Microstructure and mechanical properties of Ag and Ge multi-micro alloyed Al-(3.2) Cu-(2) Li-(0.6) Mg alloys

This work represent an attempt to investigate the possible improvement to replace (Cu) by (Li) in (Al-Cu) alloys used in aerospace industries. It is well established that (Al-Li) alloys are attractive for military and aerospace application because their properties are superior to those of congenital (Al) alloys. (Li) reduced the weight of the plane; hence, more speed can be attained. Several other improvements are also intruded. Alloys were prepared during this work by casting. they include (Al-Li-Cu-Mg-Zr), (Al-Li-Cu-Mg-Zr-Ag), and (Al-Li-Cu-Mg-Zr-Ag-Ge) alloys. Result showed that addition 0.35%Ag to Al-Li-Cu-Mg-Zr alloy improve strength from (42MPa) to (127MPa) when aging at 175°C. and improve hardness from (156.64 Hv) to (173.74Hv) At the same temperature. But the deterioration when addition 0.2 Ge to Al-Li-Cu-Mg-Zr alloy weakness strength from (127MPa) to (26MPa) at the same time improved hardness from (156.64Hv) to (171.76Hv) at the same temperature. Optical microscopy (OM), X-ray diffraction (XRD) were done to study the structure and the surface features and chemical composition of the alloys. Many phases shown which have an influence on the mechanical and chemical properties, such as (Al 3 Li), (Al 3 Zr), (Al 2 MgLi), omega (Ω) precipitates, (Ag 2 CuLi), (Ge 4 Zr 5 ).Pin-on-disc testing technique was commonly used for investigating sliding wear. B significant increase in wear resistance of the alloy. The weight loss was only 60% of the other alloys.