Ductile phase toughening of molybdenum disilicide using low pressure plasma spraying

Technical Report · Sun Dec 01 04:00:00 EST 1991

OSTI ID:6270305

Castro, R G

The lack of ductility associated with molybdenum disilicide (MoSi{sub 2}) and other intermetallic compounds at ambient temperature has prompted investigations into new processing techniques and toughening mechanisms in order to impart some degree of fracture toughness to these inherently brittle materials. In this investigation, low pressure plasma spraying was used as a fabrication method to produce spray formed deposits of MoSi{sub 2} and discontinuous ductile reinforced MoSi{sub 2}-tantalum composites. Fracture toughness (K{sub 1C}) measurements of MoSi{sub 2} and the ductile reinforced composites which contained 10 and 20 weight percent of a discontinuous tantalum lamella reinforcement were measured in both the as-sprayed condition and after hot isostatically pressing at 1200{degrees}/206 MPa for 1 hr. Two fracture toughness tests were done on each sample, an indentation technique which ranked the relative fracture toughness (K{sub 1C}) of the sprayed deposits, and a chevron 4-pt bend test which gave a better quantitative measurement of the plane-strain fracture toughness of the sprayed deposits. Results of the fracture toughness tests have shown fracture toughness increases on the order of 200% over conventional hot pressed MoSi{sub 2}. In addition, a marked anisotropy in fracture toughness was observed to occur in the sprayed formed deposits due to the layer splat structure produced by the low pressure plasma spray process. 62 refs., 44 figs., 7 tabs.

• Research Organization: Los Alamos National Lab., NM (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6270305
• Report Number(s): LA-12220-T; ON: DE92003737
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201 -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
ALLOYS
CRYSTAL STRUCTURE
DEPOSITION
DUCTILITY
FABRICATION
FRACTOGRAPHY
FRACTURE PROPERTIES
HOT PRESSING
INTERMETALLIC COMPOUNDS
MATERIALS WORKING
MECHANICAL PROPERTIES
MICROSTRUCTURE
MOLYBDENUM COMPOUNDS
MOLYBDENUM SILICIDES
PHASE TRANSFORMATIONS
PLASMA ARC SPRAYING
PRESSING
REFRACTORY METAL COMPOUNDS
SILICIDES
SILICON COMPOUNDS
SOLIDIFICATION
SPRAY COATING
SURFACE COATING
TENSILE PROPERTIES
TRANSITION ELEMENT COMPOUNDS