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

The glass-forming ability (GFA), thermal stability and mechanical properties of bulk glassy Pd79Cu6 xAuxSi10P5 (x 1⁄4 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 (Pd79Cu4Au2Si10P5) exhibits the broadest supercooled liquid region ( Tx 1⁄4 80K) and possesses the highest GFA among the alloys investigated. The critical diameter for glass formation of this alloy reaches 7mm 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 (Pd79Cu4Au2Si10P5) are 87GPa, 1525MPa and 1660MPa, respectively, with a compressive plastic strain over 13%.