Mechanical properties of Al-Li-Cu icosahedral quasicrystals

Poly-quasicrystalline samples of an icosahedral Al-Li-Cu alloy have been deformed in compression at a constant engineering strain rate, at temperatures ranging from 300 to 773 K (Tm ≅ 896 K). The samples are very brittle below about 500 K but rather ductile above this temperature, with an upper yield stress decreasing linearly with increasing temperature, from 225 MPa at about 473 K to 22 MPa at 773 K. Load relaxation behavior and activation parameter values suggest that, in this material, plastic deformation at high-temperature is controlled by a thermally activated process that involves atomic diffusion.