Site occupation determination of Pd in Ni 3Al by ALCHEMI

Abstract

Atom location, by channeling enhanced microanalysis (ALCHEMI), was performed to examine the substitution behavior of Pd atoms added to a Ni 3Al intermetallic compound. From the quantitative analysis, it can be concluded that Pd has a strong tendency to locate in the Ni site of the compositions Ni 75Al 23Pd 2, Ni 74Al 24Pd 2, and Ni 73Al 25Pd 2, which means that the anti-structure defects are formed in the compositions of Ni 75− x Al 25− y Pd x+ y ( x ≦ y, y ≠ 0). In addition, the above results are thermodynamically discussed by considering the formation of the anti-structure defects introduced by Pd addition. It is investigated as to whether the substitution behavior of ternary alloying elements, which are known to substitute for the Ni site in the composition of Ni 75− x Al 25C x , depend on the composition of the host elements when they are added to the composition of Ni 75Al 25− x C x .