-15Mo, become more and more important in the recent years. The machinability of these alloys is generally poor leading to problems during implant production and comparably large production costs. Therefore, in the present study, Ti-15Mo was alloyed with 0.8 wt.-% of the rare earth metals lanthanum (Ti-15Mo+0.8La) and neodymium (Ti-15Mo+0.8Nd) to improve its machinability. Their microstructure consisted of a titanium matrix and micrometer-size particles of the rare earth metals and two of their oxides. The particles stabilized the microstructure as grain growth was minimized. As especially the ductility might be affected by the precipitates, the behavior of Ti-15Mo+0.8La and Ti- 15Mo+0.8Nd was investigated during static and dynamic deformation at elevated temperature to develop a processing route. The resulting mechanical properties (static strength and ductility) were similar in all investigated alloys.

Keywords: Ti-15Mo, Titanium alloys, Rare earth metals, Free-machining alloy.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1096767

References:

[1] M. Peters, C. Leyens, Titanium and Titanium Alloys, Wiley-VCH, Germany, 2002.
[2] M. Geetha, A.K. Singh, R. Asokamani, A.K. Gogia, Ti based biomaterials, the ultimate choice for orthopaedic implants – A Review, Prog. Mater. Sci. 54, 2009, pp. 397-425.
[3] A.G. Robling, A.B. Castillo, C.H. Turner, Biochemical and Molecular Regulation of Bone Remodeling, Annu. Rev. Biomed. Eng. 2006, Vol. 8 (2006), pp. 455-498.
[4] A.W. Bowen, Strength enhancement in a metastable β-titanium alloy: Ti-15Mo, Journal of Mat. Sci 12, 1977, pp. 1355-1360.
[5] W. Ho, Effect of Omega Phase on Mechanical Properties of Ti-Mo Alloys for Biomedical Applications, Journal of Med. and Bio. Eng., 28(1): pp. 47-51.
[6] G. Lütjering, Titanium, second ed., Springer Verlag, Germany, 2007.
[7] J. Donarchie, Titanium – A Technical Guide, ASM International, USA, 1988.
[8] M. Bäker, Finite Element Investigation of the Flow Stress Dependence of Chip Formation, J.Mater. Proc. Technol. 167, (2005),pp. 1-13.
[9] G. Sutter, G. List, Very high speed cutting of Ti-6Al-4V titanium alloy – change in morphology and mechanism of chip formation, Int. J. of Machine Tools and Manufacture, Vol. 66, 2013, pp. 37-43.
[10] M. Cotterell, G. Byrne, Dynamics of chip formation during orthogonal cutting of titanium alloy Ti-6Al-4V, CIRP Annals – Manufacturing Techn., Vol. 57, 2008, pp. 93-96.
[11] C. Siemers, P. Jencus, M. Bäker, J. Rösler, F. Feyerabend, A new free machining Titaniumalloy containing Lanthanum, in: Proc. 11th World Conference in Ti, Kyoto, Japan (2007), pp. 709-712.
[12] C. Siemers, F. Brunke, J. Laukart, M.S. Hussain, J. Rösler, K. Saksl, B. Zahra, Rare EarthMetals in Titanium Alloys – A Systematic Study, in: Proc. COM2012, Section Rare Earth Metals 2012, Niagara Falls, Canada, 2012, pp. 281-292.
[13] J. Laukart, C. Siemers, J. Rösler, Microstructure Evolution in Ti-Al-Mo- Fe-Mn-Cr-Cu Alloyscontaining Rare-Earth Metals, in: Proc. 12th World Conference on Ti, Beijing, China (2011), pp. 459-463.
[14] J. Laukart, C. Siemers, J. Rösler, Development of a castable, free- maching titanium alloy,Mater. Sci. Forum 690, (2011), pp. 3-6.
[15] F. Brunke, E. Meyer-Kornblum, C. Siemers, Influence of Iron on the Size and Distribution of Metallic LanthanumParticles in Free-machining Titanium Alloys Ti 6Al 7Nb xFe 0.9La, Mater. Sci. Forum 765, (2013), pp. 42-46
[16] N. Schell, A. King, F. Beckmann, H.U. Ruhnau, R. Kirchhof, R. Kiehn, M. Mueller, A. Schreyer, The High Energy Materials Science Beamline (HEMS) at PETRA III, Proceedings of the 10th International Conference on Synchrotron Radiation Instrumentation, Melbourne, Australia, September 27th – October 2nd , 2009, pp. 391 - 394.
[17] A.P. Hammersley, S.O. Svensson, M. Hanfland, A.N. Fitch, D. Häusermann, Two dimensional detector software: from real detector to idealised image or two theta scan, High Pressure Research 14 (4-5) (1996), pp. 235–248.
[18] B. H. Toby, "CMPR - a powder diffraction toolkit," Journal of Applied Crystallography 38, (2005), pp. 1040-1041.
[19] C. Siemers, F. Brunke, M. Stache, J. Laukart, B. Zahra, J. Rösler, P. Rockicki, K. Saksl, Advanced Titanium Alloys containing Micrometer- Size Particles, in: Proc. 12th World Conference on Ti, Beijing, China (2011), pp. 883-887.