Microstructure and mechanical properties of 2024 aluminum MA alloy with 3 mass%Fe and 5 mass%Ni combined addition

Air atomized 2024Al-3Fe-5Ni alloy powder was mechanically alloyed (MA) for 0∼154.8 ks in an argon atmosphere. Subsequently, hot compacted at 673 K, and then hot pressed to 2 mm thickness plates at temperatures of 673 K∼793 K and at initial strain rates of 5 × 10^-1∼10 s^-1. The effect of MA time on the microstructure and hardness of MA powder, hot compacted blocks and hot compressed plates has been investigated in the light of improvement of ambient and high temperature strength of the alloy plates. Vickers hardness of MA powders and compacted blocks increased with increasing MA time up to 57.6 ks. Thus, the hot compressed MA alloy was stronger than the non MA alloy at temperatures up to about 573 K. The results of DSC, XRD and TEM revealed that the primary and eutectic intermetallic phases such as Al₃FeNi compounds were finely dispersed and finally the transition elements in some parts of compounds were super-saturated in matrix by the high energy of MA. The super-saturated elements were precipitated as finely and thermally stable dispersed particles at the temperature higher than about 673 K. Improvements in the ambient and elevated temperature strength are mainly attributed to the presence of extremely fine grain structure and finely dispersed particles which were introduced during MA and consolidation process.