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 Pd₇₉Cu_6−xAu_xSi₁₀P₅ (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 (Pd₇₉Cu₄Au₂Si₁₀P₅) 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 (Pd₇₉Cu₄Au₂Si₁₀P₅) are 87 GPa, 1525 MPa and 1660 MPa, respectively, with a compressive plastic strain over 13%.