New orthorhombic approximants of the Al₇₀Co₁₅Ni₁₀Tb₅ decagonal quasicrystal

Abstract

Three new orthorhombic approximants, C₁, C₂ and C₃, have been found in the Al₇₀Co₁₅Ni₁₀Tb₅ decagonal quasicrystal, which was prepared by a method of quenching from the melt under a high static pressure. The lattice parameters of these orthorhombic phases are as follows: C₁, a = 2.28nm, b= 1.60nm and c = 5.46nm (B type); C₂ a = 6.1 nm, b = 0.4 nm and c = 8.4 nm (P type); C₃, a = 6.1 nm, b = 0.4 nm and c = 8.4nm (Btype). The strong diffraction spots in the electron diffraction patterns of these phases show the same intensity modulation as those of the decagonal quasicrystal, implying a close relationship between them.