Interdiffusion in L12-Ni3Al Alloyed with Re

Ternary interdiffusion in L12-Ni3Al with ternary alloying addition of Re was investigated at 1473 K using solid-to-solid diffusion couples. Interdiffusion flux of Ni, Al, and Re were directly calculated from experimental concentration profiles and integrated for the determination of average ternary interdiffusion coefficients. The magnitude of main interdiffusion coefficients \( \bar{\tilde{D}}_{\text{NiNi}}^{\text{Al}} \) and \( \bar{\tilde{D}}_{\text{AlAl}}^{\text{Ni}} \) was determined to be much larger than that of the main interdiffusion coefficient \( \bar{\tilde{D}}_{\text{ReRe}}^{\text{Al (or Ni)}}. \) A moderate tendency for Re to substitute for Al sites was reflected by its influence on interdiffusion of Al, quantified by large and positive \( \bar{\tilde{D}}_{\text{AlRe}}^{\text{Ni}} \) coefficients. Similar trends were observed from ternary interdiffusion coefficients determined by Boltzmann-Matano analysis. Profiles of concentrations and interdiffusion fluxes were also examined to estimate binary interdiffusion coefficients in Ni3Al, and tracer diffusion coefficients of Re (5.4 × 10−16 ± 2.3 × 10−16 m2/s) in Ni3Al.