DIFFUSION OF Nb WITH Cr, Fe, Ni, Mo, AND STAINLESS STEEL

Technical Report · Mon Feb 01 04:00:00 EST 1960

OSTI ID:4174923

Birks, L S; Seebold, R E

Diffusion couples were prepared at about 1100 deg C from pure Nb and several compositions of stainless steel and also with each of the components of the steel, namely, Cr, Fe, Ni, and Mo. Using the electron probe microanalyzer to measure the composition across these diffusion zones, intermediate phases of stoichiometric composition were found for each of the binaries. In Nb-Cr diffusion the phases NbCr/sub 2/ and NbCr/sub 7/ were always present, and after long heating times NbCr plus excess Nb in solid solution was observed as well. In Nb-Fe diffusion the intermediate phase was NbFe/sub 2/ plus excess Fe in solid solution, but there were isolated Nb-rich compounds far out into the iron, pending on the impurity composition of the iron. Nb-Ni couples often melted near 1100 deg C, although the eutectic composition is given as 1175 deg C in some of the literatare. Below 1095 deg C NbNi plus excess Nb in solid solution was observed and Nb/sub 2/Ni precipitated in the NbNi matrix on cooling. Above 1195 deg C, at near melting, rapid diffusion led to zones as long as 1400 microns with NbNn precipitating in an NbNi matrix on cooling. Nb and Mo were miscible at all compositions, and the diffusion coefficient ranged from 3 to 8 x 10/sup -11/ cm/ sup 2//sec. Diffusing Nb with stainless steel showed a main zone of about 40% Nb, 40% Fe, 8% Cr, and 6% Ni (all as weight per cent) and was speculated to contain a mixture of NbFe/sub 2/, NbCr/sub 2/, and NbNi. A small region near the Nb side of the diffusion zone was speculated to contain a mixture of NbFe/sub 2/, NbCr, and Nb/sub 2/Ni. (auth)

• Research Organization: Naval Research Lab., Washington, D.C.
• NSA Number: NSA-14-012940
• OSTI ID: 4174923
• Report Number(s): NRL-5461
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

CHROMIUM ALLOYS
COOLING
DIFFUSION
ELECTRON MICROSCOPY
EUTECTICS
HIGH TEMPERATURE
IMPURITIES
INTERMETALLIC COMPOUNDS
IRON ALLOYS
MEASURED VALUES
MELTING
METALS, CERAMICS, AND MATERIALS
MIXING
MOLYBDENUM ALLOYS
NICKEL ALLOYS
NIOBIUM ALLOYS
PHASE DIAGRAMS
PRECIPITATION
PREPARATION
SOLID SOLUTIONS
STAINLESS STEELS
ZONES