The Influence of Ternary Alloying Additions on the Galvanic Behavior of Aluminum-Tin Alloys

1969 ◽  
Vol 116 (3) ◽  
pp. 319 ◽  
Author(s):  
D. S. Keir ◽  
M. J. Pryor ◽  
P. R. Sperry
1999 ◽  
Vol 589 ◽  
Author(s):  
T.M. Miller ◽  
L. Wang ◽  
W.H. Hofmeister ◽  
J.E. Wittig ◽  
I.M. Anderson

AbstractAtom location by channeling enhanced microanalysis (ALCHEMI) has been used to characterize the site distributions of Nb and Cr alloying additions in the L10-ordered γ phase of ternary titanium aluminides. Two alloys, Ti50Al48Cr2 and Ti50A148Nb2, were processed by furnace cooling from 1300°C (within the α-γ two phase field) as well as by rapid solidification using twin-anvil splat quenching of electromagnetically levitated and undercooled samples. ALCHEMI studies of furnace cooled samples yield results generally consistent with those in the published literature. Nb alloying additions are found to partition exclusively to the ‘Ti’ sublattice, while Cr alloying additions exhibit an ‘Al‘ sublattice preference. However, a higher degree of disorder can be achieved with rapid solidification and high solid state cooling rates (105-106 K/s). Significant distribution of the ternary elements between the ‘Ti’ and ‘Al‘ sublattices has been measured in the splat quenched samples, with up to 12% of the Nb atoms occupying the ‘Al‘ sublattice and the fraction of Cr atoms on the ‘Ti’ sublattice doubling to ∼30%. Rapid solidification of TiAl produces an equiaxed hexagonal α phase solidification structure that transforms in a massive fashion to the tetragonal γ phase. Although the amount of massively transformed γ is dependent upon the solid state cooling rate, ternary alloying additions can more strongly influence the transformation kinetics. The Nb-modified alloy exhibits significant amounts of the massively tranformed γ, similar to the Ti52Al48 binary alloy, whereas little massively transformed γ is observed in the Cr-modified alloy. These results can be correlated with the relative atomic size, lattice distortion, and sublattice site occupancy of Nb and Cr in the L10 unit cell.


2011 ◽  
Vol 109 (7) ◽  
pp. 07B739 ◽  
Author(s):  
B. Wang ◽  
K. Barmak ◽  
T. J. Klemmer

1956 ◽  
Author(s):  
J.E. Reynolds ◽  
W.E. Berry ◽  
H.R. Ogden ◽  
R.S. Peoples ◽  
R.I. Jaffee

2006 ◽  
Vol 425 (1-2) ◽  
pp. 239-244 ◽  
Author(s):  
Guillermo Bozzolo ◽  
Hugo O. Mosca ◽  
Ronald D. Noebe

2007 ◽  
Vol 266 ◽  
pp. 191-198 ◽  
Author(s):  
N. Garimella ◽  
M.P. Brady ◽  
Yong Ho Sohn

Interdiffusion at 700°C for Ni-22at.%Cr (fcc γ phase) alloys with small additions of Al, Si, Ge, or Pd was examined using solid-to-solid diffusion couples. Rods of Ni-22at.%Cr, Ni- 21at.%Cr-6.2at.%Al, Ni-22at.%Cr-4.0at.%Si, Ni-22at.%Cr-1.6at.%Ge and Ni-22at.%Cr-1.6at.%Pd alloys were cast using arc-melt and homogenized at 900°C for 168 hours. The diffusion couples were assembled with alloy disks in Invar steel jig, encapsulated in Argon after several hydrogen flushes, and annealed at 700°C for 720 hours. Experimental concentration profiles were determined from polished cross-sections by using electron probe microanalysis with pure standards of Ni, Cr, Al, Si, Ge and Pd. Interdiffusion fluxes of individual components were calculated directly from the experimental concentration profiles, and the moments of interdiffusion fluxes were examined to determine average ternary interdiffusion coefficients. Effects of ternary alloying additions on the interdiffusional behavior of Ni-Cr-X alloys at 700°C are presented in the light of the diffusional interactions and the formation of protective Cr2O3 scale.


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