title: Impacts of trace carbon on the microstructure of as-sintered biomedical Ti-15Mo alloy and reassessment of the maximum carbon limit.
abstract: The formation of grain boundary (GB) brittle carbides with a complex three-dimensional (3-D) morphology can be detrimental to both the fatigue properties and corrosion resistance of a biomedical titanium alloy. A detailed microscopic study has been performed on an as-sintered biomedical Ti-15Mo (in wt.%) alloy containing 0.032 wt.% C. A noticeable presence of a carbon-enriched phase has been observed along the GB, although the carbon content is well below the maximum carbon limit of 0.1 wt.% specified by ASTM Standard F2066. Transmission electron microscopy (TEM) identified that the carbon-enriched phase is face-centred cubic Ti2C. 3-D tomography reconstruction revealed that the Ti2C structure has morphology similar to primary α-Ti. Nanoindentation confirmed the high hardness and high Young's modulus of the GB Ti2C phase. To avoid GB carbide formation in Ti-15Mo, the carbon content should be limited to 0.006 wt.% by Thermo-Calc predictions. Similar analyses and characterization of the carbide formation in biomedical unalloyed Ti, Ti-6Al-4V and Ti-16Nb have also been performed.
authors.affiliation: The University of Queensland, Queensland Centre for Advanced Materials Processing and Manufacturing (AMPAM), School of Mechanical and Mining Engineering, Brisbane, Qld 4072, Australia; The University of Queensland, School of Mechanical and Mining Engineering, ARC Centre of Excellence for Design in Light Metals, Brisbane, Qld 4072, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Yan
authors.affiliation: The University of Queensland, School of Mechanical and Mining Engineering, ARC Centre of Excellence for Design in Light Metals, Brisbane, Qld 4072, Australia. Electronic address: ma.qian@uq.edu.au.
authors.forename: M
authors.initials: M
authors.lastname: Qian
authors.affiliation: Electron Microscopy Unit, University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: C
authors.initials: C
authors.lastname: Kong
authors.affiliation: The University of Queensland, Queensland Centre for Advanced Materials Processing and Manufacturing (AMPAM), School of Mechanical and Mining Engineering, Brisbane, Qld 4072, Australia. Electronic address: m.dargusch@uq.edu.au.
authors.forename: M S
authors.initials: MS
authors.lastname: Dargusch
mesh_terms: D000497:Alloys / Q000737:chemistry*; D002244:Carbon / Q000032:analysis*; D021621:Imaging, Three-Dimensional; D055595:Mechanical Phenomena; D008855:Microscopy, Electron, Scanning; D044367:Phase Transition
chemical_list: D000497:Alloys; C525450:titanium molybdenum alloy; D002244:Carbon
keywords: 3-D tomography; Biomedical titanium alloys; Carbon limit; Titanium carbides