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Microstructure and corrosion behavior of porous coatings on titanium alloy by vacuum‐brazed method
Author(s) -
Lee T.M.,
Chang E.,
Yen C.H.
Publication year - 2006
Publication title -
journal of biomedical materials research part b: applied biomaterials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.665
H-Index - 108
eISSN - 1552-4981
pISSN - 1552-4973
DOI - 10.1002/jbm.b.30440
Subject(s) - brazing , materials science , microstructure , metallurgy , alloy , sintering , intergranular corrosion , corrosion , filler metal , titanium , scanning electron microscope , titanium alloy , intermetallic , substrate (aquarium) , composite material , welding , oceanography , arc welding , geology
Abstract The microstructural evolution and electrochemical characteristics of brazed porous‐coated Ti‐6Al‐4V alloy were analyzed and compared with respect to the conventionally 1300°C sintering method. The titanium filler metal of low‐melting‐point (934°C) Ti‐15Cu‐15Ni was used to braze commercially pure (CP) titanium beads onto the substrate of Ti‐6Al‐4V alloy at 970°C for 2 and 8 h. Optical microscopy, scanning and transmission electron microscopy, and X‐ray diffractometry (XRD) were used to characterize the microstructure and phase of the brazed metal; also, the potentiostat was used for corrosion study. Experimental results indicate that the bead/substrate contact interface of the 970°C brazed specimens show larger contact area and higher radius curvature in comparison with 1300°C sintering method. The microstructure of brazed specimens shows the Widmanstätten structure in the brazed zone and equiaxed α plus intergranular β in the Ti‐6Al‐4V substrate. The intermetallic Ti 2 Ni phase existing in the prior filler metal diminishes, while the Ti 2 Cu phase can be identified for the substrate at 970 for 2 h, but the latter phase decrease with time. In Hank's solution at 37°C, the corrosion rates of the 1300°C sintering and the 970°C brazed samples are similar at corrosion potential ( E corr ) in potentiodynamic test, and the value of E corr for the brazed sample is noble to the sintering samples. The current densities of the brazed specimens do not exceed 100 μA/cm 2 at 3.5 V (SCE). These results suggest that the vacuum‐brazed method exhibits the potentiality to manufacture the porous‐coated specimens for biomedical application. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006