Structure-property correlations for Tib/sub 2/-based ceramics densified using active liquid metals

Conference · Thu Jan 01 04:00:00 EST 1981

OSTI ID:6320504

Tennery, V J; Finch, C B; Yust, C S; Clark, G W

It was demonstrated that TiB/sub 2/ powders can be sintered to near theoretical density with modest hot-pressing procedures when prescribed diboride particle sizes are used in conjunction with liquid sintering activation agents based on metals such as Ni. An important feature of the process which permits high sintered densities is exudation of excess Ni-rich liquid before porosity becomes isolated. Microcompositional data obtained from electron microscopy and the microstructural data indicate that nickel forms a liquid during hot pressing, and that some of the TiB/sub 2/ dissolves in the liquid to promote rapid diffusive transport of both Ti and B throughout the microstructure. Under optimum conditions, the TiB/sub 2/ particles essentially maintain their original size; the grain growth and microcracking characteristic of typical TiB/sub 2/ ceramics is, therefore, avoided. The flexure strength of the TiB/sub 2/ ceramics is about 750 MPa, but can be more than 850 MPa. The fracture toughness ranges between 6 and 8 MPa m/sup 1/2/. The Young modulus, Poisson ratio DPH and thermal diffusivity of ceramics densified using Ni-rich agents are the same as that for pure TiB/sub 2/. Experimental TiB cutting tools fabricated with Ni-rich sintering agents, performed well compared with commercial WC-Co based tools. 10 figures.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 6320504
• Report Number(s): CONF-810856-1; ON: DE81028069
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360203 -- Ceramics
Cermets
& Refractories-- Mechanical Properties
BORIDES
BORON COMPOUNDS
CUTTING TOOLS
DENSITY
ELEMENTS
FABRICATION
FLEXURAL STRENGTH
FRACTURE PROPERTIES
GRAIN GROWTH
HARDNESS
HOT PRESSING
MATERIALS WORKING
MECHANICAL PROPERTIES
METALS
NICKEL
PARTICLE SIZE
PERFORMANCE
PHYSICAL PROPERTIES
POISSON RATIO
PRESSING
SINTERING
SIZE
THERMAL DIFFUSIVITY
THERMODYNAMIC PROPERTIES
TITANIUM BORIDES
TITANIUM COMPOUNDS
TOOLS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
YOUNG MODULUS