2021 Volume 71 Issue 7 Pages 275-282
In the present study, we investigated the effects of Cu or Ni additions on the precipitation of intermetallic phases in the heat-resistant aluminum alloy with a ternary composition of Al-5Mg-3.5Zn (mol%). The quaternary alloys with 1 mol%Cu or 1 mol%Ni content were solution-treated at 480 °C and subsequently aged at 300 °C for different periods. Both Cu and Ni additions have a slight effect on the age-hardening of these alloys at 300 °C. The added Cu element partitioned into not only T-Al6Mg11Zn11 phase but η-Zn2Mg phase precipitated in the α-Al matrix. The observed Cu enrichment in the precipitates of T phase indicated high stability of T phase in the Al-Mg-Zn-Cu quaternary system, which was different from the results of thermodynamic calculations using the existing database. The added Ni element enhanced the formation of fine Al3Ni phase located at grain boundaries and slightly influenced the precipitation of T phase in grain interior. These results provided new insights to design novel heat-resistant Al alloys using the Al-Mg-Zn-Cu-Ni system.
