Development of High Temperature Aluminum Alloy by Optimum Control in Mechanical Solution Treatment-Nano Phase precipitation Process

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Mechanical alloying (MA) of air atomized (RS) 2024Al-3Fe-5 Ni and Al-3Fe-3 Ni-3Cr-0.7Zr (in mass%) alloy powder was performed with a vibrational ball mill for 0-154.8 ks in an argon atmosphere.1. The fine dispersions of intermetallic particles as Al_9FeNi phase and the quasicrystalline Al_<80>Cr_<13.5>Fe_<6.5> phase, respectively, were found to be the main factor for the strengthening of RS 2024Al-3Fe-5Ni and RS Al-3Fe-3Ni-3Cr-0.7Zr alloy at ambient and high temperature to 573K.2. The results of DSC,XRD and TEM revealed that, with MA time, the primary intermetallic compounds in atomized powder were dispersed finely and the transition elements in the many compounds were finally super-saturated in matrix by the high energy of MA.3. During hot-extrusion process at 673K,in the case of the Al-3Fe-3Ni-3Cr-0.7Zr alloy, the transition elements were precipitated finely as Al_3Fe, and Al_3Ni and Al_<13>Cr_2 phase particles on boundaries or interior of sub-grains formed extremely fine scale. The tensile strength at room temperature and at 573K were about 431.9MPa and 208.7MPa for extrusion specimen from atomized powder, and 675.7MPa and 281MPa for extrusion specimen from 154.8ks-MA powder, respectively. However the ductility was poor in MA materials.4. Improvements in the ambient and elevated temperature strength with MA are mainly attributed to the presence of extremely fine grain structure and finely dispersed particles which were introduced during MA and consolidation process.