Plastic Zr-Al-Ni-Cu-Ag bulk glassy alloys containing quasicrystalline or β-Zr plus ω-Zr phases

Zr70-76 Al7-7.5Ni13-15Cu2Ag2-5 glassy alloys were prepared by melt-spinning with Zr contents up to 76 at.%, greatly exceeding the highest Zr content of 70 at.% previously reported for Zr-based glassy alloys exhibiting a calorimetric glass transition. The 70-72Zr and 74Zr alloys were also cast as bulk rods up to 1.5 mm in diameter with glass and [glass + beta-Zr +omega-Zr] phases, respectively, by ejection copper-mold casting. The crystallization temperature and Vickers hardness Hv for the glassy ribbons decrease with increasing Zr content from 70 to 76 at.%. The glassy rods show high yield strength ( sy) of 1225-1346 MPa, high fracture strength (sf) of 1497-1499 MPa, and large compressive plastic strain (ep) of 9.7-3.2% for the 70-72Zr alloys. Similarly, the 74Zr rod with [glass + beta-Zr +omega-Zr] phases shows sy of 1325 MPa, sigma(f) of 1472 MPa, ep of 2.4%. The 76Zr thick ribbon with [glass + beta-Zr +omega-Zr] phases shows, in tension, high sigma(y) of 890 MPa, sf of 988 MPa, and plastic elongation of 0.3%. The Zr-rich glassy ribbons crystallize, showing three exothermic peaks upon heating. The first-stage peak is due to the precipitation of icosahedral quasicrystal (IQ) for the 70-72Zr ribbons, and beta-Zr +omega-Zr for the 74-76Zr ribbons. These annealing-induced mixed-phase ribbons with Zr content above 72 at.% exhibit good bending plasticity, even though their H-V is about 41% higher than for the as-spun glassy ribbons. Similarly, the 70Zr bulk rod, with [glass + IQ] phases obtained by annealing, shows a distinct increase in sy and sf to 1485 and 1575 MPa, respectively, as well as ep of 0.6%. Thus, the plastic Zr-rich bulk rods with glass, [glass + IQ], and [glass + beta-Zr +omega-r] phase mixtures are encouraging for the future development of a new type of high-strength structural material. (C)22 The Authors. Published by Elsevier Ltd on behalf of Acta Materialia Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/

Automated summary

Zr70-76 Al7-7.5Ni13-15Cu2Ag2-5 glassy alloys were prepared by melt-spinning and copper-mold casting, showing excellent mechanical properties and plasticity. The 70-72Zr and 74Zr alloys were cast as bulk rods with glass and [glass + beta-Zr +omega-Zr] phases, while the 76Zr alloy was prepared as a thick ribbon. The Zr-rich glassy ribbons also exhibited good bending plasticity after annealing.