Low-melting-point titanium-base brazing alloys. Part 2: Characteristics of brazing Ti-21Ni-14Cu on Ti-6Al-4V substrate

Journal Article · Mon Dec 01 04:00:00 EST 1997 · Journal of Materials Engineering and Performance

DOI:https://doi.org/10.1007/s11665-997-0084-2· OSTI ID:561919

Chang, E; Chen, C H ^[1]

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1. National Cheng-Kung Univ., Tainan (Taiwan, Province of China). Dept. of Materials Science and Engineering

Filler metal of a low-melting-point (917 C) Ti-21Ni-14Cu was brazed onto the substrate of Ti-6Al-4V alloy at 960 C for 2, 4, and 8 h to investigate the microstructural evolution and electrochemical characteristics of the brazed metal as a function of the period of brazing time. Optical microscopy, scanning and transmission electron microscopy, and x-ray diffractometry were used to characterize the microstructure and phase of the brazed metal; also, the potentiostat was used for corrosion study. Experimental results indicate that diffusion of copper and nickel from the filler metal into the equiaxed {alpha} plus intergranular {beta} structure of Ti-6Al-4V substrate causes the lamellar Widmanstaetten structure to form. The intermetallic Ti{sub 2}Ni phase existing in the prior filler metal diminishes, while the Ti{sub 2}Cu phase can be identified for the metal brazed at 960 C for 2 h, but the latter phase decreases with time. Advantage might be taken from the evidence of faster diffusion of nickel than copper along the {beta} phase to the substrate. In deaerated Hank`s solution, corrosion potential, corrosion current density, and critical potential for active-to-passive transition decrease while the passivation range broadens with the period of brazing time. However, all the brazed metals, immersed for different periods in oxygen-saturated Hank`s solution, show similar corrosion behavior, irrespective of the brazing time.

• Sponsoring Organization: USDOE
• OSTI ID: 561919
• Journal Information: Journal of Materials Engineering and Performance, Journal Name: Journal of Materials Engineering and Performance Journal Issue: 6 Vol. 6; ISSN 1059-9495; ISSN JMEPEG
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BRAZING
COPPER ALLOYS
CORROSION RESISTANCE
DIFFUSION
ELECTROCHEMISTRY
INTERMETALLIC COMPOUNDS
MICROSTRUCTURE
NICKEL ALLOYS
TEMPERATURE RANGE 1000-4000 K
TIME DEPENDENCE
TITANIUM ALLOYS
WIDMANSTAETTEN STRUCTURE
X-RAY DIFFRACTION