The strengthening role of micro-sized phases and nano-precipitates in Al-Mg2Si-Cu(-Ni) alloys at 25 °C and 350 °C

The strengthening of micro-sized phases and nano-precipitates to the Al-Mg2Si-Cu(-Ni) alloys was studied at 25 & DEG;C and 350 & DEG;C. In the Al-15%Mg2Si-5%Cu alloy, lots of nanoprecipitates (0'', 0', a and Q' precursor) are formed with the dissolution of Cu-rich phases after heat treatment. The high number density of nano-precipitates contributes to the high strength of alloy (357 MPa) at 25 & DEG;C. For the Al-15%Mg2Si-5%Cu-1%Ni alloy, more microsized Cu/Ni-rich phases are retained and fewer nano-precipitates (0'', 0', a and S phase) are formed after heat treatment. The existence of high-temperature stable micro-sized Cu/Nirich phases produce an enhanced strengthening effect (109 MPa) to the alloy at 350 & DEG;C, compared to that of Al-15%Mg2Si-5%Cu alloy (82 MPa).& COPY; 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).