TY - THES

T1 - Carbide precipitates in as-sintered and heat treated Ti-22Nb-(10Zr-xB) alloys processed by metal injection molding

AU - Ebner, Sandra

N1 - embargoed until null

PY - 2016

Y1 - 2016

N2 - Ti-Nb alloys present an excellent choice for biomedical applications due to their low Young’s modulus and very good biocompatibility. Though, the fabrication of these alloys using metal injection molding (MIM) turned out to lead to the formation of titanium carbides that adversely affects the ductility. Aim of this work was a reduction of the carbide precipitates to improve the mechanical properties. Therefore, different compositions of Ti-22Nb-(10Zr-xB) with x=0, 0.3 and 0.5 (m.%) were consolidated by MIM and subsequently heat treated. The carbon and oxygen content was determined and density was measured. Further investigations included optical microscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). It could be shown that both zirconium and boron are influencing the sintering process and, consequently, porosity increases and grain size decreases. Moreover, the addition of boron leads to the formation of titanium borides that are non-homogenous distributed in the matrix. A reduction of titanium carbides was observed with the addition of zirconium and boron. The heat treatments influenced the amount of titanium carbides differently, where the precipitation of carbides could be nearly fully suppressed by water quenching.

AB - Ti-Nb alloys present an excellent choice for biomedical applications due to their low Young’s modulus and very good biocompatibility. Though, the fabrication of these alloys using metal injection molding (MIM) turned out to lead to the formation of titanium carbides that adversely affects the ductility. Aim of this work was a reduction of the carbide precipitates to improve the mechanical properties. Therefore, different compositions of Ti-22Nb-(10Zr-xB) with x=0, 0.3 and 0.5 (m.%) were consolidated by MIM and subsequently heat treated. The carbon and oxygen content was determined and density was measured. Further investigations included optical microscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). It could be shown that both zirconium and boron are influencing the sintering process and, consequently, porosity increases and grain size decreases. Moreover, the addition of boron leads to the formation of titanium borides that are non-homogenous distributed in the matrix. A reduction of titanium carbides was observed with the addition of zirconium and boron. The heat treatments influenced the amount of titanium carbides differently, where the precipitation of carbides could be nearly fully suppressed by water quenching.

KW - Titan

KW - beta-Titanlegierung

KW - Metallpulverspritzgießen

KW - MIM

KW - Titankarbide

KW - Wärmebehandlung

KW - titanium

KW - beta-alloy

KW - metal injection molding

KW - titanium carbide

KW - heat treatment

M3 - Diploma Thesis

ER -