Table 1.

Lattice parameters of $ϵ$-Al₃Nb, $\sigma$-AlNb₂, and the ordered $\delta$-Al_0.19Nb_0.81 together with the corresponding elastic constants ($C_{ij}$ in GPa), the polycrystalline bulk (B in GPa), shear (G in GPa) and Youngs’s moduli (E in GPa). The $B/G$ and the Poisson’s ratio ($\nu$) represent ductility estimates, while the $E_{100}$/$E_{111}$ ratio between the Young’s moduli in the (100) and (111) direction relates to elastic isotropy.

	a	c	C 11	C 12	C 13	C 33	C 44	B	G	E	B/G	ν	E100/E111
ϵ-Al3Nb	3.851	8.644	248	96	46	267	99	132	102	242	1.23	0.18	0.82
σ-AlNb2	5.188	9.978	278	98	100	284	74	159	81	208	1.96	0.28	1.16
δ-Al0.19Nb0.81	5.215		268	114			54	165	62	166	2.62	0.33	1.36