Effect of Minor Au Addition on Glass-Forming Ability and Mechanical Properties of Pd–Cu–Au–Si–P Alloys

Abstract

The glass-forming ability (GFA), thermal stability and mechanical properties of bulk glassy Pd 79 Cu 6-x Au x Si 10 P 5 (x = 0-6 at%) alloys were studied. The results revealed that the minor substitution of Au for Cu strongly affects the thermal stability and GFA of Pd-Cu-Au-Si-P alloys. The alloy in which 2 at% Au was added to substitute Cu (Pd 79 Cu 4 Au 2 Si 10 P 5 ) exhibits the broadest supercooled liquid region (ΔT x = 80 K) and possesses the highest GFA among the alloys investigated. The critical diameter for glass formation of this alloy reaches ∼7 mm by copper mold casting. The GFA is dramatically reduced when the Au content is more than 5 at%, beyond which no bulk glasses could be formed. The Young's modulus, yield strength and maximum compressive strength of the best glass former (Pd 79 Cu 4 Au 2 Si 10 P 5 ) are 87 GPa, 1525 MPa and 1660 MPa, respectively, with a compressive plastic strain over 13%.