Effects of Cr and V impurities on cohesion properties of Pd/TiAl interfaces

Abstract

First principles calculations reveal that for Pd/TiAl interfaces the substitution of interface Ti atoms with Cr or V atoms is energetically favorable with negative heat of formation, and could bring about a very small increase of interface bond strength, while the interstitial Cr and V atoms should be unfeasible with highly positive heat of formation and would increase the bond lengths of interface Pd–Al and Pd–Ti bonds. Calculations also demonstrate that both Cr and V would induce an increase of interface energy, suggesting that the impurity atoms of Cr or V should be reduced to a minimum level, in order to get a thermally stable Pd/TiAl interface with a longer lifetime. In addition, it is found that the substitution of V at the Pd/TiAl interfaces should be much easier than that of Cr, which is in good agreement with similar experimental observations in the literature.