Design of a new Al-Cu alloy manipulated by in-situ nanocrystals with superior high temperature tensile properties and its constitutive equation

Al-Cu alloys inoculated by in-situ nano-sized particles crystallized from Ni-Nb-Ti amorphous alloys were prepared by casting method in this work. Different compositions of Ni-Nb-Ti amorphous alloys significantly enhanced heterogeneous nucleation for alpha-Al and promoted obvious grain refinement of the Al-Cu alloys. It was found that 0.05 wt% Ni-Nb-Ti amorphous alloys addition caused a significant and efficient refinement on alpha-Al (from 200 mu m to 39 mu m) and theta' phase (from 146.4 nm to 37.6 nm). The strength and ductility of the inoculated alloy were improved significantly at high temperature. The tensile strength and fracture strain of the alloy inoculated by 0.05 wt% Ni-Nb-Ti amorphous alloy for 20 min at 533 K under the strain rates of 10(-1) s(-1) were increased by 32.63% and 90.35% respectively, compared to those of the uninoculated alloy. The nano-sized NiTi particles contributed to the grain refinement of alpha-Al, and grain refinement shortened the solute atomic diffusion distance and refined theta' phase during heat treatment, resulting in higher strength and plasticity at high temperature. The model developed for this newtype Al-Cu alloy is found to be efficient in predicting the stress at 453 K-533 K under the strain rates of 10(-4) s(-1) to 10(-1) s(-1). (C) 2019 The Authors. Published by Elsevier Ltd.