Leaching of Al-Based Polygrain Quasicrystalline and Related Crystalline Surfaces

Abstract

In the present investigation, we have studied leaching on polygrain Al-based quasicrystalline (i-Al63Cu25Fe12) as well as crystalline (B2 phase; Al55Cu30Fe15) alloy surfaces using a 10 mole NaOH solution. The surface was leached at varying times from 30 min to 8 h and subsequently characterized by X-ray diraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray analysis. Leaching of the samples for 30 min generated a homogeneous layer. However further leaching for 18 h yielded nano-size particles on the surface. Spherical microstructure has been observed on the AlCuFe crystalline surface whereas on the quasicrystalline surface a petal-like microstructure appeared. The implications of the evolution of dierent microstructures in the context of structure, stability and activity are discussed. The results are compared with the microstructure of leached polygrained samples containing a mixture of dierent surface orientations.