%0 journal article
%@ 2352-9407
%A Xu, P.,Pyczak, F.,Yan, M.,Limberg, W.,Willumeit-Römer, R.,Ebel, T.

%D 2020
%J Applied Materials Today
%N 
%P 100630 
%R doi:10.1016/j.apmt.2020.100630
%T Tensile toughening of powder-injection-molded β Ti-Nb-Zr biomaterials by adjusting TiC particle distribution from aligned to dispersed pattern
%U https://doi.org/10.1016/j.apmt.2020.100630
 
%X The powder metallurgically produced β titanium alloys have long been plagued by high impurity contamination. One of them is the carbon contamination of binder-based powder technologies that originates from the sintering atmosphere, the debinding process and the starting powders. In general, a normal carbon residual of binder-based powder technologies is capable of incurring the formation of aligned TiCx particles along prior β grain boundaries (GB-TiCx) in most classes of β titanium. Premature intergranular fracture of materials invariably ensues during plastic deformation, which hinders their commercialization in structural applications. A novel toughening strategy by regulating TiCx precipitation evolution and resultantly adjusting particle distribution is suggested. In this study, biotolerant metastable β Ti-Nb-Zr alloys containing 0.05 wt% standard carbon residual and consequently 0.5 vol% in situ synthesized TiCx particles were fabricated via powder injection molding. Synchrotron radiation identified that two separate TiCx precipitation-type reactions occurred at β phase region and α/β region. In a narrow temperature range between these two precipitation reactions, dissolution of carbides is observed just below α/β transus. Yttrium addition can postpone TiCx precipitation. On the basis of those mechanisms, adjusting TiCx particle distribution is proposed for the first time, specifically a combination of yttrium addition (Y) and carbide spheroidization reprecipitation annealing (CSRA). As a result, aligned GB-TiCx particles were adjusted to dispersed intragranular TiCx particles. An apparent toughening effect (≈113% increment reaching εf = 8.3%) was achieved after TiCx redistribution, while non-optimally aligned TiCx pattern seriously limited tensile toughness of materials by two negative crack propagation modes. Here, the mechanisms of TiCx redistribution behavior and its toughening are elucidated systematically.