High-strength materials produced by precipitation of icosahedral quasicrystals in bulk Zr–Ti–Cu–Ni–Al amorphous alloys

Abstract

${\mathrm{Zr}}_{\text{62−x}}{\mathrm{Ti}}_x{\mathrm{Cu}}_{\mathrm{20}}{\mathrm{Ni}}_{\mathrm{8}}{\mathrm{Al}}_{\mathrm{10}}\text{\hspace{0.05em}(3⩽x⩽5)}$ amorphous alloys crystallize via precipitation of icosahedral quasicrystals in the primary crystallization step, leading to nano-sized quasicrystals embedded in an amorphous matrix. Ti is the decisive component favoring the precipitation of quasicrystals. The mechanical properties of the crystallized alloys with different amounts of quasicrystalline phase were measured by compression and bending tests. If the volume fraction of quasicrystalline precipitates is below about 50%, the strength increases with an increasing amount of quasicrystalline precipitates, but the ductility does not decrease significantly in comparison with the amorphous counterpart. The fracture stress reaches 1835 MPa for 50 vol % of quasicrystals. Quasicrystalline precipitates of more than 60 vol % lead to reduction of ductility and strength. This shows a way of producing bulk quasicrystalline materials of high strength by crystallization of bulk amorphous alloys.