Near-net-shape Fabrication of Ni(x)Al(y) – TiC Cermets by Binder Jet Additive Manufacturing and Pressure-less Melt Infiltration

Author

Joshua Michael Arnold, University of Tennessee

Date of Award

8-2018

Degree Type

Thesis

Degree Name

Master of Science

Major

Materials Science and Engineering

Major Professor

Sudarsanam Suresh Babu

Committee Members

Brett G. Compton, Claudia J. Rawn, Haixuan Xu

Abstract

Binder jet additive manufacturing effectively replaces preform preparation by traditional powder metallurgy methods and allows more complex geometries to be potentially fabricated. The use of a pressure-less melt infiltration technique provides a method of achieving a fully dense composite in a near-net-shape fashion, cost effective and scalable. TiC preforms (15 x 15 x 10/7.5 mm) were fabricated via Binder Jet Additive Manufacturing and then infiltrated by NiAl₃ and Ni₃Al using a pressure-less melt infiltration technique. Two compositions, Ni₃Al and NiAl₃, were used as infiltrant materials in order to compare wetting behavior and infiltration kinetics.A stark difference in shape retention between Ni₃Al and NiAl₃ infiltrated preforms was observed after infiltration. It was found that the TiC particles in the as printed preform were arranged in an interconnected network structure as a result of the binder jet process and/or sintering step and is responsible for maintaining structural integrity of the printed preform. TiC dissolution by liquid Ni₃Al was significant enough to disband this network structure and force particle rearrangement and lead to poor shape retention. Conversely, TiC particle rearrangement did not occur during infiltration of the Al-rich NiAl₃ alloy and thus the network structure remained intact leading to excellent shape retention of the infiltrated preform.It was found NiAl₃ exhibits a complex melting and solidification behavior where an Al-rich phase segregates heavily from the melted material. The presence of an Alrich inter-particle matrix phase indicates the possibility of a “metered” infiltration process where multiple liquid phases of variant compositions infiltrate the “macro” and “micro” capillaries of the TiC preform in a staggered fashion. The composition and time of infiltration remains unknown and a topic of future work. Additionally, Thermodynamic simulation predicts a reaction at the TiC interface by liquid NiAl₃ to form Al₄C₃, with an interfacial reaction product potentially explaining the lack of TiC dissolution and volumetric shrinkage during and after infiltration by NiAl₃.

Recommended Citation

Arnold, Joshua Michael, "Near-net-shape Fabrication of Ni(x)Al(y) – TiC Cermets by Binder Jet Additive Manufacturing and Pressure-less Melt Infiltration. " Master's Thesis, University of Tennessee, 2018.
https://trace.tennessee.edu/utk_gradthes/5113