Trace Carbon in Biomedical Beta-Titanium Alloys: Recent Progress

Abstract

Owing to their relatively low Young's modulus, high strength, good resistance to corrosion and excellent biocompatibility, β-titanium (Ti) alloys have shown great potential for biomedical applications. In β-Ti alloys, carbon can exist in the form of titanium carbide (TiC x) as well as interstitial atoms. The TiC binary phase diagram predicts a minimum carbon solubility value of 0.08 wt.% in β-Ti, which has been used as the carbon limit for a variety of β-Ti alloys. However, noticeable grain boundary TiC x particles have been observed in β-Ti alloys at impurity levels of carbon well 2 below the predicted 0.08 wt.%. This review focuses its attention on the trace carbon (≤ 0.08 wt.%) in biomedical β-Ti alloys containing niobium (Nb) and molybdenum (Mo), and discusses the nature and precipitation mechanism of the TiC x particles in these alloys.

A Review on Material Extrusion Additive Manufacturing of Metal and How It Compares with Metal Injection Moulding

“…The furnace atmosphere is one of the critical issues in the sintering process that influences the material properties, especially for Ti alloys, which are highly reactive with carbon, oxygen, nitrogen and hydrogen. Excessive impurity pick-up during debinding and sintering reduces elongation [124] owing to the formation α-phase by oxygen picking in CP-Ti [102] and the formation of brittle TiC generated by excessive carbon in beta Ti alloys [11,187,188]. As observed from Table 5, atmospheres suitable for sintering of stainless steel are H 2 , N 2 , Ar and vacuum, but the atmosphere for the sintering of CP-Ti and Ti-6Al-4V is limited to Ar or vacuum.…”

Metal injection moulding of titanium and titanium alloys: Challenges and recent development

“…[18,24,45,[52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69] Prevention of carbon contamination is much easier to achieve than it is for oxygen by using a flow of high purity argon cover gas during the debinding process. It is necessary to limit the carbon content to less than 0.08wt% in order to avoid titanium carbide formation within the structure [70]. If present, titanium carbides may reduce the elongation and fatigue properties, reduce corrosion resistance and enhance the Young's modules of Ti alloys [70], and accordingly, their formation should be generally avoided in MIM-Ti components.…”

“…It is necessary to limit the carbon content to less than 0.08wt% in order to avoid titanium carbide formation within the structure [70]. If present, titanium carbides may reduce the elongation and fatigue properties, reduce corrosion resistance and enhance the Young's modules of Ti alloys [70], and accordingly, their formation should be generally avoided in MIM-Ti components. However, in some novel studies, the positive behaviour of extra carbon has been exploited in MIM-Ti.…”

“…Tables: Table 1: A summary of some published data on MIM of Ti and selected Ti-alloys during last 20 years [18,24,45,[52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70] [74] [75]…”

Control of titanium carbide in the alloys

“…As reported by multiple authors (Y. G. Li et al, 2001;Zhang S. et al, 2016;Zhao, D. et al, 2015), both the mechanical properties and microstructures of Titanium alloys are drastically influenced by the inclusion of carbon particles due to the formation of Titanium carbide precipitates ( ).…”