Insight into γ-Ni/γ'-Ni_3Al interfacial energy affected by alloying elements

摘要

Interfacial energy (sigma(gamma/gamma ')) of the gamma-Ni/gamma '-Ni3Al interface is critical to understand and design Ni-based superalloys. In the present work, a first-principles methodology with constrained relaxations has been used to study the effect of dilute alloying element (X) on sigma(gamma/gamma ') of the (100) coherent interface, where the sixteen X's include Al, Co, Cr, Fe, Hf, Mo, Nb, Pd, Pt, Re, Ru, Ta, Ti, W, Y, and Zr. sigma(gamma/gamma) = 19mJ/m(2) has been predicted for the unalloyed gamma/gamma ' interface, agreeing well with the previous estimations. It is found that the sigma(gamma/gamma) value is the lowest when alloying element is in gamma-Ni, while the addition to gamma '-Ni3Al increases sigma(gamma/gamma) due mainly to the in-plane lattice expansion. Specifically, our calculations show that alloying elements Mo, W, and Re have the largest effect on the sigma(gamma/gamma) value by decreasing it to 4-5 mJ/m(2) when partitioned to gamma-Ni; Ru and Pt are shown to increase greatly the sigma(gamma/gamma) value up to 2528 mJ/m(2) when partitioned to gamma-Ni; all ternary additions substituting for Ni in gamma '-Ni3Al increase sigma(gamma/gamma) except for Pt; and for Ti and Ta, which segregate strongly to gamma '-Ni3Al and substitute for Al, the sigma(gamma/gamma) values increase to 32 and 35 mJ/m2, respectively. (C) 2017 Elsevier Ltd. All rights reserved.