Effect of yttrium addition on the formation and mechanical properties of Ti–Zr–Ni–Cu bulk quasicrystalline alloys

The effect of yttrium (Y) on the structure and mechanical properties of the as-cast (Ti48Zr36Ni14Cu2)1−xYx (x = 0, 0.01 and 0.02) bulk quasicrystalline alloys was investigated. These alloys were mainly composed of icosahedral quasicrystalline phase (i-phase) accompanied by minor hexagonal C14 Laves phase and solid-solution β-(Ti/Zr) phase. The characterization on their mechanical properties had been carried out by means of microhardness indentation and compression tests at room temperature. The microhardness test showed that the toughness of them was much better than many other i-phase alloys because no obvious crack was detected even at the load of 4.9 N. The compressive fracture strengths first increased and then decreased with increasing x, and the highest strength was 1350 MPa when x = 0.01, it was 210 MPa higher than the without Y alloy. These results reveal that an appropriate amount of Y addition would enhance the mechanical properties of the bulk i-phase alloy.

► The yttrium (Y) is first used as an effective alloying element to improve the mechanical properties of Ti–Zr–Ni–Cu quasicrystalline as-cast alloys. ► The maximum compressive fracture strength of 1351 MPa and good elastic deformation of 6.12% is exhibited in the (Ti48Zr36Ni14Cu2)0.99Y0.01 alloy. ► These alloys show better toughness because no obvious crack is detected even at the load of 4.9 N.