CALPHAD-guided alloy design of Cu–Pb–(X) immiscible alloy with rodlike secondary phases

Abstract

Novel Cu–24Pb–xAl alloys with dispersed and rodlike Pb-rich secondary phases (PSPs) were designed and prepared with the guidance of CALPHAD. Through primary binary-phase diagram analysis and thermodynamic calculation, Al was proven to be a suitable alloying element in Cu–Pb system to promote the formation of dispersed and rodlike PSPs during solidification by introducing a (L₁+L₂+α-Cu) phase region in Cu–Pb–xAl systems. The Cu–24Pb–xAl (wt-%, x = 0, 2, 4) alloys were then prepared in order to verify the reliability of the alloy design strategy. Cu–24Pb–2Al alloy with rodlike PSPs was successfully designed and prepared. A novel strategy to design Cu–Pb–(X) immiscible alloy with optimised microstructure is thus proposed in this work which can help establish a design criterion for other immiscible alloys.