Open AccessDIFFUSION KINETICS STUDIES IN THE Al-Ni-U SYSTEM
Author(s) -
Harlow. R.A.,
Oscar Gamba
Publication year - 1963
Language(s) - English
Resource type - Reports
DOI - 10.2172/4154205
Subject(s) - materials science , isothermal process , annealing (glass) , penetration (warfare) , nickel , alloy , metallurgy , aluminium , cladding (metalworking) , atomic diffusion , kinetics , analytical chemistry (journal) , composite material , thermodynamics , chemistry , physics , quantum mechanics , chromatography , operations research , engineering
A diffusion couple technique was developed and standardized for the purpose of obtaining meaningful data regarding the diffusion kinetics of the Al-- Ni--U system. The technique entailed hot pressing under a dynamic vacuum and subsequent isothermal soaking treatments within evacuated quartz tubes for periods of 10 to 7000 hr at temperatures of 850, 750, 850, andd 950 deg F. In addition, the nickel barrier bond between Type 1100 aluminum cladding and cast U- 3.5% Mo fuel alloy was metallographically examined on four fuel cylinders fabricated according to Piqua procedure. One cylinder was inspected in the as fabricated'' conditions, and the three others after 1000, 2000, and 4000 hr of isothemnal soaking in Santowax OMP at 750 deg F in an autoclave under 100 psig of nitrogen. The following conclusions were obtained: 1) The penetration of aluminum into nickel followed a parabolic relationship with time. The penetration coefficient was graphically determined as a function of temperature. 2) The nickel penetration data generated by the diffusion couple technique were slightly higher thand those derived from the cylinder bond study. The maximum discrepancy was 20%. This disagreement was attributed to the geometry of the tubular specimens and to the interface displacements which occurred during the annealing process due to differential thermal expandsion between fuel and cladding, both at the OD and ID. 3) A low-aluminum phase AlN/sub 3/ or AlNi/sub 3/ nucleated at the Al/sub 3/Ni/Al/sub 3/Ni/sub 2/ interf ace when the supply of additional free Al into the system was restricted due to void formation or separation between intermetallics and Al. The growth of the low-aluminum phase progressed at the expense of the Al/sub 3/Ni until all this phase was consumed, then consumption of the Al/sub 3/Ni/sub 2/ phase began. 4) The interdiffusion rate of uranium and nickel also followed the parabolic relationship with time. The diffusion coefficient as a function of temperature was plotted. (auth