X-ray diffraction study of the effect of boron on lattice properties of Ni₇₆Al₂₄

Abstract

A small addition of boron is suggested to increase the ductility of the polycrystalline Ni3Al when the Al content is less than 25 at.%. Both metallographic and x-ray investigation have shown the alloys of Ni3Al (24 at.% Al) containing 0.20, 0.42, 0.79, 0.98, and 1.22 at.% B to be of single phase and that of 1.76 at.% B to be of two phase. With the addition of boron, the lattice parameter of the Ni3Al phase is found to increase. Microhardness measurements indicate that initially the hardness decreases for the alloy of 0.20 at.% B, while for the rest of the single phase alloys the hardness is found to increase with further addition of boron. The addition of boron increases the deformation stacking fault probability value except for the alloy with 0.20 at.% B.

Modeling of lattice parameter in the Ni-Al system

“…Fig. 9-Room-temperature lattice parameter of the ␥Ј phase (ϩ, [32] ✚, [33] , [36] ٗ, [37] ϫ, [38] ✖, [39] , [40] , [41] G, [42] L, [43] ᭝, [44] M, [45] ᭞, [46] ᭛, [47] ᭜, [48] , [49] ᮆ, [50] ଝ, [51] I, [76] ᭺, [77] and [78] ). The solid line represents the results of the model calculation (S N ϭ 7.4 ϫ 10 Ϫ3 Å).…”

“…The room-temperature lattice parameters of the ␥Ј phase were determined by many investigators [32,33,[36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] on samples quenched mostly from 1173 to 1473 K. The temperature effect on the ␥Ј phase was studied by Arbazov and Zelenkov in the temperature range of 293 to 974 K [23] and by Taylor and Floyd for 74 to 1273 K [36] using the dilatometry technique, and their results on the relative thermal expansion agree with each other. Using high-temperature X-ray diffractometry, Kamara et al, [32] Rao et al, [52] and Stoeckinger and Neumann [45] investigated the temperature dependencies of the ␥Ј lattice parameter.…”