Diffusion of63Ni and114mIn in the γ′-phase Ni3Al

Abstract

The diffusion of 63Ni and 114mIn in the intermetallic L12 phase Ni3Al is measured in the temperature range from 900 to 1200 °C and for compositions between 73.5 and 77 at% Ni in steps of 0.5 at%. The In isotope serves as a substitute for 26Al. The usual serial sectioning method is applied using a precision parallel grinder. There is only a weak concentration dependence of the diffusion coefficient at temperatures > 950 °C but it gets stronger with decreasing temperature. There is a minimum of the diffusion coefficient at 76 and not at 75 at% Ni as may be expected. The diffusion of 63Ni in Ni3Al and in pure Ni is comparable. The same is true for the diffusion of 114mIn in Ni3Al. Very likely the diffusion of 63Ni is by a normal vacancy mechanism and the diffusion of 114mIn by In antisite atoms in the Ni sublattice. The D 0*‐values are for In (and probably for Al as well) considerably higher than for Ni. This could be due to a higher entropy term. As a consequence of the considerably larger D 0*‐values of In an intersection of the two linear Arrhenius plots for Ni and Al is observed at about 950 °C for all concentrations except Ni76Al24. This fits well to interdiffusion investigations where at higher temperatures Al is found to be the faster component, and Ni at lower temperatures.

Interdiffusion in L12-Ni3Al Alloyed with Re

“…4. These values appear consistent with the available binary interdiffusion data [3][4][5][6][7][8][9][10] for Ni 3 Al.…”

“…[1] Multicomponent diffusion plays an important role in processing and degradation of these alloys that must possess exceptional high-temperature strength, microstructural stability, and oxidation resistance. Multicomponent diffusion mobility database [2] for c phase, together with the alloying studies [3][4][5][6][7][8][9][10] to modify coherent precipitate (c¢) have yielded excellent design criteria to develop advanced superalloys. Recent development of refractory-based superalloys with L1 2 precipitates, and refractory-modified aluminide coatings [11][12][13][14][15][16] warrant a better understanding of interdiffusion in Ni 3 Al with alloying additions.…”

Probing diffusional jumps in ordered compounds by anelastic relaxation spectroscopy

“…In measurements in torsional vibration using single crystal specimens, the relaxation magnitude is the largest in specimens whose torsional axis is oriented to h111i, while it is very small in those oriented to h001i. The values of the activation parameters suggest a Zenertype mechanism, namely stress-induced reorientation of substitutional-defect complexes, as the activation energy of 3 eV is close to the activation energy of the diffusion of Ni in Ni 3 Al [8,9].…”

Non-integer temporal exponents in trans-interface diffusion-controlled coarsening

“…The calculations of D Al are done for four compositions, using the data of Hoshino et al [67] (X Al = 0.2384) and the data of Shi et al [69] Fig. 4, and, finally, D Al is calculated using Eq.…”

“…Absent a concentration-dependent interface width, this can be explained by the TIDC theory only if some other factor is incorporated into the theory to account for non-integer values of n, in particular a factor that depends relatively strongly on alloy concentration over the small concentration changes attendant to particle coarsening. The most obvious candidate is the intrinsic diffusion coefficient of Al in Ni 3 Al, which is already quite well known to be [65], filled triangle Bronfin et al [66], filled square Hoshino et al [67], filled downward triangle Frank et al [68] and filled circle Shi et al [69]. concentration dependent (see Campbell [46] for a compendium of results).…”