Synthesis of in situ TiB{sub 2}/TiN Ceramic matrix composites from dense BN-Ti and BN-Ti-Ni powder blends

Journal Article · Thu Aug 01 00:00:00 EDT 1996 · Metallurgical Transactions, A

OSTI ID:282250

Olevsky, F; Mogilevsky, P; Gutmanas, E Y; Gotman, I

In the present research, near-net-shape in situ TiB{sub 2}/TiN and TiB{sub 2}/TiN/Ni composites were fabricated from cold-sintered BN/Ti and BN/Ti/Ni powder blends by pressureless displacement reaction synthesis or thermal explosion under pressure. In both approaches, the processing or preheating temperatures ({le}1,200 C) were considerably lower than those typical of current methods used for the processing/consolidation of ceramic matrix composites. Microstructural characterization of the materials obtained was performed using X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Mechanical properties were evaluated by measuring microhardness, fracture toughness, and three-point bending strength. Application of a moderate external pressure ({le}250 MPa) during self-propagating synthesis (SHS) synthesis was shown to be sufficient to ensure full density of the TiB{sub 2}TiN/Ni composite. The entire procedure of thermal explosion under pressure could be performed in open air without noticeable oxidation damage to the final product. The high fracture toughness of the in situ synthesized TiB{sub 2}/TiN/Ni composite (20.5 MPa{radical}m) indicated that the finely dispersed ductile Ni phase was effective in dissipating the energy of cracks propagating in the ceramic matrix.

• OSTI ID: 282250
• Report Number(s): CONF-950201-; ISSN 0360-2133; TRN: IM9638%%48
• Journal Information: Metallurgical Transactions, A, Vol. 27, Issue 8; Conference: Annual meeting and exhibition of the Minerals, Metals and Materials Society (TMS), Las Vegas, NV (United States), 12-16 Feb 1995; Other Information: PBD: Aug 1996
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COMPOSITE MATERIALS
SYNTHESIS
MICROSTRUCTURE
MECHANICAL PROPERTIES
TITANIUM BORIDES
TITANIUM NITRIDES
NICKEL
BORON NITRIDES
TITANIUM
CHEMICAL REACTIONS
PRESSURE DEPENDENCE
X-RAY DIFFRACTION
SCANNING ELECTRON MICROSCOPY
TRANSMISSION ELECTRON MICROSCOPY
MICROHARDNESS
FRACTURE PROPERTIES
FLEXURAL STRENGTH