skip to main content

SciTech ConnectSciTech Connect

Title: Processing and Oxidation Behavior of Nb-Si-B Intermetallics

Single phase materials of {alpha}-Nb{sub 5}Si{sub 3}, Nb{sub 5}(Si,B){sub 3} (T2) and Nb{sub 5}Si{sub 3}B{sub x} (D8{sub 8}) in the Nb-Si-B system were prepared by powder metallurgy processing. T2 was almost fully dense, while {alpha}-Nb{sub 5}Si{sub 3} and D8{sub 8} were porous after sintering at 1900 C for 2 hours. The lattice parameters of T2 decreased linearly with the substitution of B for Si. Isothermal oxidation testing at 1000 C in flowing air indicated that the oxidation resistances of T2 and D8{sub 8} are much better than {alpha}-Nb{sub 5}Si{sub 3}, but still extremely poor compared to the boron-modified Mo{sub 5}Si{sub 3}. Extensive cracking in the oxide scale and matrix were observed and arose from the volume expansion associated with the formation of Nb{sub 2}O{sub 5} and boron-containing silica glass.
Authors:
; ; ;
Publication Date:
OSTI Identifier:
832901
Report Number(s):
IS-M 924
TRN: US200430%%914
DOE Contract Number:
W-7405-Eng-82
Resource Type:
Conference
Resource Relation:
Conference: Conference title not supplied, Conference location not supplied, Conference dates not supplied; Other Information: PBD: 30 Sep 2004
Research Org:
Ames Laboratory, Ames, IA (US)
Sponsoring Org:
USDOE Office of Science (SC) (US)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; NIOBIUM BORIDES; SILICON BORIDES; GLASS; LATTICE PARAMETERS; OXIDATION; POWDER METALLURGY; SINTERING; NIOBIUM SILICIDES; CRACK PROPAGATION; OXIDES