Transient liquid-phase infiltration of a powder-metal skeleton

Transient Liquid-Phase Infiltration (TLI) is a new method for densifying a powder-metal skeleton that produces a final part of homogeneous composition without significant dimensional change, unlike traditional infiltration and full-density sintering. Fabrication of direct metal parts with complex geometry is possible using TLI in conjunction with Solid Freeform Fabrication (SFF) processes such as Three-Dimensional Printing, which produce net-shape skeletons of powdered metal directly from CAD models. The infiltrant used in TLI is typically composed of the skeleton material plus a melting point depressant in order to facilitate homogenization after the liquid metal fills the void space. Parts over 20 cm tall with final compositions of Ni-4wt%Si and Ni-40wt%Cu were made by TLI from powder skeletons of pure nickel. Tensile tests after HIP treatment compared favorably with cast material of the same composition. A basic understanding of the materials system requirements for TLI and the role of various parameters was developed using nickel-silicon and nickel-copper as test cases. Upon introduction of the liquid infiltrant to the skeleton, the melting point depressant begins to diffuse into the skeleton causing isothermal solidification of the infiltrant. This solidification chokes theflow of liquid and can limit the infiltration distance.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2002

Author dc:creator

• Lorenz, Adam Michael, 1974-

Advisor dc:contributor.advisor

• Emanuel Sachs.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/16880

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/16880