Synthesis of nano-quasicrystalline Al70Ni15Co15 decagonal phase through high energy ball milling

In the present investigation we have synthesized the nano-decagonal phase by mechanical milling of a pre-alloyed Al70Co15Ni15 decagonal phase. The milling was performed at a speed of 400 rpm for 5, 10, 20 and 40 h under a hexane medium with a ball: charge ratio 20:1. The nano-phase constituents were confirmed by X-ray diffraction and transmission electron microscopy techniques. The stability of the nano-D phase in the milled powder was also investigated under various annealing treatments. After 10 h milling, the evolution of the nano-decagonal phase was observed. This nano-phase was found to be stable up to 40 It of milling. The milled powder after 40 h of milling confirms the existence of a nano-decagonal phase. The particle size of the milled powder was similar to10-15 nm. An isothermal heat treatment of the milled sample at 500 degreesC for 10 h still shows the existence of the nano-decagonal phase, although a coarsening of the nano-domain has been observed. (C) 2004 Elsevier B.V. All rights reserved.